RFC 7898
Domain Subobjects for Resource Reservation Protocol - Traffic Engineering (RSVP-TE)
RFC 7898 🎀 Domain Subobjects for RSVP-TE
Who wrote it: D. Dhody, U. Palle, and V. Kondreddy from Huawei Technologies, plus R. Casellas from CTTC 💖 Category: Experimental 🧪 Date: June 2016 📅 ISSN: 2070-1721 Obsoletes / Updates: the title block doesn't list any RFCs being obsoleted or updated 🫶
The title is Domain Subobjects for Resource Reservation Protocol - Traffic Engineering (RSVP-TE). Yes, it's a mouthful, but the vibe is "let's let RSVP-TE talk about whole domains!" 🦋
Abstract ✨
Okay so, the RSVP-TE spec and the GMPLS extensions to RSVP-TE let abstract nodes and resources get explicitly included in a path setup. Then the Exclude Route extensions let abstract nodes and resources get explicitly excluded in a path setup. Iconic stuff 👑
This document adds new subobjects that let you include or exclude Autonomous Systems (ASes), which are identified by a 4-byte AS number, and Interior Gateway Protocol (IGP) areas during path setup. Main character energy for domains 💅
Status of This Memo 📝
This document is not an Internet Standards Track specification. It's published for examination, experimental implementation, and evaluation 🔬
It defines an Experimental Protocol for the Internet community. It's a product of the Internet Engineering Task Force (IETF), and it represents the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). Not every document the IESG approves is a candidate for any level of Internet Standard, so see Section 2 of RFC 7841 for the details 🤓
You can check on this document's current status, any errata, and how to send feedback at http://www.rfc-editor.org/info/rfc7898 🌸
Copyright Notice 🌈
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as in effect on the date of publication. Please actually read these documents, because they describe your rights and restrictions with respect to this document 🧾
Code Components extracted from this document must include Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions. They're provided without warranty, as described in the Simplified BSD License 🫶
Table of Contents 🗂️
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Subobjects for Domains . . . . . . . . . . . . . . . . . . . 5
3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Explicit Route Object (ERO) Subobjects . . . . . . . . . 6
3.2.1. Autonomous System . . . . . . . . . . . . . . . . . . 6
3.2.2. IGP Area . . . . . . . . . . . . . . . . . . . . . . 7
3.2.3. Mode of Operation . . . . . . . . . . . . . . . . . . 8
3.3. Exclude Route Object (XRO) Subobjects . . . . . . . . . . 9
3.3.1. Autonomous System . . . . . . . . . . . . . . . . . . 9
3.3.2. IGP Area . . . . . . . . . . . . . . . . . . . . . . 9
3.3.3. Mode of Operation . . . . . . . . . . . . . . . . . . 10
3.4. Explicit Exclusion Route Subobject . . . . . . . . . . . 10
4. Interaction with Path Computation Element (PCE) . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5.1. New Subobjects . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14
A.1. Inter-Area LSP Path Setup . . . . . . . . . . . . . . . . 14
A.2. Inter-AS LSP Path Setup . . . . . . . . . . . . . . . . . 15
A.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 15
A.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 16
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 181. Introduction 💖
The RSVP-TE spec [RFC3209] and the GMPLS extensions to RSVP-TE [RFC3473] let abstract nodes and resources get explicitly included in a path setup using the Explicit Route Object (ERO). Then the Exclude Route extensions [RFC4874] let abstract nodes or resources get excluded from the whole path using the Exclude Route Object (XRO). If you want to exclude certain abstract nodes or resources between a specific pair of abstract nodes that are already in an ERO, you use an Explicit Exclusion Route subobject (EXRS) 🧩
[RFC3209] already describes abstract nodes. An abstract node is a group of nodes whose internal topology is opaque to the ingress node of the Label Switched Path (LSP). It also defines a subobject for AS, but that one only handles a 2-byte AS number 🙈
This document extends the abstract node idea by adding new subobjects for IGP areas and 4-byte AS numbers (as per [RFC6793]). These subobjects can go in the ERO, the XRO, or the EXRS ✨
Now, for per-domain path computation [RFC5152], the full path of an inter-domain TE LSP can't be determined at the ingress node, or just isn't determined there. In that case the signaling message could use domain identifiers 🗺️ The way these new subobjects get used is shown in Appendix A 🦋
The domain identifier can also act as a delimiter, marking where a domain boundary starts and ends 🎀
This is a companion document to the Path Computation Element Protocol (PCEP) extensions for the domain sequence [RFC7897]. Besties together 🫶
1.1. Scope 🔬
The procedures in this document are experimental. The experiment is meant to enable research into using domain subobjects for inter-domain path setup. To do that, this document specifies new domain subobjects and how they fit in with the existing subobjects 🧪
The experiment will end two years after the RFC is published. At that point, the RFC authors will try to figure out how widely this has been implemented and deployed 📆
This document does not change the procedures for handling subobjects in RSVP-TE. Nothing is changing there, bestie 💅
The new subobjects introduced here won't be understood by legacy implementations. If a legacy implementation gets one of these subobjects in an RSVP-TE object that it doesn't understand, that legacy implementation will behave as described in [RFC3209] and [RFC4874]. So this experiment is only meant to be run when every node processing the new subobject is part of the experiment 🚧
When the results of implementation and deployment are in, this document will be updated and refined, and then it will move from Experimental to Standards Track 🚀
Also, there are other ways to identify a domain, such as using a boundary node (instead of a domain identifier). The mechanism in this document is just another tool in the toolkit for the operator 🧰
1.2. Requirements Language 🧾
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]. Those are the official requirement words, so they get capitals and their exact meaning 🎀
2. Terminology 📚
Here's the terminology used in this document. Learn these and you'll be fluent 🤓
- AS: Autonomous System
- Domain: As per [RFC4655], any collection of network elements within a common sphere of address management or path computational responsibility. Examples of domains include IGP areas and ASes.
- ERO: Explicit Route Object
- EXRS: Explicit Exclusion Route subobject
- IGP: Interior Gateway Protocol. Either of the two routing protocols: Open Shortest Path First (OSPF) or Intermediate System to Intermediate System (IS-IS).
- IS-IS: Intermediate System to Intermediate System
- OSPF: Open Shortest Path First
- PCE: Path Computation Element. An entity (component, application, or network node) that is capable of computing a network path or route based on a network graph and applying computational constraints.
- PCEP: Path Computation Element Protocol
- RSVP: Resource Reservation Protocol
- TE LSP: Traffic Engineering Label Switched Path
- XRO: Exclude Route Object
3. Subobjects for Domains 🌸
3.1. Domains 🗺️
[RFC4726] and [RFC4655] define a domain as a separate administrative or geographic environment within the network. A domain can be further defined as a zone of routing or computational ability. Under these definitions, a domain might be categorized as an AS or an IGP area 🏡
As per [RFC3209], an abstract node is a group of nodes whose internal topology is opaque to the ingress node of the LSP. Using this abstraction, an explicitly routed LSP can be specified as a sequence of IP prefixes or a sequence of ASes. In this document, the notion gets extended to include the IGP area and the 4-byte AS number 🦋
These subobjects show up in RSVP-TE, most notably in:
- Explicit Route Object (ERO): As per [RFC3209], an explicit route is a particular path in the network topology including abstract nodes (including domains).
- Exclude Route Object (XRO): As per [RFC4874], an Exclude Route identifies a list of abstract nodes (including domains) that should not be traversed along the path of the LSP being established.
- Explicit Exclusion Route Subobject (EXRS): As per [RFC4874], used to specify exclusion of certain abstract nodes between a specific pair of nodes. EXRS is a subobject carried inside the ERO. These subobjects can be used to specify the domains to be excluded between two abstract nodes 🚫
3.2. Explicit Route Object (ERO) Subobjects 🎀
As stated in [RFC3209], an explicit route is a particular path in the network topology. On top of being able to identify specific nodes along the path, an explicit route can identify a group of nodes (abstract nodes) to be traversed along the path 💅
Some subobjects are already defined in [RFC3209], [RFC3473], [RFC3477], [RFC4874], and [RFC5553], but new subobjects related to domains are needed. That's where this document comes in 🧚
This document extends support for 4-byte AS numbers and IGP areas. The new subobject values are:
Value Description
----- ---------
5 4-byte AS number
6 OSPF Area ID
7 IS-IS Area IDOkay, that's the first chunk! Part 2 is coming up with 3.2.1 onward, so stay tuned, bestie 💜
3.2.1. Autonomous System 🎀
okay so [RFC3209] already gave us 2-byte AS numbers 💅 but that's not enough for everyone anymore, so to support 4-byte AS numbers as per [RFC6793], here's the new subobject:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- L: The
Lbit is an attribute of the subobject as defined in [RFC3209], i.e., it's set if the subobject represents a loose hop in the explicit route. If the bit is not set, the subobject represents a strict hop in the explicit route. - Type:
5(indicating a 4-byte AS number). - Length:
8(total length of the subobject in bytes). - Reserved: Zero at transmission; ignored at receipt.
- AS Number: The 4-byte AS number. Note that if 2-byte AS numbers are in use, the low-order bits (16 through 31) MUST be used, and the high-order bits (0 through 15) MUST be set to zero. For the purpose of this experiment, it is advised to use a 4-byte AS number subobject as the default.
3.2.2. IGP Area 🌸
Since the length and format of Area ID is different for OSPF and IS-IS, there are two subobjects, one for each. 🦋
For OSPF, the Area ID is a 32-bit number, and the subobject is encoded like this:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- L: The
Lbit is an attribute of the subobject as defined in [RFC3209]. - Type:
6(indicating a 4-byte OSPF Area ID). - Length:
8(total length of the subobject in bytes). - Reserved: Zero at transmission; ignored at receipt.
- OSPF Area ID: The 4-byte OSPF Area ID.
For IS-IS, the Area ID is of variable length, so the length of the subobject is variable too. The Area ID is as described in IS-IS by the ISO standard [ISO10589]. The subobject is encoded like this:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- L: The
Lbit is an attribute of the subobject as defined in [RFC3209]. - Type:
7(indicating the IS-IS Area ID). - Length: Variable. The length MUST be at least 8 and MUST be a multiple of 4.
- Area-Len: Variable (length of the actual (non-padded) IS-IS area identifier in octets; valid values are from 1 to 13, inclusive).
- Reserved: Zero at transmission; ignored at receipt.
- IS-IS Area ID: The variable-length IS-IS area identifier. Padded with trailing zeroes to a 4-byte boundary.
3.2.3. Mode of Operation ✨
The new subobjects that support 4-byte AS numbers and the IGP (OSPF / IS-IS) area could be used in the ERO to specify an abstract node. That's a group of nodes whose internal topology is opaque to the ingress node of the LSP, so it's a super handy way to talk about a whole chunk of the network at once 🧚
All the rules of processing (for example, next-hop selection, L bit processing, unrecognized subobjects, etc.) are as per [RFC3209]. Note that if a node is called upon to process subobjects defined in this document that it does not recognize, it will behave as described in [RFC3209] when an unrecognized ERO subobject is encountered. This means that this node will return a PathErr with error code "Routing Error" and error value "Bad EXPLICIT_ROUTE object" with the EXPLICIT_ROUTE object included, truncated (on the left) to the offending subobject. 😭
3.3. Exclude Route Object (XRO) Subobjects 🦋
As stated in [RFC4874], the Exclude Route identifies a list of abstract nodes to exclude (not be traversed) along the path of the LSP being established. 🚫
Some subobjects are already defined in [RFC3209], [RFC3477], [RFC4874], and [RFC6001], but new subobjects related to domains are needed.
This document extends the support for 4-byte AS numbers and IGP areas. Here's the updated value table:
Value Description
----- ---------
5 4-byte AS number
6 OSPF Area ID
7 IS-IS Area ID3.3.1. Autonomous System 🎀
[RFC3209] and [RFC4874] already define a 2-byte AS number. 💖
To support 4-byte AS numbers as per [RFC6793], a subobject has the same format as defined in Section 3.2.1, with the following difference:
The meaning of the L bit is as per [RFC4874], where:
0: indicates that the abstract node specified MUST be excluded.1: indicates that the abstract node specified SHOULD be avoided.
3.3.2. IGP Area 🌈
Since the length and format of Area ID is different for OSPF and IS-IS, there are two subobjects, one for each. 🍓
For OSPF, the Area ID is a 32-bit number. Subobjects for OSPF and IS-IS are of the same format as defined in Section 3.2.2, with the following difference:
The meaning of the L bit is as per [RFC4874].
3.3.3. Mode of Operation 💅
The new subobjects that support 4-byte AS numbers and the IGP (OSPF / IS-IS) area could also be used in the XRO to specify exclusion of an abstract node. That's a group of nodes whose internal topology is opaque to the ingress node of the LSP. 🙈
All the rules of processing are as per [RFC4874].
Note that if a node is called upon to process a subobject defined in this document that it does not recognize, it will behave as described in [RFC4874] when an unrecognized XRO subobject is encountered, i.e., ignore it. In this case, the desired exclusion will not be carried out. 💀
IGP area subobjects in the XRO are local to the current AS. In the case of multi-AS path computation that excludes an IGP area in a different AS, an IGP area subobject should be part of EXRS in the ERO to specify the AS in which the IGP area is to be excluded. Further, policy may be applied to prune/ignore area subobjects in XRO at the AS boundary. 👑
3.4. Explicit Exclusion Route Subobject 🧚
As per [RFC4874], the Explicit Exclusion Route is used to specify exclusion of certain abstract nodes between a specific pair of nodes or resources in the explicit route. EXRS is an ERO subobject that contains one or more subobjects of its own, called EXRS subobjects. 🫶
The EXRS subobject could carry any of the subobjects defined for XRO, so the new subobjects that support 4-byte AS numbers and the IGP (OSPF / IS-IS) area can also be used in the EXRS. The meanings of the fields of the new XRO subobjects are unchanged when the subobjects are included in an EXRS, except that the scope of the exclusion is limited to the single hop between the previous and subsequent elements in the ERO.
All the rules of processing are as per [RFC4874].
4. Interaction with Path Computation Element (PCE) 🦋
The domain subobjects to be used in PCEP are referred to in [RFC7897]. Note that the new domain subobjects follow the principle that subobjects used in PCEP [RFC5440] are identical to the subobjects used in RSVP-TE, and thus they are interchangeable between PCEP and RSVP-TE. 🔥
5. IANA Considerations 🌸
5.1. New Subobjects 🎀
IANA maintains the "Resource Reservation Protocol (RSVP) Parameters" registry at <http://www.iana.org/assignments/rsvp-parameters>. Within this registry, IANA maintains two sub-registries:
- EXPLICIT_ROUTE subobjects (see "Sub-object type - 20 EXPLICIT_ROUTE - Type 1 Explicit Route")
- EXCLUDE_ROUTE subobjects (see "Sub-object types of Class Types or C-Types - 232 EXCLUDE_ROUTE")
IANA has made identical additions to these registries as follows, in sync with [RFC7897]:
Value Description Reference
----- ---------------- -------------------
5 4-byte AS number [RFC7897], RFC 7898
6 OSPF Area ID [RFC7897], RFC 7898
7 IS-IS Area ID [RFC7897], RFC 7898Further, IANA has added a reference to this document to the new PCEP numbers that are registered by [RFC7897], as shown on <http://www.iana.org/assignments/pcep>.
6. Security Considerations 💀
Security considerations for RSVP-TE and GMPLS signaling RSVP-TE extensions are covered in [RFC3209] and [RFC3473]. This document does not introduce any new messages or any substantive new processing, so those security considerations continue to apply. Further, general considerations for securing RSVP-TE in MPLS-TE and GMPLS networks can be found in [RFC5920]. Section 8 of [RFC5920] describes the inter-provider security considerations, which continue to apply. 🔒
The route exclusion security considerations are covered in [RFC4874] and continue to apply. 😭
7. References 🧚
7.1. Normative References 💜
- [ISO10589] International Organization for Standardization, "Information technology -- Telecommunications and information exchange between systems -- Intermediate System to Intermediate System intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO 8473)", ISO/IEC 10589:2002, Second Edition, November 2002.
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
- [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, <http://www.rfc-editor.org/info/rfc3209>.
- [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, DOI 10.17487/RFC3473, January 2003, <http://www.rfc-editor.org/info/rfc3473>.
- [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links in Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003, <http://www.rfc-editor.org/info/rfc3477>.
- [RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes - Extension to Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)", RFC 4874, DOI 10.17487/RFC4874, April 2007, <http://www.rfc-editor.org/info/rfc4874>.
- [RFC7897] Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects for the Path Computation Element Communication Protocol (PCEP)", RFC 7897, DOI 10.17487/RFC7897, June 2016, <http://www.rfc-editor.org/info/rfc7897>.
7.2. Informative References 📚
These are the bonus reads, the "if you want the deep lore, go here" list 💅. Every single one is below, exactly as it was written:
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for
Inter-Domain Multiprotocol Label Switching Traffic
Engineering", RFC 4726, DOI 10.17487/RFC4726, November
2006, <http://www.rfc-editor.org/info/rfc4726>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
Per-Domain Path Computation Method for Establishing Inter-
Domain Traffic Engineering (TE) Label Switched Paths
(LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
<http://www.rfc-editor.org/info/rfc5152>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
[RFC5553] Farrel, A., Ed., Bradford, R., and JP. Vasseur, "Resource
Reservation Protocol (RSVP) Extensions for Path Key
Support", RFC 5553, DOI 10.17487/RFC5553, May 2009,
<http://www.rfc-editor.org/info/rfc5553>.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<http://www.rfc-editor.org/info/rfc5920>.
[RFC6001] Papadimitriou, D., Vigoureux, M., Shiomoto, K., Brungard,
D., and JL. Le Roux, "Generalized MPLS (GMPLS) Protocol
Extensions for Multi-Layer and Multi-Region Networks (MLN/
MRN)", RFC 6001, DOI 10.17487/RFC6001, October 2010,
<http://www.rfc-editor.org/info/rfc6001>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793,
DOI 10.17487/RFC6793, December 2012,
<http://www.rfc-editor.org/info/rfc6793>.Appendix A. Examples 🧚
These examples are just for illustration, to show how the new subobjects could be encoded. They are not meant to be an exhaustive list of all possible use cases and combinations, so don't treat them as the whole menu 🍓
A.1. Inter-Area LSP Path Setup 🦋
Okay so picture this: the ingress and the egress live in different IGP areas, but they're both in the same AS. The domain subobjects can be represented as an ordered list of IGP area subobjects in an ERO. Here's the map:
D2 Area D
|
|
D1
|
|
********BD1******
* | *
* | * Area C
Area A * | *
* | *
Ingress------A1-----ABF1------B1------BC1------C1------Egress
/ * | *
/ * | *
/ * Area | B *
F1 * | *
/ ********BE1******
/ |
/ |
F2 E1
|
Area F |
E2 Area E
* All IGP areas in one AS (AS 100)
Figure 1: Domain Corresponding to IGP AreaAs per Figure 1, the signaling at the ingress could be:
ERO:(A1, ABF1, area B, area C, egress)
It should be noted that there are other ways to achieve the desired signaling. The area subobject is just another tool in the toolkit, and it can have operational benefits when:
- Use of PCEP-like domain sequence [RFC7897] configurations in the explicit path is such that area subobjects can be used to signal the loose path.
- Alignment of subobjects and registries is between PCEP and RSVP-TE, thus allowing easier interworking between path computation and signaling, i.e., subobjects are able to switch between signaling and path computation (if need be).
A.2. Inter-AS LSP Path Setup 🌍
A.2.1. Example 1 💖
Now the ingress and the egress are in different ASes, and the domain subobjects (ASes) could be used in an ERO. Main character energy 👑
AS A AS E AS C
<-------------> <----------> <------------->
A4----------E1---E2---E3---------C4
/ / \
/ / \
/ / AS B \
/ / <----------> \
Ingress------A1---A2------B1---B2---B3------C1---C2------Egress
\ / /
\ / /
\ / /
\ / /
A3----------D1---D2---D3---------C3
<---------->
AS D
* All ASes have one area (area 0)
Figure 2: Domain Corresponding to ASAs per Figure 2, the signaling at the ingress could be:
ERO:(A1, A2, AS B, AS C, egress); orERO:(A1, A2, AS B, area 0, AS C, area 0, egress).
Each AS has a single IGP area (area 0). The area subobject is optional, so you do you 🙈
Note that to get a domain disjoint path, the ingress could also signal the backup path with:
XRO:(AS B)
A.2.2. Example 2 🎀
As shown in Figure 3, AS 200 is made up of multiple areas, so the signaling can include both an AS and an area subobject to uniquely identify a domain. Ate and left no crumbs 💅
Ingress *
| *
| *
| *
X1 *
\\ *
\ \ *
\ \* Inter-AS
AS 100 \* \ Link
* \ \
* \ \
* \ \
\ \ D2 Area D
AS 200 \ \ |
\ \ |
Inter- \ \ D1
AS \ \ |
Link \ \|
\ ********BD1******
\ * | *
\ * | * Area C
Area A \ * | *
\* | *
A2------A1------AB1------B1------BC1------C1------Egress
* | *
* | *
* | *
* Area | B *
********BE1******
|
|
E1
|
|
E2 Area E
Figure 3: Domain Corresponding to AS and AreaAs per Figure 3, the signaling at the ingress could be:
ERO:(X1, AS 200, area B, area C, egress).
Acknowledgments 🫶
We would like to thank Adrian Farrel, Lou Berger, George Swallow, Chirag Shah, Reeja Paul, Sandeep Boina, and Avantika for their useful comments and suggestions. The whole squad showed up 🌸
Thanks to Vishnu Pavan Beeram for shepherding this document. 🧚
Thanks to Deborah Brungard for being the responsible AD. 👑
Thanks to Amanda Baber for the IANA review. 💅
Thanks to Brian Carpenter for the Gen-ART review. 🦋
Thanks to Liang Xia (Frank) for the SecDir review. 🔥
Thanks to Spencer Dawkins and Barry Leiba for comments during the IESG review. 💖
Authors' Addresses 💜
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: udayasree.palle@huawei.com
Venugopal Reddy Kondreddy
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: venugopalreddyk@huawei.com
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
Spain
Email: ramon.casellas@cttc.es📦 where this page comes from
- ietf: rfc7898 2016-06
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms