RFC 2669
DOCSIS Cable Device MIB Cable Device Management Information Base for DOCSIS compliant Cable Modems and Cable Modem Termination Systems
DOCSIS Cable Device MIB 🎀
Cable Device Management Information Base for DOCSIS compliant Cable Modems and Cable Modem Termination Systems
Okay bestie, the title block tea ☕ This is RFC 2669, published by the Network Working Group in August 1999. M. St. Johns is the editor (that "Ed." just means editor 💅), and the whole thing came out of @Home Network. It's a Proposed Standard, so it's on the standards track 🦋 The header doesn't list anything it obsoletes or updates, so there's no drama there.
Status of this Memo ✨
This document is an Internet standards track protocol for the Internet community, and it's literally asking for discussion and suggestions for improvements 🫶 To see where this protocol stands in the standardization state and status, check the current edition of the "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited, so share away 💜
Copyright Notice 🌈
Copyright (C) The Internet Society (1999). All Rights Reserved.
Abstract 🦋
This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. Basically, it's a basic set of managed objects for SNMP-based management of DOCSIS 1.0 compliant Cable Modems and Cable Modem Termination Systems 🍓
This memo specifies a MIB module that is compliant to the SNMP SMIv2 [5][6][7]. The set of objects is consistent with the SNMP framework and existing SNMP standards.
This memo is a product of the IPCDN working group within the Internet Engineering Task Force. Comments are solicited, so send them to the working group's mailing list at ipcdn@terayon.com and/or the author 📬
Table of Contents 📑
1 The SNMP Management Framework ................................... 2
2 Glossary ........................................................ 3
2.1 CATV .......................................................... 3
2.2 CM ............................................................ 3
2.3 CMTS .......................................................... 4
2.4 DOCSIS ........................................................ 4
2.5 Downstream .................................................... 4
2.6 Head-end ...................................................... 4
2.7 MAC Packet .................................................... 4
2.8 MCNS .......................................................... 4
2.9 RF ............................................................ 4
2.10 Upstream ..................................................... 4
3 Overview ........................................................ 4
3.1 Structure of the MIB .......................................... 5
3.2 Management requirements ....................................... 6
3.2.1 Handling of Software upgrades ............................... 6
3.2.2 Events and Traps ............................................ 6
3.2.3 Trap Throttling ............................................. 8
3.2.3.1 Trap rate throttling ...................................... 8
3.2.3.2 Limiting the trap rate .................................... 8
3.3 Protocol Filters .............................................. 9
3.3.1 Inbound LLC Filters - docsDevFilterLLCTable ................ 10
3.3.2 Special Filters ............................................ 10
3.3.2.1 IP Spoofing Filters - docsDevCpeTable .................... 10
3.3.2.2 SNMP Access Filters - docsDevNmAccessTable ............... 10
3.3.3 IP Filtering - docsDevIpFilterTable ........................ 11
3.3.4 Outbound LLC Filters ....................................... 13
4 Definitions .................................................... 13
5 Acknowledgments ................................................ 51
6 References ..................................................... 51
7 Security Considerations ........................................ 52
8 Intellectual Property .......................................... 54
9 Author's Address ............................................... 54
10 Full Copyright Statement ...................................... 551. The SNMP Management Framework 🧚
Okay so the SNMP Management Framework is currently made up of five major components, and it's giving organized 💅
- An overall architecture, described in RFC 2571 [1].
- Mechanisms for describing and naming objects and events for the purpose of management. The first version of this Structure of Management Information (SMI) is called SMIv1 and is described in STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The second version, called SMIv2, is described in STD 58, RFC 2578 [5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7].
- Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and is described in STD 15, RFC 1157 [8]. A second version, SNMPv2c, which is not an Internet standards track protocol, is described in RFC 1901 [9] and RFC 1906 [10]. The third version of the message protocol is called SNMPv3 and is described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12].
- Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [8]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [13].
- A set of fundamental applications described in RFC 2573 [14] and the view-based access control mechanism described in RFC 2575 [15].
Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the mechanisms defined in the SMI.
This memo specifies a MIB module that is compliant to the SMIv2. A MIB conforming to the SMIv1 can be produced through the appropriate translations. The resulting translated MIB must be semantically equivalent, except where objects or events are omitted because no translation is possible (use of Counter64). Some machine readable information in SMIv2 will be converted into textual descriptions in SMIv1 during the translation process. However, this loss of machine readable information is not considered to change the semantics of the MIB.
2. Glossary 📖
The terms in this document are derived either from normal cable system usage, or from the documents associated with the Data Over Cable Service Interface Specification process.
2.1. CATV ✨
Originally "Community Antenna Television", now used to refer to any cable or hybrid fiber and cable system used to deliver video signals to a community.
2.2. CM 📺
Cable Modem.
A CM acts as a "slave" station in a DOCSIS compliant cable data system.
2.3. CMTS 🔥
Cable Modem Termination System.
A generic term covering a cable bridge or cable router in a head-end. A CMTS acts as the master station in a DOCSIS compliant cable data system. It is the only station that transmits downstream, and it controls the scheduling of upstream transmissions by its associated CMs. Main character energy, no cap 👑
2.4. DOCSIS 🌸
"Data Over Cable Interface Specification". A term referring to the ITU-T J.112 Annex B standard for cable modem systems [20].
2.5. Downstream ⬇️
The direction from the head-end towards the subscriber.
2.6. Head-end 🏠
The origination point in most cable systems of the subscriber video signals. Generally also the location of the CMTS equipment.
2.7. MAC Packet 📦
A DOCSIS PDU.
2.8. MCNS 🫧
"Multimedia Cable Network System". Generally replaced in usage by DOCSIS.
2.9. RF 📡
Radio Frequency.
2.10. Upstream ⬆️
The direction from the subscriber towards the head-end.
3. Overview 🦋
This MIB provides a set of objects required for the management of DOCSIS compliant Cable Modems (CM) and Cable Modem Termination Systems (CMTS). The specification is derived from the DOCSIS Radio Frequency Interface specification [16]. Please note that the DOCSIS 1.0 standard only requires Cable Modems to implement SNMPv1 and to process IPv4 customer traffic. Design choices in this MIB reflect those requirements. Future versions of the DOCSIS standard are expected to require support for SNMPv3 and IPv6 as well 🔮
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [19] 🎀
3.1. Structure of the MIB 🧩
This MIB is structured into seven groups:
- The
docsDevBasegroup extends the MIB-II 'system' group with objects needed for cable device system management. - The
docsDevNmAccessGroupprovides a minimum level of SNMP access security (see Section 3 of [18]). - The
docsDevSoftwaregroup provides information for network-downloadable software upgrades. See "Handling of Software Upgrades" below.. - The
docsDevServergroup provides information about the progress of the interaction between the CM or CMTS and various provisioning servers. - The
docsDevEventgroup provides control and logging for event reporting. - The
docsDevFiltergroup configures filters at link layer and IP layer for bridged data traffic. This group consists of a link-layer filter table,docsDevFilterLLCTable, which is used to manage the processing and forwarding of non-IP traffic; an IP packet classifier table,docsDevFilterIpTable, which is used to map classes of packets to specific policy actions; a policy table,docsDevFilterPolicyTable, which maps zero or more policy actions onto a specific packet classification, and one or more policy action tables.
At this time, this MIB specifies only one policy action table, docsDevFilterTosTable, which allows the manipulation of the type of services bits in an IP packet based on matching some criteria. The working group may add additional policy types and action tables in the future, for example to allow QOS to modem service identifier assignment based on destination.
- The
docsDevCpegroup provides control over which IP addresses may be used by customer premises equipment (e.g. PCs) serviced by a given cable modem. This provides anti-spoofing control at the point of origin for a large cable modem system. This group is separate fromdocsDevFilterprimarily as this group is only implemented on the Cable Modem (CM) and MUST NOT be implemented on the Cable Modem Termination System (CMTS). Triple-check that one, bestie, it's a hard no on the CMTS 🚫
3.2. Management requirements 💜
3.2.1. Handling of Software upgrades ✨
okay so the cable modem software upgrade process is written up in [16] 💾. from a network management station, the operator:
- sets
docsDevSwServerto the address of the TFTP server for software upgrades - sets
docsDevSwFilenameto the file pathname of the software upgrade image - sets
docsDevSwAdminStatustoupgrade-from-mgt
one reason the SNMP-initiated upgrade is so useful is that you can load a temporary software image (think special diagnostic software) that's different from what the device normally runs, and you don't have to change the provisioning database to do it 🧪🎀
note that software upgrades should not be accepted blindly by the cable device 🙅♀️ the cable device may refuse an upgrade if:
- The download is incomplete.
- The file contents are incomplete or damaged.
- The software is not intended for that hardware device (may include the case of a feature set that has not been purchased for this device).
3.2.2. Events and Traps 🚨
this MIB gives you control over reporting events through syslog, traps, and non-volatile logging 📒 if events are reported through traps, the specified conventions must be followed. other ways of reporting events are outside the scope of this document, so we're not going there 🙃
the definition and coding of events is vendor-specific, but the people who have to troubleshoot multi-vendor networks deserve better, so the circumstances and meaning of each event should be reported as human-readable text 🫶 vendors SHOULD provide time-of-day clocks in CMs so events get useful timestamps ⏰
for each vendor-specific event that's reportable via TRAP, the vendor must create an enterprise-specific trap definition. trap definitions MUST include the event reason encoded as DisplayString and should be defined as:
trapName NOTIFICATION-TYPE
OBJECTS {
ifIndex,
eventReason,
other useful objects
}
STATUS current
DESCRIPTION
"trap description"
::= Object Idnote that ifIndex is only included if the event or trap is interface related 💅
an example (fake) vendor defined trap might be:
xyzVendorModemDropout NOTIFICATION-TYPE
OBJECTS {
eventReason,
xyzModemHighWatermarkCount
}
STATUS current
DESCRIPTION
"Sent by a CMTS when a configurable number of modems
(xyzModemHysteresis) de-register or become unreachable during
the sampling period (5 minutes). Used to warn a management
station about a catastrophic cable plant outage."
::= { xyzTraps 23 }in this example, eventReason is a DisplayString providing a human readable error message, and xyzModemHighWatermarkCount is a Gauge32 which indicates the maximum number of modems during the epoch 📊
the last digit of the trap OID for enterprise-specific traps must match docsDevEvId 🔢 for SNMPv1-capable Network Management systems, this is necessary to correlate the event type to the trap type. many Network Management systems can only filter traps on an enterprise and single-last-digit basis, so this matters a lot 🥹
3.2.3. Trap Throttling 🛑
the CM and CMTS MUST provide support for trap message throttling, as described below. the network operator can use message rate throttling or trap limiting by manipulating the appropriate MIB variables 🎛️
3.2.3.1. Trap rate throttling
network operators can pick either of two rate control methods 💁♀️ in the first method, the device stops sending traps when the rate goes over the specified maximum message rate. it only starts sending again if a network management station reactivates it with a request.
in the second method, the device starts sending traps again once the rate drops below the specified maximum message rate 📉📈
the network operator sets the specified maximum message rate by setting the measurement interval (in seconds) and the maximum number of traps that can be sent within that interval. the operator can check the operational throttling state (to see whether traps are enabled or blocked by throttling) and can both query and set the administrative throttling state (to manage the rate control method) 🧠✨
3.2.3.2. Limiting the trap rate
sometimes network operators just want to cap how many traps a device sends over a set time period 🧢 the device stops sending traps once the number of traps goes over the specified threshold, and it only resumes after the measurement interval has passed ⏳
the network operator decides the maximum number of traps they're willing to handle and sets the measurement interval to a large number (in hundredths of a second). for this case, the administrative throttling state is set to stop at threshold, which is the maximum number of traps 💜
for more info, see "Techniques for Managing Asynchronously Generated Alerts" [17] 📚
3.3. Protocol Filters 🧚
the Cable Device MIB has objects for both LLC and IP protocol filters 🦋 the LLC protocol filter entries can be used to limit CM forwarding to a restricted set of network-layer protocols (such as IP, IPX, NetBIOS, and Appletalk) 🌐
the IP protocol filter entries can be used to restrict upstream or downstream traffic based on source and destination IP addresses, transport-layer protocols (such as TCP, UDP, and ICMP), and source and destination TCP/UDP port numbers 🎯
in general, a cable modem applies filters (or, more properly, classifiers) in an order that fits the layering model 🍰 specifically, the inbound MAC (or LLC) layer filters go first, then the "special" filters, then the IP layer inbound filters, then the IP layer outbound filters, then any final LLC outbound filters. since the cable modem doesn't generally do any IP processing (other than what the filters specify), the processing of the IP in filters and IP out filters can usually be combined into a single step 🫧
***************
* LLC Filters *
***************
| | |
v | v
************ | ***************
* IP Spoof * | * SNMP Access *
************ | ***************
| | |
v v v
****************
* IP Filter In *
****************
|
v
*****************
* IP Filter Out *
*****************
|
v
***********
* LLC Out *
***********3.3.1. Inbound LLC Filters - docsDevFilterLLCTable 🚧
the inbound LLC (or MAC or level-2) filters live in the docsDevFilterLLCTable and get applied to level-2 frames entering the cable modem, either from the RF MAC interface or from one of the CPE (ethernet or other) interfaces 📥 they're there to stop certain types of level-2 traffic that could be disruptive to the network 🙅 as currently specified, the filters can be set to either drop frames that match at least one filter, or to process a frame that matches at least filter. some example setups would be to only permit IP (and ARP) traffic, or to drop NETBUEI traffic 🫠
3.3.2. Special Filters ⭐
special filters get applied after the packet is accepted from the MAC layer by the IP module, but before any other processing happens 🙌 they only apply to a very specific class of traffic, so they're basically the VIP section 👑
3.3.2.1. IP Spoofing Filters - docsDevCpeTable 🕵️♀️
IP spoofing filters get applied to packets entering the modem from one of the CPE interfaces. their job is to stop a subscriber from stealing or misusing IP addresses that weren't assigned to them 🚫 if the filters are active (enabled), the source address of the IP packet must match at least one IP address in this table, or it gets discarded without further processing 🗑️
the table can be filled in automatically, where the first N different IP addresses seen from the CPE side of the cable modem are used to populate it 🤖 the spoofing filters are specified in the docsDevCpeTable, and the policy for automatically creating filters in that table is controlled by docsDevCpeEnroll and docsDevCpeMax as well as the network management agent 🎀
3.3.2.2. SNMP Access Filters - docsDevNmAccessTable 🔐
the SNMP access filters get applied to SNMP packets entering from any interface and destined for the cable modem. if the packets come in from a CPE interface, the SNMP filters are applied after the IP spoofing filters 🧱 these filters only apply to SNMPv1 or SNMPv2c traffic, and they aren't consulted for SNMPv3 traffic (and don't need to be implemented by a v3 only agent) 🫣 SNMPv3 access control is specified in the User Security Model MIB in [12] 💖
3.3.3. IP Filtering - docsDevIpFilterTable ✨
okay bestie, the IP Filtering table is a classifier table 🧚 Each row is a little template that incoming packets get compared against. The template includes source and destination addresses (plus their masks), the upper level protocol (like TCP or UDP), source and destination port ranges, and TOS plus TOS mask. Rows also carry interface and traffic direction match values, and those get considered in combination with everything else 🎀
So every column of a row must match the matching field in the packet, and the interface and direction items must match too, before the packet counts as a match. no cap, it's giving strict bouncer energy 💅
When the agent classifies a packet, it scans the table starting with the lowest numbered filter. If it finds a match, it applies the group of policies specified. But if the matched filter has the continue bit set, the agent keeps scanning and can match more filters and apply more policies 🦋 This is how one set of actions can cover the 24.0.16/255.255.255.0 group and a different set for telnet packets to and from 24.0.16.30. Those sets of actions don't have to be mutually exclusive, which is so iconic 👑
Once a packet is matched, one of three things happens depending on docsDevFilterIpControl in the row. The packet can be dropped, in which case no further processing is needed 💀 The packet can be accepted, and processing carries on. Or the packet can have a set of policy actions applied to it. If docsDevFilterIpContinue is set to true, scanning of the table keeps going, and more matches might happen 🌈
When a packet matches and docsDevFilterIpControl in the matched filter is set to 'policy', the value of docsDevFilterIpPolicyId is used as a selector into the docsDevFilterPolicyTable. This first level of indirection can lead to zero or more actions being taken based on the match 🍓 The docsDevFilterPolicyTable is scanned in row order, and every row where docsDevFilterPolicyId equals docsDevFilterIpPolicyId has the action specified by docsDevFilterPolicyValue 'executed'.
For example, a value pointing at an entry in the docsDevFilterTosTable could rewrite the TOS bits in the matched IP packet. Another option is assigning an output packet to a specific output upstream queue. And an even more complex action could rewrite the TOS value, assign the packet to an upstream service ID, and drop it into a particular IPSEC tunnel. main character energy 🔥
Example:
docsDevFilterIpTable
# Index, SrcIP/Mask, DstIP/Mask,ULP, SrcPts,DstPts,Tos/Mask,
# Int/Dir, Pgroup, [continue]
# drop any netbios traffic
10, 0/0, 0/0, TCP, any, 137-139, 0/0, any/any, drop
# traffic to the proxy gets better service - other matches possible
20, 0/0, proxy/32, TCP, any,any, 0/0, cpe/in, 10, continue
# Traffic from CPE 1 gets 'Gold' service, other matches possible
30, cpe1/32, 0/0, any, any,any, 0/0, cpe/in, 20, continue
# Traffic from CPE2 to work goes, other traffic dropped
40, cpe2/32, workIPs/24, any, 0/0, cpe/in, accept
45, cpe2/32, 0/0, any, any,ayn, 0/0, cpe/in, drop
# Traffic with TOS=4 gets queued on the "silver" queue.
50, 0/0, 0/0, any, any,any, 4/255, cpe/in, 30
# Inbound "server" traffic to low numbered ports gets dropped.
60, 0/0, 0/0, TCP, any,1-1023, 0/0, cpe/out, drop
65, 0/0, 0/0, UDP, any,1-1023, 0/0, cpe/out, drop
docsDevFilterIpPolicyTable
#
# index, policy group, policy
10, 10, queueEntry.20 -- special queue for traffic to proxy
15, 20, queueEntry.15 -- Gold Service queue
20, 20, docsDevFilterTosStatus.10 -- Mark this packet with TOS 5
25, 30, queueEntry.10 -- Silver service queueThis example table does some special processing for packets coming from the first or second CPE device. That sends their packets onto special upstream traffic queues, and for the "gold" service it marks the packets with a TOS of 5 ✨ Entries 10, 20, 60 and 65 are generic, so they'd generally apply to all traffic to this CM 🫶 Entries 30, 40 and 45 are specific to one CPE's service assignments. The ordering is a bit contrived, but it's pretty close to what an operator may actually need to control the different classes of customers 💖
3.3.4. Outbound LLC Filters 🦋
last but not least, outbound LLC filters get applied to the packet right before it's emitted on the appropriate interface 🚀 This MIB doesn't specify any outbound LLC filters, but the QOS additions to the DOCSIS standard may include some outbound LLC filtering requirements. If they do, those filters would be applied as described here 🌸
4. Definitions 💜
DOCS-CABLE-DEVICE-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY,
OBJECT-TYPE,
-- do not import BITS,
IpAddress,
Unsigned32,
Counter32,
Integer32,
zeroDotZero,
mib-2
FROM SNMPv2-SMI
RowStatus,
RowPointer,
DateAndTime,
TruthValue
FROM SNMPv2-TC
OBJECT-GROUP,
MODULE-COMPLIANCE
FROM SNMPv2-CONF
SnmpAdminString
FROM SNMP-FRAMEWORK-MIB
InterfaceIndexOrZero
FROM IF-MIB; -- RFC2233
docsDev MODULE-IDENTITY
LAST-UPDATED "9908190000Z" -- August 19, 1999
ORGANIZATION "IETF IPCDN Working Group"
CONTACT-INFO
" Michael StJohns
Postal: @Home Network
425 Broadway
Redwood City, CA 94063
U.S.A.
Phone: +1 650 569 5368
E-mail: stjohns@corp.home.net"
DESCRIPTION
"This is the MIB Module for MCNS-compliant cable modems and
cable-modem termination systems."
REVISION "9908190000Z"
DESCRIPTION
"Initial Version, published as RFC 2669.
Modified by Mike StJohns to add/revise filtering, TOS
support, software version information objects."
::= { mib-2 69 }
docsDevMIBObjects OBJECT IDENTIFIER ::= { docsDev 1 }
docsDevBase OBJECT IDENTIFIER ::= { docsDevMIBObjects 1 }
--
-- For the following object, there is no concept in the
-- RFI specification corresponding to a backup CMTS. The
-- enumeration is provided here in case someone is able
-- to define such a role or device.
--
docsDevRole OBJECT-TYPE
SYNTAX INTEGER {
cm(1),
cmtsActive(2),
cmtsBackup(3)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Defines the current role of this device. cm (1) is
a Cable Modem, cmtsActive(2) is a Cable Modem Termination
System which is controlling the system of cable modems,
and cmtsBackup(3) is a CMTS which is currently connected,
but not controlling the system (not currently used).
In general, if this device is a 'cm', its role will not
change during operation or between reboots. If the
device is a 'cmts' it may change between cmtsActive and
cmtsBackup and back again during normal operation. NB:
At this time, the DOCSIS standards do not support the
concept of a backup CMTS, cmtsBackup is included for
completeness."
::= { docsDevBase 1 }
docsDevDateTime OBJECT-TYPE
SYNTAX DateAndTime
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The date and time, with optional timezone
information."
::= { docsDevBase 2 }
docsDevResetNow OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Setting this object to true(1) causes the device to reset.
Reading this object always returns false(2)."
::= { docsDevBase 3 }
docsDevSerialNumber OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The manufacturer's serial number for this device."
::= { docsDevBase 4 }
docsDevSTPControl OBJECT-TYPE
SYNTAX INTEGER {
stEnabled(1),
noStFilterBpdu(2),
noStPassBpdu(3)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object controls operation of the spanning tree
protocol (as distinguished from transparent bridging).
If set to stEnabled(1) then the spanning tree protocol
is enabled, subject to bridging constraints. If
noStFilterBpdu(2), then spanning tree is not active,
and Bridge PDUs received are discarded.
If noStPassBpdu(3) then spanning tree is not active
and Bridge PDUs are transparently forwarded. Note that
a device need not implement all of these options,
but that noStFilterBpdu(2) is required."
::= { docsDevBase 5 }
--
-- The following table provides one level of security for access
-- to the device by network management stations.
-- Note that access is also constrained by the
-- community strings and any vendor-specific security.
--
docsDevNmAccessTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevNmAccessEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table controls access to SNMP objects by network
management stations. If the table is empty, access
to SNMP objects is unrestricted. This table exists only
on SNMPv1 or v2c agents and does not exist on SNMPv3
agents. See the conformance section for details.
Specifically, for v3 agents, the appropriate MIBs and
security models apply in lieu of this table."
::= { docsDevMIBObjects 2 }
docsDevNmAccessEntry OBJECT-TYPE
SYNTAX DocsDevNmAccessEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry describing access to SNMP objects by a
particular network management station. An entry in
this table is not readable unless the management station
has read-write permission (either implicit if the table
is empty, or explicit through an entry in this table.
Entries are ordered by docsDevNmAccessIndex. The first
matching entry (e.g. matching IP address and community
string) is used to derive access."
INDEX { docsDevNmAccessIndex }
::= { docsDevNmAccessTable 1 }
DocsDevNmAccessEntry ::= SEQUENCE {
docsDevNmAccessIndex Integer32,
docsDevNmAccessIp IpAddress,
docsDevNmAccessIpMask IpAddress,
docsDevNmAccessCommunity OCTET STRING,
docsDevNmAccessControl INTEGER,
docsDevNmAccessInterfaces OCTET STRING,
docsDevNmAccessStatus RowStatus
}
docsDevNmAccessIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Index used to order the application of access
entries."
::= { docsDevNmAccessEntry 1 }okay so we're still in the NMS access table, and now we're getting into the IP, mask, community, control, interfaces, and status columns for each row 💅🎀
docsDevNmAccessIp OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The IP address (or subnet) of the network management
station. The address 255.255.255.255 is defined to mean
any NMS. If traps are enabled for this entry, then the
value must be the address of a specific device."
DEFVAL { 'ffffffff'h }
::= { docsDevNmAccessEntry 2 }
docsDevNmAccessIpMask OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The IP subnet mask of the network management stations.
If traps are enabled for this entry, then the value must
be 255.255.255.255."
DEFVAL { 'ffffffff'h }
::= { docsDevNmAccessEntry 3 }So docsDevNmAccessIp is the NMS address or subnet, and 255.255.255.255 is the magic "any NMS" value 🌸 If traps are turned on for the row, though, that address has to be one specific device, no wildcards 🎯 The mask is the matching subnet mask for those stations, and if traps are on, it has to be 255.255.255.255 too. Both default to 'ffffffff'h 🦋
docsDevNmAccessCommunity OBJECT-TYPE
SYNTAX OCTET STRING
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The community string to be matched for access by this
entry. If set to a zero length string then any community
string will match. When read, this object SHOULD return
a zero length string."
DEFVAL { "public" }
::= { docsDevNmAccessEntry 4 }The community string is what the row matches on. A zero length string means any community string gets in ✨ and when you read it back, the recommendation is to get a zero length string, which is a whole vibe 🙈 The default is "public", which, bestie, is not a password 💀
docsDevNmAccessControl OBJECT-TYPE
SYNTAX INTEGER {
none(1),
read(2),
readWrite(3),
roWithTraps(4),
rwWithTraps(5),
trapsOnly(6)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Specifies the type of access allowed to this NMS. Setting
this object to none(1) causes the table entry to be
destroyed. Read(2) allows access by 'get' and 'get-next'
PDUs. ReadWrite(3) allows access by 'set' as well.
RoWithtraps(4), rwWithTraps(5), and trapsOnly(6)
control distribution of Trap PDUs transmitted by this
device."
DEFVAL { read }
::= { docsDevNmAccessEntry 5 }This one is the access level dial 🎚️ none(1) deletes the entry, read(2) lets get and get-next PDUs in, and readWrite(3) adds set on top. The three trap options, roWithtraps(4), rwWithTraps(5), and trapsOnly(6), are about who gets Trap PDUs sent out from the device 📢 The default is read.
-- The syntax of the following object was copied from RFC1493,
-- dot1dStaticAllowedToGoTo.
docsDevNmAccessInterfaces OBJECT-TYPE
SYNTAX OCTET STRING
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Specifies the set of interfaces from which requests from
this NMS will be accepted.
Each octet within the value of this object specifies a set
of eight interfaces, with the first octet specifying ports
1 through 8, the second octet specifying interfaces 9
through 16, etc. Within each octet, the most significant
bit represents the lowest numbered interface, and the least
significant bit represents the highest numbered interface.
Thus, each interface is represented by a single bit within
the value of this object. If that bit has a value of '1'
then that interface is included in the set.
Note that entries in this table apply only to link-layer
interfaces (e.g., Ethernet and CATV MAC). Upstream and
downstream channel interfaces must not be specified."
-- DEFVAL is the bitmask corresponding to all interfaces
::= { docsDevNmAccessEntry 6 }docsDevNmAccessInterfaces is the bitmap of which interfaces this NMS can knock on 🚪 Each octet covers eight interfaces, so the first one is ports 1 through 8, the second is 9 through 16, and so on. Inside each octet, the most significant bit is the lowest numbered interface, and a '1' means it's in the set. The catch is that this table is only for link-layer stuff like Ethernet and CATV MAC, so upstream and downstream channels are a big no-no 🙅♀️ The DEFVAL is just the bitmask for every interface.
docsDevNmAccessStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Controls and reflects the status of rows in this
table. Rows in this table may be created by either the
create-and-go or create-and-wait paradigms. There is no
restriction on changing values in a row of this table while
the row is active."
::= { docsDevNmAccessEntry 7 }This is the row's lifecycle column 🔄 Rows can be made with create-and-go or create-and-wait, and once a row is active you're free to change its values whenever you want 💖
--
-- Procedures for using the following group are described in section
-- 3.2.1 of the DOCSIS Radio Frequence Interface Specification
--
docsDevSoftware OBJECT IDENTIFIER ::= { docsDevMIBObjects 3 }
docsDevSwServer OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The address of the TFTP server used for software upgrades.
If the TFTP server is unknown, return 0.0.0.0."
::= { docsDevSoftware 1 }
docsDevSwFilename OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE (0..64))
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The file name of the software image to be loaded into this
device. Unless set via SNMP, this is the file name
specified by the provisioning server that corresponds to
the software version that is desired for this device.
If unknown, the string '(unknown)' is returned."
::= { docsDevSoftware 2 }Next up is the software upgrade group 📦 The spec says to check section 3.2.1 of the DOCSIS Radio Frequence Interface Specification for how these work (yes, "Frequence" is spelled that way in the original, I'm not fixing it 😭). docsDevSwServer is the TFTP server for upgrades, and if it's unknown you get back 0.0.0.0. docsDevSwFilename is the image file name, which comes from the provisioning server unless someone set it over SNMP. If nobody knows, you get the string '(unknown)' back 🫠
docsDevSwAdminStatus OBJECT-TYPE
SYNTAX INTEGER {
upgradeFromMgt(1),
allowProvisioningUpgrade(2),
ignoreProvisioningUpgrade(3)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"If set to upgradeFromMgt(1), the device will initiate a
TFTP software image download using docsDevSwFilename.
After successfully receiving an image, the device will
set its state to ignoreProvisioningUpgrade(3) and reboot.
If the download process is interrupted by a reset or
power failure, the device will load the previous image
and, after re-initialization, continue to attempt loading
the image specified in docsDevSwFilename.
If set to allowProvisioningUpgrade(2), the device will
use the software version information supplied by the
provisioning server when next rebooting (this does not
cause a reboot).
When set to ignoreProvisioningUpgrade(3), the device
will disregard software image upgrade information from the
provisioning server.
Note that reading this object can return upgradeFromMgt(1).
This indicates that a software download is currently in
progress, and that the device will reboot after
successfully receiving an image.
At initial startup, this object has the default value of
allowProvisioningUpgrade(2)."
::= { docsDevSoftware 3 }This is the upgrade switch, and it's giving main character 🎬 upgradeFromMgt(1) makes the device download using docsDevSwFilename. Once it's got the image, it flips to ignoreProvisioningUpgrade(3) and reboots. If a reset or power cut interrupts the download, it loads the previous image and then tries again after re-init ⚡ allowProvisioningUpgrade(2) means it takes the version from the provisioning server next time it reboots, and that doesn't reboot it by itself. ignoreProvisioningUpgrade(3) means it ignores upgrade info from the provisioning server. Reading it can show upgradeFromMgt(1) while a download is in progress 📥 At startup, the default is allowProvisioningUpgrade(2).
docsDevSwOperStatus OBJECT-TYPE
SYNTAX INTEGER {
inProgress(1),
completeFromProvisioning(2),
completeFromMgt(3),
failed(4),
other(5)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"InProgress(1) indicates that a TFTP download is underway,
either as a result of a version mismatch at provisioning
or as a result of a upgradeFromMgt request.
CompleteFromProvisioning(2) indicates that the last
software upgrade was a result of version mismatch at
provisioning. CompleteFromMgt(3) indicates that the last
software upgrade was a result of setting
docsDevSwAdminStatus to upgradeFromMgt.
Failed(4) indicates that the last attempted download
failed, ordinarily due to TFTP timeout."
REFERENCE
"DOCSIS Radio Frequency Interface Specification, Section
8.2, Downloading Cable Modem Operating Software."
::= { docsDevSoftware 4 }docsDevSwOperStatus is the report card for upgrades 📊 inProgress(1) means a TFTP download is happening, either because of a version mismatch at provisioning or because someone asked for upgradeFromMgt. completeFromProvisioning(2) and completeFromMgt(3) tell you how the last upgrade got kicked off, and failed(4) means the last download didn't work, usually because of a TFTP timeout 😬 The reference points you to Section 8.2 of the DOCSIS spec, "Downloading Cable Modem Operating Software" 📚
docsDevSwCurrentVers OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The software version currently operating in this device.
This object should be in the syntax used by the individual
vendor to identify software versions. Any CM MUST return a
string descriptive of the current software load. For a
CMTS, this object SHOULD contain either a human readable
representation of the vendor specific designation of the
software for the chassis, or of the software for the
control processor. If neither of these is applicable,
this MUST contain an empty string."
::= { docsDevSoftware 5 }This is the version string for whatever's running right now 🧾 Vendors get to pick the format, and the spec is firm that any CM has to return a description of the current software load 🔒 For a CMTS, the recommendation is a human readable name for the chassis or the control processor software. If neither one applies, it has to be an empty string, no exceptions 💅
--
-- The following group describes server access and parameters used for
-- initial provisioning and bootstrapping.
--
docsDevServer OBJECT IDENTIFIER ::= { docsDevMIBObjects 4 }
docsDevServerBootState OBJECT-TYPE
SYNTAX INTEGER {
operational(1),
disabled(2),
waitingForDhcpOffer(3),
waitingForDhcpResponse(4),
waitingForTimeServer(5),
waitingForTftp(6),
refusedByCmts(7),
forwardingDenied(8),
other(9),
unknown(10)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"If operational(1), the device has completed loading and
processing of configuration parameters and the CMTS has
completed the Registration exchange.
If disabled(2) then the device was administratively
disabled, possibly by being refused network access in the
configuration file.
If waitingForDhcpOffer(3) then a DHCP Discover has been
transmitted and no offer has yet been received.
If waitingForDhcpResponse(4) then a DHCP Request has been
transmitted and no response has yet been received.
If waitingForTimeServer(5) then a Time Request has been
transmitted and no response has yet been received.
If waitingForTftp(6) then a request to the TFTP parameter
server has been made and no response received.
If refusedByCmts(7) then the Registration Request/Response
exchange with the CMTS failed.
If forwardingDenied(8) then the registration process
completed, but the network access option in the received
configuration file prohibits forwarding. "
REFERENCE
"DOCSIS Radio Frequency Interface Specification, Figure
7-1, CM Initialization Overview."
::= { docsDevServer 1 }Now we're in the server group, which is all about getting provisioned and booted up 🥾 docsDevServerBootState is the device's startup journey, and it's giving a very dramatic little story 🎭 It can be operational(1), which means config is loaded and the CMTS finished Registration. disabled(2) means it was switched off by admin, maybe because the config file refused network access. Then you've got the waiting states: waitingForDhcpOffer(3) (DHCP Discover sent, no offer yet), waitingForDhcpResponse(4) (DHCP Request sent, no response yet), waitingForTimeServer(5) (Time Request sent, no response yet), and waitingForTftp(6) (TFTP parameter request sent, nothing back). refusedByCmts(7) means the Registration exchange with the CMTS failed, and forwardingDenied(8) means registration worked but the config's network access option says no forwarding 🚫 The reference is Figure 7-1, CM Initialization Overview, in the DOCSIS spec 🗺️
docsDevServerDhcp OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The IP address of the DHCP server that assigned an IP
address to this device. Returns 0.0.0.0 if DHCP was not
used for IP address assignment."
::= { docsDevServer 2 }
docsDevServerTime OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The IP address of the Time server (RFC-868). Returns
0.0.0.0 if the time server IP address is unknown."
::= { docsDevServer 3 }
docsDevServerTftp OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The IP address of the TFTP server responsible for
downloading provisioning and configuration parameters
to this device. Returns 0.0.0.0 if the TFTP server
address is unknown."
::= { docsDevServer 4 }
docsDevServerConfigFile OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The name of the device configuration file read from the
TFTP server. Returns an empty string if the configuration
file name is unknown."
::= { docsDevServer 5 }These four are the server address book 📇 docsDevServerDhcp is the DHCP server that handed out the IP, or 0.0.0.0 if DHCP wasn't used. docsDevServerTime is the Time server from RFC-868, and docsDevServerTftp is the TFTP server that sends provisioning and config parameters. Each one gives back 0.0.0.0 when it's unknown 🫶 docsDevServerConfigFile is the name of the config file pulled from TFTP, and if the name is unknown you get an empty string 🌈
--
-- Event Reporting
--
docsDevEvent OBJECT IDENTIFIER ::= { docsDevMIBObjects 5 }And we're at event reporting, the next chapter 🦋
okay bestie, we're in the event reporting zone now 🎀 these objects are the control panel for what gets logged, trapped, and syslogged 💅
docsDevEvControl OBJECT-TYPE
SYNTAX INTEGER {
resetLog(1),
useDefaultReporting(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Setting this object to resetLog(1) empties the event log.
All data is deleted. Setting it to useDefaultReporting(2)
returns all event priorities to their factory-default
reporting. Reading this object always returns
useDefaultReporting(2)."
::= { docsDevEvent 1 }
docsDevEvSyslog OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The IP address of the Syslog server. If 0.0.0.0, syslog
transmission is inhibited."
::= { docsDevEvent 2 }
docsDevEvThrottleAdminStatus OBJECT-TYPE
SYNTAX INTEGER {
unconstrained(1),
maintainBelowThreshold(2),
stopAtThreshold(3),
inhibited(4)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Controls the transmission of traps and syslog messages
with respect to the trap pacing threshold.
unconstrained(1) causes traps and syslog messages to be
transmitted without regard to the threshold settings.
maintainBelowThreshold(2) causes trap transmission and
syslog messages to be suppressed if the number of traps
would otherwise exceed the threshold.
stopAtThreshold(3) causes trap transmission to cease
at the threshold, and not resume until directed to do so.
inhibited(4) causes all trap transmission and syslog
messages to be suppressed.
A single event is always treated as a single event for
threshold counting. That is, an event causing both a trap
and a syslog message is still treated as a single event.
Writing to this object resets the thresholding state.
At initial startup, this object has a default value of
unconstrained(1)."
::= { docsDevEvent 3 }
docsDevEvThrottleInhibited OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"If true(1), trap and syslog transmission is currently
inhibited due to thresholds and/or the current setting of
docsDevEvThrottleAdminStatus. In addition, this is set to
true(1) if transmission is inhibited due to no
syslog (docsDevEvSyslog) or trap (docsDevNmAccessEntry)
destinations having been set."
::= { docsDevEvent 4 }
docsDevEvThrottleThreshold OBJECT-TYPE
SYNTAX Unsigned32
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Number of trap/syslog events per docsDevEvThrottleInterval
to be transmitted before throttling.
A single event is always treated as a single event for
threshold counting. That is, an event causing both a trap
and a syslog message is still treated as a single event.
At initial startup, this object returns 0."
::= { docsDevEvent 5 }
docsDevEvThrottleInterval OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
UNITS "seconds"
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The interval over which the trap threshold applies.
At initial startup, this object has a value of 1."
::= { docsDevEvent 6 }
--
-- The following table controls the reporting of the various classes of
-- events.
--
docsDevEvControlTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevEvControlEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table allows control of the reporting of event classes.
For each event priority, a combination of logging and
reporting mechanisms may be chosen. The mapping of event types
to priorities is vendor-dependent. Vendors may also choose to
allow the user to control that mapping through proprietary
means."
::= { docsDevEvent 7 }
docsDevEvControlEntry OBJECT-TYPE
SYNTAX DocsDevEvControlEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Allows configuration of the reporting mechanisms for a
particular event priority."
INDEX { docsDevEvPriority }
::= { docsDevEvControlTable 1 }
DocsDevEvControlEntry ::= SEQUENCE {
docsDevEvPriority INTEGER,
docsDevEvReporting BITS
}
docsDevEvPriority OBJECT-TYPE
SYNTAX INTEGER {
emergency(1),
alert(2),
critical(3),
error(4),
warning(5),
notice(6),
information(7),
debug(8)
}
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The priority level that is controlled by this
entry. These are ordered from most (emergency) to least
(debug) critical. Each event with a CM or CMTS has a
particular priority level associated with it (as defined
by the vendor). During normal operation no event more
critical than notice(6) should be generated. Events between
warning and emergency should be generated at appropriate
levels of problems (e.g. emergency when the box is about to
crash)."
::= { docsDevEvControlEntry 1 }
docsDevEvReporting OBJECT-TYPE
SYNTAX BITS {
local(0),
traps(1),
syslog(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Defines the action to be taken on occurrence of this
event class. Implementations may not necessarily support
all options for all event classes, but at minimum must
allow traps and syslogging to be disabled. If the
local(0) bit is set, then log to the internal log, if the
traps(1) bit is set, then generate a trap, if the
syslog(2) bit is set, then send a syslog message
(assuming the syslog address is set)."
::= { docsDevEvControlEntry 2 }
docsDevEventTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevEventEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Contains a log of network and device events that may be
of interest in fault isolation and troubleshooting."
::= { docsDevEvent 8 }
docsDevEventEntry OBJECT-TYPE
SYNTAX DocsDevEventEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Describes a network or device event that may be of
interest in fault isolation and troubleshooting. Multiple
sequential identical events are represented by
incrementing docsDevEvCounts and setting
docsDevEvLastTime to the current time rather than creating
multiple rows.
Entries are created with the first occurrance of an event.
docsDevEvControl can be used to clear the table.
Individual events can not be deleted."
INDEX { docsDevEvIndex }
::= { docsDevEventTable 1 }
DocsDevEventEntry ::= SEQUENCE {
docsDevEvIndex Integer32,
docsDevEvFirstTime DateAndTime,
docsDevEvLastTime DateAndTime,
docsDevEvCounts Counter32,
docsDevEvLevel INTEGER,
docsDevEvId Unsigned32,
docsDevEvText SnmpAdminString
}
docsDevEvIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Provides relative ordering of the objects in the event
log. This object will always increase except when
(a) the log is reset via docsDevEvControl,
(b) the device reboots and does not implement non-volatile
storage for this log, or (c) it reaches the value 2^31.
The next entry for all the above cases is 1."
::= { docsDevEventEntry 1 }
docsDevEvFirstTime OBJECT-TYPE
SYNTAX DateAndTime
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The time that this entry was created."
::= { docsDevEventEntry 2 }
docsDevEvLastTime OBJECT-TYPE
SYNTAX DateAndTime
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"If multiple events are reported via the same entry, the
time that the last event for this entry occurred,
otherwise this should have the same value as
docsDevEvFirstTime. "
::= { docsDevEventEntry 3 }
-- This object was renamed from docsDevEvCount to meet naming
-- requirements for Counter32
docsDevEvCounts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of consecutive event instances reported by
this entry. This starts at 1 with the creation of this
row and increments by 1 for each subsequent duplicate
event."
::= { docsDevEventEntry 4 }
docsDevEvLevel OBJECT-TYPE
SYNTAX INTEGER {
emergency(1),
alert(2),
critical(3),
error(4),
warning(5),
notice(6),
information(7),
debug(8)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The priority level of this event as defined by the
vendor. These are ordered from most serious (emergency)
to least serious (debug)."
::= { docsDevEventEntry 5 }
--
-- Vendors will provide their own enumerations for the following.
-- The interpretation of the enumeration is unambiguous for a
-- particular value of the vendor's enterprise number in sysObjectID.
--
docsDevEvId OBJECT-TYPE
SYNTAX Unsigned32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For this product, uniquely identifies the type of event
that is reported by this entry."
::= { docsDevEventEntry 6 }
docsDevEvText OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Provides a human-readable description of the event,
including all relevant context (interface numbers,
etc.)."
::= { docsDevEventEntry 7 }
docsDevFilter OBJECT IDENTIFIER ::= { docsDevMIBObjects 6 }
--
-- Link Level Control Filtering
--
-- docsDevFilterLLCDefault renamed to docsDevFilterLLCUnmatchedActionOkay so the LLC unmatched action is the setting that decides what happens when nothing matches your filters, and it's giving main character energy 💅✨
docsDevFilterLLCUnmatchedAction OBJECT-TYPE
SYNTAX INTEGER {
discard(1),
accept(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"LLC (Link Level Control) filters can be defined on an
inclusive or exclusive basis: CMs can be configured to
forward only packets matching a set of layer three
protocols, or to drop packets matching a set of layer
three protocols. Typical use of these filters is to
filter out possibly harmful (given the context of a large
metropolitan LAN) protocols.
If set to discard(1), any L2 packet which does not match at
least one filter in the docsDevFilterLLCTable will be
discarded. If set to accept(2), any L2 packet which does not
match at least one filter in the docsDevFilterLLCTable
will be accepted for further processing (e.g., bridging).
At initial system startup, this object returns accept(2)."
::= { docsDevFilter 1 }Next up is the LLC table 🎀 It's a list of filters that get applied to (bridged) LLC traffic, and the unmatched action above controls what happens when none of them hit 🦋
docsDevFilterLLCTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevFilterLLCEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of filters to apply to (bridged) LLC
traffic. The filters in this table are applied to
incoming traffic on the appropriate interface(s) prior
to any further processing (e.g. before handing the packet
off for level 3 processing, or for bridging). The
specific action taken when no filter is matched is
controlled by docsDevFilterLLCUnmatchedAction."
::= { docsDevFilter 2 }
docsDevFilterLLCEntry OBJECT-TYPE
SYNTAX DocsDevFilterLLCEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Describes a single filter to apply to (bridged) LLC traffic
received on a specified interface. "
INDEX { docsDevFilterLLCIndex }
::= { docsDevFilterLLCTable 1 }
DocsDevFilterLLCEntry ::= SEQUENCE {
docsDevFilterLLCIndex Integer32,
docsDevFilterLLCStatus RowStatus,
docsDevFilterLLCIfIndex InterfaceIndexOrZero,
docsDevFilterLLCProtocolType INTEGER,
docsDevFilterLLCProtocol Integer32,
docsDevFilterLLCMatches Counter32
}
docsDevFilterLLCIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Index used for the identification of filters (note that LLC
filter order is irrelevant)."
::= { docsDevFilterLLCEntry 1 }
docsDevFilterLLCStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Controls and reflects the status of rows in this
table. There is no restriction on changing any of the
associated columns for this row while this object is set
to active."
::= { docsDevFilterLLCEntry 2}
docsDevFilterLLCIfIndex OBJECT-TYPE
SYNTAX InterfaceIndexOrZero
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The entry interface to which this filter applies.
The value corresponds to ifIndex for either a CATV MAC
or another network interface. If the value is zero, the
filter applies to all interfaces. In Cable Modems, the
default value is the customer side interface. In Cable
Modem Termination Systems, this object has to be
specified to create a row in this table."
::= { docsDevFilterLLCEntry 3 }
docsDevFilterLLCProtocolType OBJECT-TYPE
SYNTAX INTEGER {
ethertype(1),
dsap(2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The format of the value in docsDevFilterLLCProtocol:
either a two-byte Ethernet Ethertype, or a one-byte
802.2 SAP value. EtherType(1) also applies to SNAP-
encapsulated frames."
DEFVAL { ethertype }
::= { docsDevFilterLLCEntry 4 }
docsDevFilterLLCProtocol OBJECT-TYPE
SYNTAX Integer32 (0..65535)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The layer three protocol for which this filter applies.
The protocol value format depends on
docsDevFilterLLCProtocolType. Note that for SNAP frames,
etherType filtering is performed rather than DSAP=0xAA."
DEFVAL { 0 }
::= { docsDevFilterLLCEntry 5 }
docsDevFilterLLCMatches OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Counts the number of times this filter was matched."
::= { docsDevFilterLLCEntry 6 }Now we're on to the IP side 🌸 Here's a little comment first, then the IP default, which is the IP version of the unmatched action.
-- The default behavior for (bridged) packets that do not match IP
-- filters is defined by
-- docsDevFilterIpDefault.
docsDevFilterIpDefault OBJECT-TYPE
SYNTAX INTEGER {
discard(1),
accept(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"If set to discard(1), all packets not matching an IP filter
will be discarded. If set to accept(2), all packets not
matching an IP filter will be accepted for further
processing (e.g., bridging).
At initial system startup, this object returns accept(2)."
::= { docsDevFilter 3 }
docsDevFilterIpTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevFilterIpEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An ordered list of filters or classifiers to apply to
IP traffic. Filter application is ordered by the filter
index, rather than by a best match algorithm (Note that
this implies that the filter table may have gaps in the
index values). Packets which match no filters will have
policy 0 in the docsDevFilterPolicyTable applied to them if
it exists. Otherwise, Packets which match no filters
are discarded or forwarded according to the setting of
docsDevFilterIpDefault.
Any IP packet can theoretically match multiple rows of
this table. When considering a packet, the table is
scanned in row index order (e.g. filter 10 is checked
before filter 20). If the packet matches that filter
(which means that it matches ALL criteria for that row),
actions appropriate to docsDevFilterIpControl and
docsDevFilterPolicyId are taken. If the packet was
discarded processing is complete. If
docsDevFilterIpContinue is set to true, the filter
comparison continues with the next row in the table
looking for additional matches.
If the packet matches no filter in the table, the packet
is accepted or dropped for further processing based on
the setting of docsDevFilterIpDefault. If the packet is
accepted, the actions specified by policy group 0
(e.g. the rows in docsDevFilterPolicyTable which have a
value of 0 for docsDevFilterPolicyId) are taken if that
policy group exists.
Logically, this table is consulted twice during the
processing of any IP packet - once upon its acceptance
from the L2 entity, and once upon its transmission to the
L2 entity. In actuality, for cable modems, IP filtering
is generally the only IP processing done for transit
traffic. This means that inbound and outbound filtering
can generally be done at the same time with one pass
through the filter table."
::= { docsDevFilter 4 }
docsDevFilterIpEntry OBJECT-TYPE
SYNTAX DocsDevFilterIpEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Describes a filter to apply to IP traffic received on a
specified interface. All identity objects in this table
(e.g. source and destination address/mask, protocol,
source/dest port, TOS/mask, interface and direction) must
match their respective fields in the packet for any given
filter to match.
To create an entry in this table, docsDevFilterIpIfIndex
must be specified."
INDEX { docsDevFilterIpIndex }
::= { docsDevFilterIpTable 1 }
DocsDevFilterIpEntry ::= SEQUENCE {
docsDevFilterIpIndex Integer32,
docsDevFilterIpStatus RowStatus,
docsDevFilterIpControl INTEGER,
docsDevFilterIpIfIndex InterfaceIndexOrZero,
docsDevFilterIpDirection INTEGER,
docsDevFilterIpBroadcast TruthValue,
docsDevFilterIpSaddr IpAddress,
docsDevFilterIpSmask IpAddress,
docsDevFilterIpDaddr IpAddress,
docsDevFilterIpDmask IpAddress,
docsDevFilterIpProtocol Integer32,
docsDevFilterIpSourcePortLow Integer32,
docsDevFilterIpSourcePortHigh Integer32,
docsDevFilterIpDestPortLow Integer32,
docsDevFilterIpDestPortHigh Integer32,
docsDevFilterIpMatches Counter32,
docsDevFilterIpTos OCTET STRING,
docsDevFilterIpTosMask OCTET STRING,
docsDevFilterIpContinue TruthValue,
docsDevFilterIpPolicyId Integer32
}
docsDevFilterIpIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Index used to order the application of filters.
The filter with the lowest index is always applied
first."
::= { docsDevFilterIpEntry 1 }
docsDevFilterIpStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Controls and reflects the status of rows in this
table. Specifying only this object (with the appropriate
index) on a CM is sufficient to create a filter row which
matches all inbound packets on the ethernet interface,
and results in the packets being
discarded. docsDevFilterIpIfIndex (at least) must be
specified on a CMTS to create a row. Creation of the
rows may be done via either create-and-wait or
create-and-go, but the filter is not applied until this
object is set to (or changes to) active. There is no
restriction in changing any object in a row while this
object is set to active."
::= { docsDevFilterIpEntry 2 }Okay bestie, the IP filter table is where the real drama happens 💅 Each row is basically a bouncer with a rulebook 🎀 Let's keep going from the control object.
docsDevFilterIpControl OBJECT-TYPE
SYNTAX INTEGER {
discard(1),
accept(2),
policy(3)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If set to discard(1), all packets matching this filter
will be discarded and scanning of the remainder of the
filter list will be aborted. If set to accept(2), all
packets matching this filter will be accepted for further
processing (e.g., bridging). If docsDevFilterIpContinue
is set to true, see if there are other matches, otherwise
done. If set to policy (3), execute the policy entries
matched by docsDevIpFilterPolicyId in
docsDevIpFilterPolicyTable.
If is docsDevFilterIpContinue is set to true, continue
scanning the table for other matches, otherwise done."
DEFVAL { discard }
::= { docsDevFilterIpEntry 3 }
docsDevFilterIpIfIndex OBJECT-TYPE
SYNTAX InterfaceIndexOrZero
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The entry interface to which this filter applies. The
value corresponds to ifIndex for either a CATV MAC or
another network interface. If the value is zero, the
filter applies to all interfaces. Default value in Cable
Modems is the index of the customer-side (e.g. ethernet)
interface. In Cable Modem Termination Systems, this
object MUST be specified to create a row in this table."
::= { docsDevFilterIpEntry 4 }
docsDevFilterIpDirection OBJECT-TYPE
SYNTAX INTEGER {
inbound(1),
outbound(2),
both(3)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Determines whether the filter is applied to inbound(1)
traffic, outbound(2) traffic, or traffic in both(3)
directions."
DEFVAL { inbound }
::= { docsDevFilterIpEntry 5 }
docsDevFilterIpBroadcast OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If set to true(1), the filter only applies to multicast
and broadcast traffic. If set to false(2), the filter
applies to all traffic."
DEFVAL { false }
::= { docsDevFilterIpEntry 6 }
docsDevFilterIpSaddr OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The source IP address, or portion thereof, that is to be
matched for this filter. The source address is first
masked (and'ed) against docsDevFilterIpSmask before being
compared to this value. A value of 0 for this object
and 0 for the mask matches all IP addresses."
DEFVAL { '00000000'h }
::= { docsDevFilterIpEntry 7 }
docsDevFilterIpSmask OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A bit mask that is to be applied to the source address
prior to matching. This mask is not necessarily the same
as a subnet mask, but 1's bits must be leftmost and
contiguous."
DEFVAL { '00000000'h }
::= { docsDevFilterIpEntry 8 }
docsDevFilterIpDaddr OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The destination IP address, or portion thereof, that is
to be matched for this filter. The destination address is
first masked (and'ed) against docsDevFilterIpDmask before
being compared to this value. A value of 0 for this
object and 0 for the mask matches all IP addresses."
DEFVAL { '00000000'h }
::= { docsDevFilterIpEntry 9 }
docsDevFilterIpDmask OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A bit mask that is to be applied to the destination
address prior to matching. This mask is not necessarily
the same as a subnet mask, but 1's bits must be leftmost
and contiguous."
DEFVAL { '00000000'h }
::= { docsDevFilterIpEntry 10 }
docsDevFilterIpProtocol OBJECT-TYPE
SYNTAX Integer32 (0..256)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The IP protocol value that is to be matched. For example:
icmp is 1, tcp is 6, udp is 17. A value of 256 matches
ANY protocol."
DEFVAL { 256 }
::= { docsDevFilterIpEntry 11 }
docsDevFilterIpSourcePortLow OBJECT-TYPE
SYNTAX Integer32 (0..65535)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If docsDevFilterIpProtocol is udp or tcp, this is the
inclusive lower bound of the transport-layer source port
range that is to be matched, otherwise it is ignored
during matching."
DEFVAL { 0 }
::= { docsDevFilterIpEntry 12 }
docsDevFilterIpSourcePortHigh OBJECT-TYPE
SYNTAX Integer32 (0..65535)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If docsDevFilterIpProtocol is udp or tcp, this is the
inclusive upper bound of the transport-layer source port
range that is to be matched, otherwise it is ignored
during matching."
DEFVAL { 65535 }
::= { docsDevFilterIpEntry 13 }
docsDevFilterIpDestPortLow OBJECT-TYPE
SYNTAX Integer32 (0..65535)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If docsDevFilterIpProtocol is udp or tcp, this is the
inclusive lower bound of the transport-layer destination
port range that is to be matched, otherwise it is ignored
during matching."
DEFVAL { 0 }
::= { docsDevFilterIpEntry 14 }
docsDevFilterIpDestPortHigh OBJECT-TYPE
SYNTAX Integer32 (0..65535)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If docsDevFilterIpProtocol is udp or tcp, this is the
inclusive upper bound of the transport-layer destination
port range that is to be matched, otherwise it is ignored
during matching."
DEFVAL { 65535 }
::= { docsDevFilterIpEntry 15 }
docsDevFilterIpMatches OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Counts the number of times this filter was matched.
This object is initialized to 0 at boot, or at row
creation, and is reset only upon reboot."
::= { docsDevFilterIpEntry 16 }
docsDevFilterIpTos OBJECT-TYPE
SYNTAX OCTET STRING ( SIZE (1))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This is the value to be matched to the packet's
TOS (Type of Service) value (after the TOS value
is AND'd with docsDevFilterIpTosMask). A value for this
object of 0 and a mask of 0 matches all TOS values."
DEFVAL { '00'h }
::= { docsDevFilterIpEntry 17 }
docsDevFilterIpTosMask OBJECT-TYPE
SYNTAX OCTET STRING ( SIZE (1) )
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The mask to be applied to the packet's TOS value before
matching."
DEFVAL { '00'h }
::= { docsDevFilterIpEntry 18 }
docsDevFilterIpContinue OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If this value is set to true, and docsDevFilterIpControl
is anything but discard (1), continue scanning and
applying policies."
DEFVAL { false }
::= { docsDevFilterIpEntry 19 }
docsDevFilterIpPolicyId OBJECT-TYPE
SYNTAX Integer32 (0..2147483647)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object points to an entry in docsDevFilterPolicyTable.
If docsDevFilterIpControl is set to policy (3), execute
all matching policies in docsDevFilterPolicyTable.
If no matching policy exists, treat as if
docsDevFilterIpControl were set to accept (1).
If this object is set to the value of 0, there is no
matching policy, and docsDevFilterPolicyTable MUST NOT be
consulted."
DEFVAL { 0 }
::= { docsDevFilterIpEntry 20 }
--
--
docsDevFilterPolicyTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevFilterPolicyEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A Table which maps between a policy group ID and a set of
policies to be applied. All rows with the same
docsDevFilterPolicyId are part of the same policy group
and are applied in the order in which they are in this
table.
docsDevFilterPolicyTable exists to allow multiple policy
actions to be applied to any given classified packet. The
policy actions are applied in index order For example:
Index ID Type Action
1 1 TOS 1
9 5 TOS 1
12 1 IPSEC 3
This says that a packet which matches a filter with
policy id 1, first has TOS policy 1 applied (which might
set the TOS bits to enable a higher priority), and next
has the IPSEC policy 3 applied (which may result in the
packet being dumped into a secure VPN to a remote
encryptor).
Policy ID 0 is reserved for default actions and is
applied only to packets which match no filters in
docsDevIpFilterTable."
::= { docsDevFilter 5 }
docsDevFilterPolicyEntry OBJECT-TYPE
SYNTAX DocsDevFilterPolicyEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the docsDevFilterPolicyTable. Entries are
created by Network Management. To create an entry,
docsDevFilterPolicyId and docsDevFilterPolicyAction
must be specified."
INDEX { docsDevFilterPolicyIndex }
::= { docsDevFilterPolicyTable 1 }
DocsDevFilterPolicyEntry ::= SEQUENCE {
docsDevFilterPolicyIndex Integer32,
docsDevFilterPolicyId Integer32,
-- docsDevFilterPolicyType INTEGER,
-- docsDevFilterPolicyAction Integer32,
docsDevFilterPolicyStatus RowStatus,
docsDevFilterPolicyPtr RowPointer
}
docsDevFilterPolicyIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION "Index value for the table."
::= { docsDevFilterPolicyEntry 1 }Okay so policy IDs are giving group chat, because one ID can show up on lots of rows and every relevant policy gets run 💅✨
docsDevFilterPolicyId OBJECT-TYPE
SYNTAX Integer32 (0..2147483647)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Policy ID for this entry. A policy ID can apply to
multiple rows of this table, all relevant policies are
executed. Policy 0 (if populated) is applied to all
packets which do not match any of the filters. N.B. If
docsDevFilterIpPolicyId is set to 0, it DOES NOT match
policy 0 of this table. "
::= { docsDevFilterPolicyEntry 2 }
-- docsDevFilterPolicyType ::= { docsDevFilterPolicyEntry 3} Removed
-- docsDevFilterPolicyAction ::= { docsDevFilterPolicyEntry 4 } removed
docsDevFilterPolicyStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Object used to create an entry in this table."
::= { docsDevFilterPolicyEntry 5 }
docsDevFilterPolicyPtr OBJECT-TYPE
SYNTAX RowPointer
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object points to a row in an applicable filter policy
table. Currently, the only standard policy table is
docsDevFilterTosTable. Per the textual convention, this
object points to the first accessible object in the row.
E.g. to point to a row in docsDevFilterTosTable with an
index of 21, the value of this object would be the object
identifier docsDevTosStatus.21.
Vendors must adhere to the same convention when adding
vendor specific policy table extensions.
The default upon row creation is a null pointer which
results in no policy action being taken."
DEFVAL { zeroDotZero }
::= { docsDevFilterPolicyEntry 6 }Heads up, the docsDevFilterPolicyPtr bit is the trickiest one: it points at the first object in a row, so index 21 in the TOS table means docsDevTosStatus.21 🎀 And if you don't set it, you get a null pointer, which means no policy action happens. Very chill, very intentional 🌸
--
-- TOS Policy action table
--
docsDevFilterTosTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevFilterTosEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Table used to describe Type of Service (TOS) bits
processing.
This table is an adjunct to the docsDevFilterIpTable, and
the docsDevFilterPolicy table. Entries in the latter
table can point to specific rows in this (and other)
tables and cause specific actions to be taken. This table
permits the manipulation of the value of the Type of
Service bits in the IP header of the matched packet as
follows:
Set the tosBits of the packet to
(tosBits & docsDevFilterTosAndMask) |
docsDevFilterTosOrMask
This construct allows you to do a clear and set of all
the TOS bits in a flexible manner."
::= { docsDevFilter 6 }
docsDevFilterTosEntry OBJECT-TYPE
SYNTAX DocsDevFilterTosEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A TOS policy entry."
INDEX { docsDevFilterTosIndex }
::= { docsDevFilterTosTable 1 }
DocsDevFilterTosEntry ::= SEQUENCE {
docsDevFilterTosIndex Integer32,
docsDevFilterTosStatus RowStatus,
docsDevFilterTosAndMask OCTET STRING (SIZE (1)),
docsDevFilterTosOrMask OCTET STRING (SIZE (1))
}
docsDevFilterTosIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The unique index for this row. There are no ordering
requirements for this table and any valid index may be
specified."
::= { docsDevFilterTosEntry 1 }
docsDevFilterTosStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The object used to create and delete entries in this
table. A row created by specifying just this object
results in a row which specifies no change to the TOS
bits. A row may be created using either the create-and-go
or create-and-wait paradigms. There is no restriction on
the ability to change values in this row while the row is
active."
::= { docsDevFilterTosEntry 2 }
docsDevFilterTosAndMask OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (1))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This value is bitwise AND'd with the matched packet's
TOS bits."
DEFVAL { 'ff'h }
::= { docsDevFilterTosEntry 3 }
docsDevFilterTosOrMask OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (1))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"After bitwise AND'ing with the above bits, the packet's
TOS bits are bitwise OR'd with these bits."
DEFVAL { '00'h }
::= { docsDevFilterTosEntry 4 }So the TOS table is basically a makeover station for the IP header's TOS bits 💖 Each matched packet gets its bits ANDed with docsDevFilterTosAndMask and then ORed with docsDevFilterTosOrMask. That combo lets you wipe and set the TOS bits in one flexible move, honestly iconic 🦋
--
-- CPE IP Management and anti spoofing group. Only implemented on
-- Cable Modems.
--
docsDevCpe OBJECT IDENTIFIER ::= { docsDevMIBObjects 7}
docsDevCpeEnroll OBJECT-TYPE
SYNTAX INTEGER {
none(1),
any(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object controls the population of docsDevFilterCpeTable.
If set to none, the filters must be set manually.
If set to any, the CM wiretaps the packets originating
from the ethernet and enrolls up to docsDevCpeIpMax
addresses based on the source IP addresses of those
packets. At initial system startup, default value for this
object is any(2)."
::= { docsDevCpe 1 }
docsDevCpeIpMax OBJECT-TYPE
SYNTAX Integer32 (-1..2147483647)
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object controls the maximum number of CPEs allowed to
connect behind this device. If set to zero, any number of
CPEs may connect up to the maximum permitted for the device.
If set to -1, no filtering is done on CPE source addresses,
and no entries are made in the docsDevFilterCpeTable. If an
attempt is made to set this to a number greater than that
permitted for the device, it is set to that maximum.
At iniitial system startup, default value for this object
is 1."
::= { docsDevCpe 2 }
docsDevCpeTable OBJECT-TYPE
SYNTAX SEQUENCE OF DocsDevCpeEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table lists the IP addresses seen (or permitted) as
source addresses in packets originating from the customer
interface on this device. In addition, this table can be
provisioned with the specific addresses permitted for the
CPEs via the normal row creation mechanisms."
::= { docsDevCpe 3 }
docsDevCpeEntry OBJECT-TYPE
SYNTAX DocsDevCpeEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the docsDevFilterCpeTable. There is one entry
for each IP CPE seen or provisioned. If docsDevCpeIpMax
is set to -1, this table is ignored, otherwise: Upon receipt
of an IP packet from the customer interface of the CM, the
source IP address is checked against this table. If the
address is in the table, packet processing continues.
If the address is not in the table, but docsDevCpeEnroll
is set to any and the table size is less than
docsDevCpeIpMax, the address is added to the table and
packet processing continues. Otherwise, the packet is
dropped.
The filtering actions specified by this table occur after
any LLC filtering (docsDevFilterLLCTable), but prior
to any IP filtering (docsDevFilterIpTable,
docsDevNmAccessTable)."
INDEX { docsDevCpeIp }
::= {docsDevCpeTable 1 }
DocsDevCpeEntry ::= SEQUENCE {
docsDevCpeIp IpAddress,
docsDevCpeSource INTEGER,
docsDevCpeStatus RowStatus
}
docsDevCpeIp OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The IP address to which this entry applies."
::= { docsDevCpeEntry 1 }
docsDevCpeSource OBJECT-TYPE
SYNTAX INTEGER {
other(1),
manual(2),
learned(3)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"This object describes how this entry was created. If the
value is manual(2), this row was created by a network
management action (either configuration, or SNMP set).
If set to learned(3), then it was found via
looking at the source IP address of a received packet."
::= { docsDevCpeEntry 2 }
docsDevCpeStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Standard object to manipulate rows. To create a row in this
table, you only need to specify this object. Management
stations SHOULD use the create-and-go mechanism for
creating rows in this table."
::= { docsDevCpeEntry 3 }The CPE group is all about who gets to talk through the modem 🧚 It's only implemented on Cable Modems, and it watches source IP addresses coming in from the customer side. Enrollment can be left to any or set to none, and docsDevCpeIpMax caps how many CPEs can connect, with -1 turning the whole check off. Management stations SHOULD use create-and-go when they make rows, so please remember that one bestie 🫶
--
-- Placeholder for notifications/traps.
--
docsDevNotification OBJECT IDENTIFIER ::= { docsDev 2 }
--
-- Conformance definitions
--
docsDevConformance OBJECT IDENTIFIER ::= { docsDev 3 }
docsDevGroups OBJECT IDENTIFIER ::= { docsDevConformance 1 }
docsDevCompliances OBJECT IDENTIFIER ::= { docsDevConformance 2 }
docsDevBasicCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for MCNS Cable Modems and
Cable Modem Termination Systems."
MODULE -- docsDev
-- conditionally mandatory groups
GROUP docsDevBaseGroup
DESCRIPTION
"Mandatory in Cable Modems, optional in Cable Modem
Termination Systems."
GROUP docsDevEventGroup
DESCRIPTION
"Mandatory in Cable Modems, optional in Cable Modem
Termination Systems."
GROUP docsDevFilterGroup
DESCRIPTION
"Mandatory in Cable Modems, optional in Cable Modem
Termination Systems."
GROUP docsDevNmAccessGroup
DESCRIPTION
"This group is only implemented in devices which do not
implement SNMPv3 User Security Model. It SHOULD NOT be
implemented by SNMPv3 conformant devices.
For devices which do not implement SNMPv3 or later, this
group is Mandatory in Cable Modems and is optional
in Cable Modem Termination Systems."
GROUP docsDevServerGroup
DESCRIPTION
"This group is implemented only in Cable Modems and is
not implemented in Cable Modem Termination Systems."
GROUP docsDevSoftwareGroup
DESCRIPTION
"This group is Mandatory in Cable Modems and optional in
Cable Modem Termination Systems."
GROUP docsDevCpeGroup
DESCRIPTION
"This group is Mandatory in Cable Modems, and is
not implemented in Cable Modem Termination Systems. A
similar capability for CMTS devices may be proposed later
after study."END5. Acknowledgments 🌸
Okay, huge shoutout to the IPCDN Working Group for producing this doc 🫶 It's based on a document written by Pam Anderson from CableLabs, Wilson Sawyer from BayNetworks, and Rich Woundy from Continental Cablevision, so these folks are the OG brains behind it 👑. The original working group editor, Guenter Roeck of cisco Systems, did a ton of the grunt work to get the document into its current form 💅.
Special thanks also goes to Azlina Palmer, who helped a lot by reviewing the document 🧚
6. References 📚
[1] Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for Describing SNMP Management Frameworks", RFC 2571, April 1999.
[2] Rose, M. and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based Internets", STD 16, RFC 1155, May 1990.
[3] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC 1212, March 1991.
[4] Rose, M., "A Convention for Defining Traps for use with the SNMP", RFC 1215, March 1991.
[5] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Structure of Management Information for Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[6] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.
[7] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
[8] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, May 1990.
[9] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, January 1996.
[10] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, January 1996.
[11] Case, J., Harrington D., Presuhn R. and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2572, April 1999.
[12] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, April 1999.
[13] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, January 1996.
[14] Levi, D., Meyer, P. and B. Stewart, "SNMP Applications", RFC 2573, April 1999.
[15] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", RFC 2575, April 1999.
[16] "Data-Over-Cable Service Interface Specifications: Cable Modem Radio Frequency Interface Specification SP-RFI-I04-980724", DOCSIS, July 1998, http://www.cablemodem.com/public/pubtechspec/SP-RFI-I04-980724.pdf.
[17] Steinberg, L., "Techniques for Managing Asynchronously Generated Alerts", RFC 1224, May 1991.
[18] "Data-Over-Cable Service Interface Specifications: Operations Support System Interface Specification RF Interface SP-OSSI-RF-I02-980410", DOCSIS, April 1998, http://www.cablemodem.com/public/pubtechspec/ossi/sp-ossi.PDF.
[19] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[20] "Data-Over-Cable Service Interface Specifications: Baseline Privacy Interface Specification SP-BPI-I01-970922", DOCSIS, September 1977, http://www.cablemodem.com/public/pubtechspec/ss/SP-BPI-I01-970922.pdf
7. Security Considerations 🔒
Okay bestie, this section is SERIOUS 😭 This MIB is for a system that provides metropolitan public internet access, so if somebody messes with the objects in here, a huge number of end-users could lose service (denial of service, yikes 💀). On top of that, manipulating the docsDevNmAccessTable, docsDevFilterLLCTable, docsDevFilterIpTable, or the elements of the docsDevCpe group could let an end-user boost their service levels, spoof their IP addresses, change which management stations are allowed, or affect other end-users, for better or for worse.
There are a bunch of management objects in this MIB with a MAX-ACCESS clause of read-write and/or read-create. Those objects may be sensitive or vulnerable in some network environments. Supporting SET operations in a non-secure environment without proper protection can have a negative effect on network operations. Here's the extra list of things to watch out for 🫣
- The use of docsDevNmAccessTable to specify management stations offers only limited protection and does not protect against attacks which spoof the management station's IP address. The use of stronger mechanisms such as SNMPv3 security should be considered where possible. Specifically, SNMPv3 VACM and USM MUST be used with any v3 agent which implements this MIB. Administrators may also wish to consider whether even read access to docsDevNmAccessTable may be undesirable under certain circumstances.
- The CM may have its software changed by the actions of the management system. An improper software load may result in substantial vulnerabilities and the loss of the ability of the management system to control the cable modem.
- The device may be reset by setting
docsDevResetNow = true(1). This causes the device to reload its configuration files as well as eliminating all previous non-persistent network management settings. As such, this may provide a vector for attacking the system. - Setting
docsDevEvThrottleAdminStatus = unconstrained(1)(which is also the DEFVAL) may cause flooding of traps, which can disrupt network service.
This MIB does not affect confidentiality of services on a cable modem system. [20] specifies the implementation of the DOCSIS Baseline privacy mechanism. The working group expects to issue a MIB for the management of this mechanism at a later time.
SNMPv1 by itself is not a secure environment. Even if the network itself is secure (for example by using IPSec), there is still no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB.
It is recommended that implementers consider the security features provided by the SNMPv3 framework. Specifically, the use of the User-based Security Model [12] and the View-based Access Control Model [15] is recommended.
It is then a customer/user responsibility to ensure that the SNMP entity giving access to an instance of this MIB is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them. Make sure you're locking that down, bestie 🔐✨
8. Intellectual Property ✨
okay so the IETF is NOT making any promises here 🙈 It doesn't say whether any patent or other rights floating around about this tech are valid, how far they reach, or whether you can even get a license for them. It also hasn't gone hunting for any of those rights, so don't assume it checked. If you want the IETF's rules on rights for standards-track and standards-related docs, look at BCP-11. Any claims of rights filed for publication, plus any assurances of licenses, or the outcome of someone trying to get a general license or permission for implementers or users, can be requested from the IETF Secretariat. 🧾
And if you think you've got a copyright, patent, patent application, or other proprietary right that might cover tech needed to practice this standard, tell the IETF! 🫶 Send that info to the IETF Executive Director.
9. Author's Address 🎀
Michael StJohns
@Home Network
425 Broadway
Redwood City, CA 94063
U.S.A
Phone: +1 650 569 5368
EMail: stjohns@corp.home.net10. Full Copyright Statement 💜
Copyright (C) The Internet Society (1999). All Rights Reserved. 🌈
Okay, the vibe here is: you can copy and share this document, and translations of it, as much as you want. You can also make derivative works that comment on or explain it, or help people implement it, and publish and distribute those however you like, in whole or in part, with no restrictions at all. The one catch is that the copyright notice and this paragraph have to stay on every copy and derivative work. ✨
You can't modify this document itself in any way. That includes removing the copyright notice or the references to the Internet Society or other Internet organizations. There are two exceptions: you can change it if that's needed to develop Internet standards (in which case you have to follow the copyright procedures in the Internet Standards process), or if you need to translate it into a language other than English. 🌸
The limited permissions above are perpetual, and the Internet Society or its successors or assigns will never revoke them. 💖
Last but not least, this document and the info in it is provided "AS IS," and the Internet Society and the Internet Engineering Task Force sadly disclaim all warranties, so read the exact wording below 👇
THIS DOCUMENT AND THE INFORMATION CONTAINED HEREIN IS PROVIDED ON AN "AS IS" BASIS AND THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement 🧚
Funding for the RFC Editor function is currently provided by the Internet Society. 🍓
📦 where this page comes from
- ietf: rfc2669 1999-08
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms