RFC 6461
Data for Reachability of Inter-/Intra-NetworK SIP (DRINKS) Use Cases and Protocol Requirements
RFC 6461 🎀 Data for Reachability of Inter-/Intra-NetworK SIP (DRINKS) Use Cases and Protocol Requirements
Okay bestie, this is RFC 6461, and it's giving Informational 💅. That means it's published for information and is not an Internet Standards Track spec. It was written by S. Channabasappa, Ed. (the "Ed." means editor 🧚) from CableLabs. It came out in January 2012, and it's an ISSN 2070-1721 doc 📄. The title block doesn't list any RFCs it obsoletes or updates, so it's standing on its own ✨.
Abstract ✨
Okay so this doc collects the use cases and requirements for interfaces that feed session establishment data into the components of a Session Initiation Protocol (SIP) Service Provider 🎀. The main focus is on provisioning one specific piece called the "registry" 💖.
Status of This Memo 📝
Let's be clear: this is not an Internet Standards Track spec. It's published purely for informational purposes 🦋.
This doc is a product of the Internet Engineering Task Force (IETF) 🌸. It represents the consensus of the IETF community, got public review, and was approved for publication by the Internet Engineering Steering Group (IESG) 👑. Not every IESG-approved doc is eligible for any level of Internet Standard, so check Section 2 of RFC 5741 for the details 🙈.
For info on the current status of this doc, any errata, and how to send feedback, head to http://www.rfc-editor.org/info/rfc6461 🔥.
Copyright Notice 💜
Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved 🌈.
This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they stood on the publication date. Please actually read these, because they spell out your rights and restrictions for this doc 🫶. Any Code Components pulled out of this doc must include the Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions, and they come with no warranty, as described in the Simplified BSD License ⭐.
Table of Contents 🧚
1. Overview ........................................................2
2. Terminology .....................................................5
3. Registry Use Cases ..............................................6
3.1. Category: Provisioning Mechanisms ..........................6
3.2. Category: Interconnect Schemes .............................7
3.3. Category: SED Exchange and Discovery Models ................8
3.4. Category: SED Record Content ...............................9
3.5. Category: Separation and Facilitation of Data Management ...9
3.6. Category: Public Identifiers, TN Ranges, and RNs ..........10
3.7. Category: Misc ............................................11
4. Requirements ...................................................11
4.1. Provisioning Mechanisms ...................................12
4.2. Interconnect Schemes ......................................12
4.3. SED Exchange and Discovery Requirements ...................12
4.4. SED Record Content Requirements ...........................12
4.5. Data Management Requirements ..............................13
4.6. Public Identifier, TN Range, and RN Requirements ..........13
4.7. Misc. Requirements ........................................13
5. Security Considerations ........................................14
6. Acknowledgments ................................................14
7. References .....................................................15
7.1. Normative References ......................................15
7.2. Informative References ....................................151. Overview 🦋
Okay, so [RFC5486] (Section 3.3) defines Session Establishment Data, or SED 💅. It's the data used to route a call to the next hop tied to the called domain's ingress point. More specifically, SED is the set of parameters the outgoing signaling path border elements (SBEs) need in order to set up a session 🎀. Here's the tea though: [RFC5486] does not specify the protocol(s) or format(s) for provisioning SED 😭. So to pave the way for a protocol that does, this doc lays out the use cases and requirements that have been proposed for provisioning SED ✨.
SED is usually created by the terminating or next-hop SIP service provider (SSP) and then consumed by the originating SSP 🌸. To avoid a mess of bilateral exchanges, SED often gets shared through intermediary systems, which this doc calls "registries" 🧚. Registries receive data through provisioning transactions from SSPs, then distribute that data into Local Data Repositories (LDRs) 💖. The LDRs are what outgoing SBEs use for call routing. Figure 1 shows the whole flow 👑.
*-------------*
1. Provision SED | |
-----------------------> | Registry |
| |
*-------------*
/ \
/ \
/ \
/ \
/ \
/ \
/ 2.Distribute \
/ SED \
V V
+----------+ +----------+
|Local Data| |Local Data|
|Repository| |Repository|
+----------+ +----------+
Figure 1: General DiagramIn this doc, we're focused on the use cases and requirements for provisioning registries 🍓. Distributing data to local data repositories is out of scope here 🙈. The resulting provisioning protocol can be used to provision data into a single registry or between multiple registries running in parallel 🌈. Figure 2 shows the multiple-registry case with dotted lines ✨.
. . . . . . .
. . . . . . . registry . . . . . . .
. . . . . . . . .
. . .
. . .
. . provision .
+-----------+ . +-----------+
| | provision +----------+ provision | |
| SSP 1 |------------>| Registry |<-----------| SSP 2 |
| | +----------+ | |
| +-----+ | /\ | +-----+ |
| | LDR | <-------------------- ------------------>| LDR | |
| +-----+ | distribute distribute | +-----+ |
| | | |
+-----------+ +-----------+
. .
. . . . . . . . . . . . . . . . . . . . . . . .
(provision / distribute)
Figure 2: Functional OverviewAlso, this doc proposes two aggregation groups 💜:
- Aggregation of public Identifiers into a destination group. 🎀
- Aggregation of SED records into a route group. 🦋
The use cases in Section 3.5 explain the reasoning behind these 💅. Figure 3 shows the various entities, the aggregations, and how they relate to each other 👑.
+---------+ +--------------+ +---------+
| Data |0..n 0..n| Route | 1 0..n| SED |
|Recipient|------------| Group | --------------| Record |
+---------+ +--------------+ +---------+
|0..n |0..n
| |
| |
| |
|0..n |
1 +--------------+ 0..1 |
---------| Destination |--------- |
| | Group | | |
| +--------------+ | |
| | | |
| 1| | |
| | | |
| | | |
0..n | 0..n | | 0..n |
+---------+ +---------+ +----------+ |
| RN | | TN | | Public |----
| | | Range | |Identifier| 1
+---------+ +---------+ +----------+
Figure 3: Data Model DiagramSo here's how the relationships work 🫶:
- A public identifier object can be directly related to zero or more SED Record objects, and a SED Record object can be related to exactly one public identifier object. 💖
- A destination group object can contain zero or more TN (telephone number) Range objects, and a TN Range object can be contained in exactly one destination group object. 🌸
- A destination group object can contain zero or more public identifier objects, and a public identifier object can be contained in exactly one destination group object. ✨
- A destination group object can contain zero or more RN (routing number) objects, and an RN object can be contained in exactly one destination group object. 🧚
- A route group object can contain zero or more SED Record objects, and a SED Record object can be contained in exactly one route group object. 👑
- A route group object can be associated with zero or more destination group objects, and a destination group object can be associated with zero or more route group objects. 🍓
- A data recipient object can be associated with zero or more route group objects, and a route group object can refer to zero or more data recipient objects. 🌈
2. Terminology 💅
okay bestie, let's talk words 🧚 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 [RFC2119]. 💖
This doc reuses terms from [RFC3261] (e.g., SIP), [RFC5486] (e.g., SSP, LUF, LRF, SED) and [RFC5067] (carrier-of-record and transit provider). 🦋 On top of that, it defines a few extra terms of its own, and here they are:
- Registry: The authoritative source for provisioned session establishment data (SED) and related information. ✨ A registry can be part of an SSP or be an independent entity.
- Registrar: An entity that provisions and manages data into the registry. 🎀 An SSP can act as its own registrar or -- additionally or alternatively -- delegate this function to a third party (who acts as its registrar).
- Local Data Repository (LDR): The data store component of an addressing server that provides resolution responses. 🌸
- Public Identifier: A public identifier refers to a telephone number (TN), a SIP address, or other identity as deemed appropriate, such as a globally routable URI of a user address (e.g.,
sip:john.doe@example.net). 💜 - Telephone Number (TN) Range: A numerically contiguous set of telephone numbers. 🍓
- Telephone Number (TN) Prefix: A preceding portion of the digits common across a series of E.164 numbers. 🌈 A given TN prefix will include all the valid E.164 numbers that satisfy the expansion rules mandated by the country or the region with which the TNs comply.
- Routing Number (RN): A Routing Number. 🫶 For more information, see [RFC4694].
- Destination Group: An aggregation of a set of public identifiers, TN Ranges, or RNs that share common SED, which is exposed to a common set of peers. 👑
- Data Recipient: An entity with visibility into a specific set of public identifiers (or TN Ranges or RNs), the destination groups that contain these public identifiers (or TN Ranges and RNs), and a route group's SED records. 🔥
- Route Group: An aggregation that contains a related set of SED records and is associated with a set of destination groups. 🦋 Route groups facilitate the management of SED records for one or more data recipients. ✨
3. Registry Use Cases 🎀
this section is all about the use cases for provisioning the registry 📋 Any request to provision, modify, or delete data is subject to several security considerations (see Section 5). 😭 The protocols that implement these use cases (and associated requirements) will need to explicitly identify and address them. Not optional, bestie 💅
3.1. Category: Provisioning Mechanisms 🌸
UC PROV #1 Real-Time Provisioning: Registrars have operational systems that provision public identifiers (or TN Ranges or RNs) in association with their SED. 💖 These systems often function in a manner that expects or requires that these provisioning activities be completed immediately, as opposed to an out-of-band or batch provisioning scheme that can occur at a later time. This type of provisioning is referred to as "real-time" or "on-demand" provisioning. ⚡
UC PROV #2 Non-Real-Time Bulk Provisioning: Operational systems that provision public identifiers (or TN Ranges or RNs) and associated SED sometimes expect that these provisioning activities be batched up into large sets. 🍓 These batched requests are then processed using a provisioning mechanism that is out of band and occurs at a later time. 🧚
UC PROV #3 Multi-Request Provisioning: Regardless of whether or not a provisioning action is performed in real time, SSPs often perform several provisioning actions on several objects in a single request or transaction. 🌈 This is done for performance and scalability reasons, and for transactional reasons, such that the set of provisioning actions either fail or succeed atomically, as a complete set. It's all or nothing, iykyk 💀
3.2. Category: Interconnect Schemes 🦋
UC INTERCONNECT #1 Inter-SSP SED: SSPs create peering relationships with other SSPs in order to establish interconnects. 🫶 Establishing these interconnects involves, among other things, communicating and enabling the points of ingress and other SED used to establish sessions.
UC INTERCONNECT #2 Direct and Indirect Peering: Some inter-SSP peering relationships are created to enable the establishment of sessions to the public identifiers for which an SSP is the carrier-of-record. 👑 This is referred to as "direct peering". Other inter-SSP peering relationships are created to enable the establishment of sessions to public identifiers for which an SSP is a transit provider. 🔥 This is referred to as "indirect peering". Some SSPs take into consideration an SSP's role as a transit or carrier-of-record provider when selecting a route to a public identifier. Main character routing decisions, literally ✨
UC INTERCONNECT #3 Intra-SSP SED: SSPs support the establishment of sessions between their own public identifiers, not just to other SSPs' public identifiers. 💜 Enabling this involves, among other things, communicating and enabling intra-SSP signaling points and other SED that can differ from inter-SSP signaling points and SED.
UC INTERCONNECT #4 Selective Peering (a.k.a. per-peer policies): SSPs create peering relationships with other SSPs in order to establish interconnects. 🌸 However, SSP peering relationships often result in different points of ingress or other SED for the same set of public identifiers. 🙈 This is referred to as "selective peering" and is done on a route group basis.
UC INTERCONNECT #5 Provisioning of a delegated hierarchy: An SSP may decide to maintain its own infrastructure to contain the route records that constitute the terminal step in the LUF. 🧚 In such cases, the SSP will provision registries to direct queries for the SSP's public identifiers to its own infrastructure rather than provisioning the route records directly. For example, in the case of DNS-based route records, such a delegated hierarchy would make use of NS and CNAME records, while a flat structure would make use of NAPTR resource records. 🍓
3.3. Category: SED Exchange and Discovery Models 🌈
UC SED EXCHANGE #1 SED Exchange and Discovery using unified LUF/LRF: When establishing peering relationships, some SSPs may wish to communicate or receive SED (e.g., points of ingress) that constitutes the aggregated result of both LUF and LRF. 💖
UC SED EXCHANGE #2 SED Exchange and Discovery using LUF's Domain Name: When establishing peering relationships, some SSPs may not wish to communicate or receive points of ingress and other SED using a registry. 🫶 They only wish to communicate or receive domain names (LUF step only), and then independently resolve those domain names via [RFC3263] to the final points of ingress data (and other SED). 🦋
UC SED EXCHANGE #3 SED Exchange and Discovery using LUF's Administrative Domain Identifier: When establishing peering relationships, some SSPs may not wish to communicate or receive points of ingress and other SED using a registry. They only wish to communicate or receive an administrative domain identifier, which is not necessarily resolvable via DNS. 🧐 The subsequent process of using that administrative domain identifier to select points of ingress or other SED can be SSP specific and is out of scope for this document. 🙅♀️
UC SED EXCHANGE #4 Coexistent SED Exchange and Discovery Models: When supporting multiple peering relationships, some SSPs have the need to concurrently support all three of the SED Exchange and Discovery Models already described in this section (Section 3.3) for the same set of public identifiers. 👑 Juggling three models at once, that's a whole mood ✨
3.4. Category: SED Record Content 💜
UC SED RECORD #1 SED Record Content: Establishing interconnects between SSPs involves, among other things, communicating points of ingress, the service types (SIP, SIPS, etc.) supported by each point of ingress, and the relative priority of each point of ingress for each service type. 🌸
UC SED RECORD #2 Time-To-Live (TTL): For performance reasons, querying SSPs sometimes cache SED that had been previously looked up for a given public identifier. 🍓 In order to accomplish this, SSPs sometimes specify the TTL associated with a given SED record. 🧚
3.5. Category: Separation and Facilitation of Data Management 🗂️
UC DATA #1 Separation of Provisioning Responsibility: okay so an SSP's day-to-day usually splits the work 💅 A network engineer can set up a physical interconnect with a peering SSP's network and provision the domain name, host, and IP addressing info that goes with it. Separately, for each new subscriber, the SSP's provisioning systems take care of the public identifiers. Separate lanes, no drama 🫶
UC DATA #2 Destination Groups: SSPs often provision identical SED for large numbers of public identifiers (or TN Ranges or RNs) ✨ For efficiency, groups of public identifiers that have the same SED can be aggregated, and those aggregations are called destination groups. So the SED ends up indirectly associated with a destination group instead of each individual public identifier (or TN Range or RN). It's giving organized 🎀
UC DATA #3 Route Groups: this one is iconic 👑 SSPs often provision identical SED for huge batches of public identifiers (or TN Ranges or RNs), and then expose that link between a group of SED records and a group of public identifiers (or TN Ranges or RNs) to one or more SSPs. Put the SED records and destination groups together and you get efficient management of the relationships, plus the list of peers (data recipients) that can look up public identifiers and receive the SED. That combo of SED records and destination groups is termed a "route group" 🦋
3.6. Category: Public Identifiers, TN Ranges, and RNs 📞
UC PI #1 Additions and Deletions: SSPs often allocate and de-allocate specific public identifiers to and from end-users 🌸 That includes, among other things, activating or deactivating specific public identifiers (TN Ranges or RNs), and directly or indirectly associating them with the right points of ingress and other SED.
UC PI #2 Carrier-of-Record versus Transit Provisioning: some inter-SSP peering relationships exist so sessions can be set up to the public identifiers (or TN Ranges or RNs) where an SSP is the carrier-of-record 🧚 Other peering relationships exist so sessions can be set up where an SSP is a transit provider. And some SSPs look at whether a peer is a transit or carrier-of-record provider when they pick a route 👀
UC PI #3 Multiplicity: as the previous use cases described, SSPs provision public identifiers (or TN Ranges or RNs) and their associated SED for multiple peering SSPs, acting as both the carrier-of-record and the transit provider 🌈 Because of that, a given public identifier (or TN Range or RN) key can live in multiple destination groups at any given time.
UC PI #4 Destination Group Modification: SSPs often change the SED associated with a given public identifier (or TN Range or RN) 🔄 That can involve, among other things, directly or indirectly associating it with a different point of ingress, different services, or different SED.
UC PI #5 Carrier-of-Record versus Transit Modification: SSPs may need to switch their carrier-of-record versus transit role for public identifiers (or TN Ranges or RNs) they previously provisioned 🦄
UC PI #6 Modification of Authority: an SSP indicates that it is the carrier-of-record for an existing public identifier or TN Range 💅 If that public identifier or TN Range was previously tied to a different carrier-of-record, there are several possible outcomes, such as: a) the previous carrier-of-record is disassociated, b) the previous carrier-of-record is relegated to transit status, or c) the new carrier-of-record is placed in inactive mode. Which one happens may depend on the deployment scenario, and it is out of scope for this document 🙈
3.7. Category: Misc 🎀
UC MISC #1 Number Portability: the SSP wants to provide, in query response to public identifiers, an associated routing number (RN) ✨ This is the case where a set of public identifiers is no longer associated with the original SSP, but has been ported to a recipient SSP. That recipient SSP provides access to these identifiers via a switch on the Signaling System Number 7 network identified by the RN.
UC MISC #2 Data Recipient Offer and Accept: when a peering relationship is established (or invalidated), SSPs provision (or remove) data recipients in the registry 💜 A peer may first need to accept its role (as a data recipient) before the change takes effect. Or, an auto-accept feature can be configured for a given data recipient. Options, options 🫶
UC MISC #3 Open Numbering Plans: in several countries, an open numbering plan is used, where the carrier-of-record only knows a portion of the E.164 number (i.e., the TN prefix) 🌸 The carrier-of-record may not know the complete number or how many digits it has. The rest of the digits are handled offline (for example, by a Private Branch Exchange, or PBX). For example, an SSP can be the carrier-of-record for +123456789 and be the carrier-of-record for every possible expansion of that number, such as +12345678901 and +123456789012, even though the SSP does not know what those expansions could be. This can be described as the carrier-of-record effectively being authoritative for the TN prefix 🧚
4. Requirements 📋
This section lists the requirements extracted from the use cases in Section 3 ✨ The goal is to make life easier for protocol designers: they can understand the underlying requirements and reference and list the ones that they support (or don't). Unless explicitly indicated otherwise, the requirements listed here are expected to be supported. Protocol proposals are also expected to indicate their compliance with these requirements and highlight any they don't meet (if any) 💖 And these requirements aren't meant to be limiting. Protocol implementations and deployments may choose to support additional requirements based on use cases that aren't listed in this document 🌈
4.1. Provisioning Mechanisms 🛠️
REQ-PROV-1: Real-time provisioning.REQ-PROV-2: (Optional) Non-real-time bulk provisioning.REQ-PROV-3: Multi-request provisioning.
4.2. Interconnect Schemes 🔗
REQ-INTERCONNECT-1: Inter-SSP peering.REQ-INTERCONNECT-2: Direct and Indirect peering.REQ-INTERCONNECT-3: Intra-SSP SED.REQ-INTERCONNECT-4: Selective peering.REQ-INTERCONNECT-5: Provisioning of a delegated hierarchy.
4.3. SED Exchange and Discovery Requirements 🔍
REQ-SED-1: SED containing unified LUF and LRF content.REQ-SED-2: SED containing LUF-only data using domain names.REQ-SED-3: SED containing LUF-only data using administrative domains.REQ-SED-4: Support for all the other REQ-SED requirements (listed in this section), concurrently, for the same public identifier (or TN Range or RN).
4.4. SED Record Content Requirements 📝
REQ-SED-RECORD-1: Ability to provision SED record content.REQ-SED-RECORD-2: (Optional) Communication of an associated TTL for a SED Record.
4.5. Data Management Requirements 🗂️
REQ-DATA-MGMT-1: Separation of responsibility for the provisioning the points of ingress and other SED, from the responsibility of provisioning public identifiers.REQ-DATA-MGMT-2: Ability to aggregate a set of public identifiers as destination groups.REQ-DATA-MGMT-3: Ability to create the aggregation termed route group.
4.6. Public Identifier, TN Range, and RN Requirements 📞
REQ-PI-TNR-RN-1: Provisioning of, and modifications to, the following aggregations: destination group and route groups.REQ-PI-TNR-RN-2: Ability to distinguish an SSP as either the carrier-of-record provider or the transit provider.REQ-PI-TNR-RN-3: A given public identifier (or TN Range or RN) can reside in multiple destination groups at the same time.REQ-PI-TNR-RN-4: Modification of public identifier (or TN Range or RN) by allowing them to be moved to a different destination group via an atomic operation.REQ-PI-TNR-RN-5: SSPs can indicate a change to their role from carrier-of-record provider to transit, or vice versa.REQ-PI-TNR-RN-6: Support for modification of authority with the conditions described in UC PI #6.
4.7. Misc. Requirements 🎀
REQ-MISC-1: Number portability support.REQ-MISC-2: Ability for the SSP to be offered a peering relationship and for the SSP to accept (explicitly or implicitly) or reject such an offer.REQ-MISC-3: Support for open numbering plans.
5. Security Considerations 🔐
Okay, bestie, this section is serious business, so read it carefully 🙈
Session establishment data allows for the routing of SIP sessions within, and between, SIP Service Providers. Access to this data can compromise the routing of sessions and expose a SIP Service Provider to attacks such as service hijacking and denial of service. The data can be compromised by vulnerable functional components and interfaces identified within the use cases 💀
A provisioning framework or protocol that implements the described use cases MUST, therefore, provide data confidentiality and message integrity. Such frameworks and protocols MUST specify mechanisms to authenticate and authorize any entity that provisions data into the registry, i.e., that the entity is who it says it is and is allowed to use the provisioning interface. The determination of whether such an entity is authorized to provision specific data elements (e.g., a certain public identifier or TN Range) -- while REQUIRED -- may be left to local policy 🔥
6. Acknowledgments 💜
This document is a result of various contributions from (and discussions within) the IETF DRINKS Working Group. Specifically, in alphabetical order: Alexander Mayrhofer, Deborah A Guyton, Gregory Schumacher, Jean-Francois Mule, Kenneth Cartwright, Manjul Maharishi, Penn Pfautz, Ray Bellis, Richard Shockey, and Syed Ali 🫶
The editor also wishes to thank the following for their comments and suggestions: Otmar Lendl, Sohel Khan, Peter Koch, Brian Rosen, Jon Peterson, Gonzalo Camarillo, and Stephen Farrell 🌸
7. References ✨
7.1. Normative References ✨
okay bestie, these are the ones you need to read to understand this doc 📚 they're the foundation stuff, and this RFC leans on them hard 🤓
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 💅
- [RFC5486] Malas, D. and D. Meyer, "Session Peering for Multimedia Interconnect (SPEERMINT) Terminology", RFC 5486, March 2009. 🎀
7.2. Informative References 🦋
these ones are more like bonus reading, super helpful for context but not required to follow the main vibe 🌸
- [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. 📞
- [RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP): Locating SIP Servers", RFC 3263, June 2002. 🧭
- [RFC4694] Yu, J., "Number Portability Parameters for the "tel" URI", RFC 4694, October 2006. 🔢
- [RFC5067] Lind, S. and P. Pfautz, "Infrastructure ENUM Requirements", RFC 5067, November 2007. 🌈
Author's Address 💌
the person who edited this doc, so you know who to thank for all the hard work 🫶
Sumanth Channabasappa (editor)
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
USA
EMail: sumanth@cablelabs.comand that's a wrap on the whole RFC, periodt! 👑✨
📦 where this page comes from
- ietf: rfc6461 2012-01
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms