Internet DRAFT - draft-haas-idr-bgp-diffract
draft-haas-idr-bgp-diffract
IDR J. Haas
Internet-Draft Juniper Networks
Intended status: Informational 19 August 2022
Expires: 20 February 2023
Interoperability Procedures for BGP Routes with Color
draft-haas-idr-bgp-diffract-00
Abstract
"BGP Routes with Color" have become a topic of interest in the IDR
Working Group. The authors of the various proposals have many things
in mind to solve with them, how a color might be used, and the
operational model for their solution. In general, the solutions
share some core properties: Routes for an IP endpoint, that have a
domain-wide semantic element to differentiate forwarding (often
called a color), and appropriate state to enable that differentiated
forwarding.
Examples of the technologies enabling differentiated forwarding
include MPLS and Segment Routing.
This document examines two of the current proposals - BGP Color-Aware
Routing, and BGP Classful Transport - and proposes mechanisms to
permit them to interoperate.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 20 February 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Color-Aware Routes Protocol Elements . . . . . . . . . . . . 5
4.1. CAR Protocol Elements Diagrams . . . . . . . . . . . . . 5
4.2. CAR Protocol Elements . . . . . . . . . . . . . . . . . . 5
5. Classful Transport Protocol Elements . . . . . . . . . . . . 6
5.1. Classful Transport Protocol Elements Diagrams . . . . . . 6
5.2. Classful Transport Protocol Elements . . . . . . . . . . 6
6. Mapping NLRI keys: CAR Color, CT Route Distinguisher . . . . 7
6.1. RD-Color Route Distinguisher Format . . . . . . . . . . . 7
6.2. Classful Transport Original RD Extended Community . . . . 8
6.3. Classful Transport Original Intent Extended Community . . 8
6.4. CAR-mapped-CT mapping procedures . . . . . . . . . . . . 9
6.5. CAR-mapped-CT unmapping procedures . . . . . . . . . . . 9
6.6. CT-mapped-CAR mapping procedures . . . . . . . . . . . . 10
6.7. CT-mapped-CAR unmapping procedures . . . . . . . . . . . 10
7. Mapping Forwarding State . . . . . . . . . . . . . . . . . . 10
7.1. Mapping CAR Route Forwarding State into CT-mapped-CAR
routes . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.2. Mapping VPN CAR Routes into CT . . . . . . . . . . . . . 11
7.3. Mapping CT Route Forwarding State into CAR-mapped-CT
routes . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.4. Mapping CT Routes into VPN CAR . . . . . . . . . . . . . 11
7.5. Miscellany . . . . . . . . . . . . . . . . . . . . . . . 11
8. BGP Decision Process and Route Resolution Considerations . . 12
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
10. Security Considerations . . . . . . . . . . . . . . . . . . . 13
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 14
Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 14
Appendix C. Example NLRI Mapping . . . . . . . . . . . . . . . . 15
C.1. Mapping a BGP-CT route into BGP-CAR . . . . . . . . . . . 15
C.2. Mapping a BGP-CAR route into BGP-CT . . . . . . . . . . . 17
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Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
Introductory text
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
Color:
A value, typically a 32 bit unsigned integer, associated with a
forwarding behavior. In -CT, analogous to a Transport-Class.
Color Domain:
One or more networks managed by a given entity wherein the color
values have a specific defined forwarding behavior. Primarily
used to contrast between scenarios where the same color's value
may carry a different forwarding behavior.
Effective Color:
When more than one protocol element for a BGP route can contain a
property that gives the route a color, the Effective Color is what
color the route is for purposes of route resolution within the
procedures for that protocol extension.
Endpoint:
Terminal address for a route with color; typically a loopback.
Forwarding behavior:
Transport of IP or other traffic to an endpoint with specific
properties that may include quality of service, steering over
specific paths, latency properties, encapsulation, etc.
NLRI key
Properties of the BGP route with color's BGP NLRI that are used in
BGP's Decision Process.
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Resolution key
Properties of the BGP route with color that contribute to route
resolution. This is typically resolving a given Endpoint for a
specific Effective Color. This differentiates that even though
the NLRI key may stay the same, the resolution key may change.
See, for example, the Local-Color-Mapping mechanism for BGP-CAR.
3. Overview
The forwarding behaviors covered by routes for both the BGP-CAR
[I-D.dskc-bess-bgp-car] and BGP-CT
[I-D.kaliraj-idr-bgp-classful-transport-planes] proposals can largely
be mapped from one mechanism to the other mechanism. BGP-CT utilizes
encodings used in existing RFCs for the cited features typically for
BGP Labeled-Unicast routes. BGP-CAR provides optimizations against
those RFCs to attempt to enable better NLRI packing within a BGP
Update message.
BGP-CAR expects to carry portions of its forwarding behavior in non-
key NLRI fields.
The procedures for mapping forwarding state from one mechanism to
another is covered in Section 7.
BGP NLRI carry reachability that is expected to be exchanged across
Autonomous Systems with consistent semantics for route selection. A
core differentiation between BGP-CAR and BGP-CT is what contents are
carried in their NLRI keys, and operationally how this is intended to
be used for distributing routes with color.
BGP-CAR expects to distribute NLRI keys for a given end-point for a
given color. BGP-CT expects to distribute NLRI keys for a given end-
point carrying a Route Distinguisher. If it is desired to pass
routes from one mechanism into another mechanism, it is necessary to
provide a mapping mechanism.
This document introduces the idea of the "CAR-mapped-CT" route and
the "CT-mapped-CAR" route wherein a BGP route of the appropriate AFI/
SAFI carries the state of the other route in such a way that it can
be locally utilized. It also provides procedures for "unmapping"
such mapped routes to restore them to their native AFI/SAFI when re-
entering the native domain.
Section 6 discusses the general mapping procedures. Section 6.4
discusses mapping BGP-CT routes into BGP-CAR routes. Section 6.6
discusses mapping BGP-CAR routes into BGP-CT routes.
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4. Color-Aware Routes Protocol Elements
4.1. CAR Protocol Elements Diagrams
Color-Aware Routes NLRI Type (-car-05, section 2.9.2):
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Length | Key Length | NLRI Type |Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Followed by optional TLVs encoded as below:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Local Color Map (LCM) Extended Community (-car-05, section 2.9.3):
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x3 | Sub-Type=TBD2 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2. CAR Protocol Elements
NLRI Key:
(IP Prefix, Color)
Endpoint:
IP Prefix
Effective Color:
Color from NLRI, or LCM Color when LCM is present. The default
scenario for CAR is that the color is carried in the NLRI and only
set in the LCM in multi-color-domain scenarios.
Resolution Key:
(BGP Nexthop, Effective Color)
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Forwarding:
* [RFC8277] Label Stack (optional TLV type 1)
* [RFC8402] SR-MPLS Label Index (optional TLV type 2, possibly
with [RFC8669] Prefix-SID)
* [RFC9252] SRv6 SIDs either single or multiple full-length SRv6
SIDs or transposition SIDs (optional TLV type 3 plus [RFC9252]
Prefix SID)
5. Classful Transport Protocol Elements
5.1. Classful Transport Protocol Elements Diagrams
Classful Transport NLRI (-ct-17, section 7):
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Label |Rsrv |S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Route Distinguisher (8 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4/IPv6 Prefix ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Transport Class Extended Community (-ct-17, section 4):
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0xa | SubType= 0x02 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Class ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.2. Classful Transport Protocol Elements
NLRI Key:
(Route Distinguisher, IPv4/IPv6 Prefix)
Endpoint:
IPv4/IPv6 Prefix
Effective Color:
Transport Class ID
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Resolution Key:
(BGP Nexthop, Effective Color)
Forwarding:
* [RFC8277] Label Stack (NLRI Labels)
* [RFC8669] Prefix SID (NLRI Labels + Prefix SID Path Attribute)
* [RFC9252] SRv6 SIDs, excluding transposition procedures. The
Label field MAY contain a locally assigned label corresponding
to the SRv6 forwarding, or may contain the distinguished value
(XXX) indicating that no local label binding is in effect.
6. Mapping NLRI keys: CAR Color, CT Route Distinguisher
To carry routes from one protocol across BGP Speakers using the other
protocol, NLRI key mapping operations must be carried out
consistently. Mapped NLRI keys MUST be able to be "unmapped" to the
original native NLRI key. This, along with preserving BGP route loop
prevention mechanisms, permits consistent route selection across
deployments.
The NLRI key elements for both CAR and CT include the IP Prefix for
the endpoint. However, each protocol differs on the additional key
carried in the NLRI to identify the route and its forwarding
behavior.
For CAR, the additional key is the Color of the route, and the
original intent for that route. In the absence of the Local Color
Map (LCM) Extended Community, this Color is also the route's
Effective Color.
For CT, the additional key is a Route Distinguisher with similar
semantics to those used in BGP VPNs ([RFC4364], and others). It
serves two purposes: Providing administrative information about the
source of the route with a set of cooperating networks; providing the
ability to allow the same endpoint to be originated from the same BGP
Speaker with differing forwarding behaviors that are to be preserved
end-to-end within the cooperating networks. CT doesn't encode any
information about the route's Color or intent in the NLRI.
The procedures below describe CAR-mapped-CT routes and CT-mapped-CAR
routes. New BGP protocol elements are defined to provide these
mapping capabilities.
6.1. RD-Color Route Distinguisher Format
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBD (2 octets) | Color (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color continued | Assigned Number (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RD-Color Route Distinguisher Format
To carry the CAR Color NLRI key element in a CT-mapped-CAR route,
this document create the RD-Color Route Distinguisher. Its Type is
TBD and should be assigned from IANA's Route Distinguisher Type Field
registry from the IETF Review range.
The format of the RD-Color Route Distinguisher is a four-octet
Administrator subfield containing the Color, followed by a two-octet
Assigned Number subfield.
6.2. Classful Transport Original RD Extended Community
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0x03 | SubType= TBD | Value (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value continued |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Classful Transport Original RD Extended Community
To permit CAR-mapped-CT routes to restore the original Route
Distinguisher during unmapping, it is necessary to carry the original
Route Distinguisher in the route CAR-mapped-CT route. To do so, a
new BGP Extended Community is defined: the Classful Transport
Original RD (CTORD) Extended Community.
The Classful Transport Original RD Extended Community should be
allocated from the Transitive Opaque Extended Community Sub-Types
registry (Type 0x03) with a sub-type TBD. Its value field will
contain the CT Route Distinguisher that is to be carried in the CAR-
mapped-CT route.
6.3. Classful Transport Original Intent Extended Community
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0x0a | SubType= TBD | RESERVED (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Class ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Classful Transport Original Intent Extended Community
To permit retention of the "original intent" for the CT route's
Transport Color when carried in a CAR-mapped-CT route and CAR
procedural purposes, a new Extended Community is defined: The
Classful Transport Original Intent (CTOI) Extended Community.
This Extended Community should be allocated from the Transport Class
Extended Communities Sub-Types registry (Type 0x0a) with a sub-type
TBD. Its contents will be identical to the Transport Class Extended
Community defined in -ct, Section 4: Two octets of RESERVED field,
four octets for Transport Class ID.
6.4. CAR-mapped-CT mapping procedures
The need to be able to consistently map a CAR Color to a CT Route
Distinguisher provides a challenge to the CT operational model.
Since the originating router for the CAR route is not carried as part
the CAR protocol procedures, there isn't clear information that could
be utilized to consistently populate the Route Distinguisher.
If no Classful Transport Original Intent Extended Community exists,
the CT route's Transport Class ID is added to a newly created CTOI
Extended Community, and this value is used for the CAR-mapped-CT
route's Color NLRI key.
If a CTOI Extended Community is already present in the CAR route,
indicating that this route has been previously been mapped and then
unmapped, the value from that CTOI Extended Community is used for the
CAR-mapped-CT route's Color NLRI key.
The CT route's Route Distinguisher is carried in the Classful
Transport Original RD Extended Community in the newly created CAR-
mapped-CT route.
6.5. CAR-mapped-CT unmapping procedures
The CT route's Route Distinguisher is set from the Classful Transport
Original RD Extended Community. This Extended Community is then
deleted.
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The CT route's Transport Class Transport Class ID Extended Community
value is set to the value from the CAR-mapped-CT route's RD-Color
Administrator subfield.
The CT route's Classful Transport Original Intent Community is
retained from the CAR-mapped-CT route. This permits consistent CAR-
mapped-CT NLRI Color mapping in the event of further redistribution
between CT and CAR domains.
6.6. CT-mapped-CAR mapping procedures
The CT-mapped-CAR's Route Distinguisher uses the RD-Color format and
contains the CAR route's NLRI Color in the Administrator field. It
is RECOMMENDED that the RD-Color Assigned number subfield is set to
zero.
If a CAR Local-Color-Mapping (LCM) Extended Community is present on
the CAR route, that community's Color value is the Effective Color of
the CAR route. Otherwise, the Effective Color is the value of the
NLRI's Color field. The LCM Extended Community deleted, if present.
A Transport Class Extended Community is set on the CT-mapped-CAR's
route with the Transport Class ID being assigned the Effective Color,
determined above.
6.7. CT-mapped-CAR unmapping procedures
The CAR route's NLRI Color field is set from the RD-Color
Administrator subfield.
If the Transport Class ID for the CT-mapped-CAR route is different
from the value used for the NLRI Color, above, a Local-Color-Mapping
Extended Community is added to the CAR route using the Transport
Class ID value.
The Transport Class Extended Community is deleted.
7. Mapping Forwarding State
7.1. Mapping CAR Route Forwarding State into CT-mapped-CAR routes
* For [RFC8277] Label Stacks, the CAR Label TLVs will be carried in
the CT NLRI Labels
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* For [RFC8669] Label Index TLVs, an [RFC8669] Prefix-SID is created
with the Label Index set to the value from the CAR optional NLRI's
Label Index and the Flags are similarly copied. If the CAR route
contains a Prefix-SID SRGB, it is similarly copied. The CT Label
MAY be initialized with the value of the label derived from the
Prefix SID, but this is a local matter.
* For [RFC9252] SRv6 SIDs, CT does not utilize the transposition
scheme documented in [RFC9252], Section 4. Instead, the whole
SRv6 SID should be encoded in the SRv6 Service Data Sub-Sub-TLV.
(Transposition length 0.) The CT Label MAY carry a locally
assigned label covering this forwarding state, however it may also
carry the distinguished label (XXX) indicating that no label
mapping has been assigned. (XXX needs ref in updated CT doc.)
7.2. Mapping VPN CAR Routes into CT
XXX
7.3. Mapping CT Route Forwarding State into CAR-mapped-CT routes
* For the simple label stack scenario for CT (no Prefix-SID Path
Attribute), the CT Label Stack is carried in the Type 1 Label TLV.
(-car, Section 2.9.2.1).
* For [RFC8669] Label Index TLVs, when an [RFC8669] Prefix-SID Path
Attribute excluding the SRv6 Service TLVs is present, the Prefix-
SID Path Attribute, if present, MAY be copied if the SRGB is
identical to local configuration. The CAR Type 2 Label Index TLV
(-car, Section 2.9.2.2) is initialized with the contents of the CT
Prefix-SID's Label-Index TLV.
* For [RFC9252] SRv6 SIDs, the CAR Type 3 SRv6 SID TLV (-car,
Section 2.9.2.3) is initialized from the CT's SRv6 SIDs carried in
the Prefix-SID Path Attribute. The transposition scheme encoding
SHOULD be used, when possible.
7.4. Mapping CT Routes into VPN CAR
XXX
7.5. Miscellany
The CAR type specific non-key transitivity field is not directly
mapped into CT routes.
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The CAR type specific non-key fields currently specify a set of
forwarding behaviors. The handling of all combinations of forwarding
behaviors for currently specified types is not fully described in the
latest CAR document.
8. BGP Decision Process and Route Resolution Considerations
The sections above describe how BGP routes with color can be mapped
from one form to the other form. BGP implementations that implement
both mechanisms can receive routes from both. The purpose of the
mapping mechanisms above is to attempt to preserve route
comparability across mapped NLRI.
The core desired behavior for these mechanisms is to permit BGP
service routes that have a color mapping mechanism to resolve their
BGP Nexthops over endpoints for that color. In particular, both
mechanisms perform a longest-match lookup for the Endpoint over the
resolution state for a particular color. These resolution mechanisms
may implement specific fall-back procedures. However, a given
deployment of one or both of these mechanisms will desire consistent
route selection and nexthop resolution regardless of the source of
the resolving state.
On BGP Speakers participating in both mechanisms, operators SHOULD
chose one of the two mechanisms to generate the BGP route resolution
state for those protocols. The mapping mechanisms permit BGP routes
received across the different mechanisms to be able to tie-break in a
single RIB according to the properties of the routes within that RIB.
The choice of the mapping mechanism would likely be based on the
desired overall deployment model for routes with color and the
underlying comparability of the routes as they are distributed across
the cooperating networks.
The chosen RIB on that BGP Speaker would then be used to create the
route resolution state for BGP routes with color for that device.
9. IANA Considerations
IANA is requested to allocate a Route Distinguisher from the Route
Distinguisher Type Field registry from the IETF Review range. The
Description should be "RD-Color, Administrator field is a four-byte
Color, Assigned value field is a two-byte integer". The reference
should be this document.
IANA is requested to allocate a BGP Extended Community from the
Transitive Opaque Extended Community Sub-Types registry. Its name
will be "Classful Transport Original RD". The reference should be
this document.
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IANA is requested to allocate a BGP Extended Community from the
Transport Class Extended Communities Sub-Types registry. Its Name
will be "Classful Transport Original RD". The reference should be
this document.
10. Security Considerations
The BGP transport route use cases for "BGP routes with color" largely
overlap those for the original BGP Labeled Unicast protocol
extension. ([RFC8277]) Such routes are traditionally only accepted
from trusted BGP Speakers that exist within a BGP transport domain.
This document defines procedures for BGP Speakers implementing both
the BGP-CAR and BGP-CT address families to mutually exchange routing
information. Some of these procedures utilize BGP Extended
Communities. Care should be taken to not accept routes with Extended
Communities with mapping semantics from parties not eligible to
participate in these procedures. Such care may include filtering, or
discarding reachability with such Extened Communities from
unauthorized parties.
11. References
11.1. Normative References
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8277] Rosen, E., "Using BGP to Bind MPLS Labels to Address
Prefixes", RFC 8277, DOI 10.17487/RFC8277, October 2017,
<https://www.rfc-editor.org/info/rfc8277>.
[RFC8669] Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah,
A., and H. Gredler, "Segment Routing Prefix Segment
Identifier Extensions for BGP", RFC 8669,
DOI 10.17487/RFC8669, December 2019,
<https://www.rfc-editor.org/info/rfc8669>.
[RFC9252] Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene,
B., Zhuang, S., and J. Rabadan, "BGP Overlay Services
Based on Segment Routing over IPv6 (SRv6)", RFC 9252,
DOI 10.17487/RFC9252, July 2022,
<https://www.rfc-editor.org/info/rfc9252>.
[I-D.dskc-bess-bgp-car]
Rao, D., Agrawal, S., Filsfils, C., Steinberg, D., Jalil,
L., Su, Y., Decraene, B., Guichard, J., Talaulikar, K.,
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Patel, K., Wang, H., and J. Uttaro, "BGP Color-Aware
Routing (CAR)", Work in Progress, Internet-Draft, draft-
dskc-bess-bgp-car-05, 6 July 2022,
<https://www.ietf.org/archive/id/draft-dskc-bess-bgp-car-
05.txt>.
[I-D.kaliraj-idr-bgp-classful-transport-planes]
Vairavakkalai, K., Venkataraman, N., Rajagopalan, B.,
Mishra, G., Khaddam, M., Xu, X., Szarecki, R. J., Gowda,
D. J., Yadlapalli, C., and I. Means, "BGP Classful
Transport Planes", Work in Progress, Internet-Draft,
draft-kaliraj-idr-bgp-classful-transport-planes-17, 30
June 2022, <https://www.ietf.org/archive/id/draft-kaliraj-
idr-bgp-classful-transport-planes-17.txt>.
11.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <https://www.rfc-editor.org/info/rfc4360>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
Appendix A. Acknowledgements
TBD
Appendix B. Contributors
TBD
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Appendix C. Example NLRI Mapping
C.1. Mapping a BGP-CT route into BGP-CAR
Input:
* Route Distinguisher 192.0.2.1:100
* Endpoint: 10.0.0.1/32
* Label: 100
* Color: 999
BGP-CT state:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Label |Rsrv |S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Route Distinguisher (8 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4/IPv6 Prefix ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BGP-CT NLRI (AFI=1, SAFI=76)
Length: 0x98 (152 bits)
Label: 0x00 0x00 0x64 (100)
Rsrv: 0x00 (0)
S: 0x01 (1)
Route Distinguisher: 0x00 0x01 0xc0 0x00 0x02 0x01 0x00 0x64
(Type 1, 192.0.2.1 : 100)
IPv4/IPv6 Prefix: 0x20 0x0a 0x00 0x00 0x01 (32 / 10.0.0.1)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0xa | SubType= 0x02 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Class ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Transport Class Extended Community:
Type: 0x0a
SubType: 0x02
Reserved: 0x00 0x00
Transport Class ID: 0x00 0x00 0x03 0xe7 (999)
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Output:
* NLRI Type: 1
* Prefix Length: 32
* IP Prefix: 10.0.0.1
* Color: 999
* Label TLV:
- Type: 1
- Length: 3
- Value: 100
* CTOI Extended Community: 999
* CTORD Extended Community: 192.0.2.1:100
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Length | Key Length | NLRI Type |Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
CAR NLRI (AFI=1, SAFI=83):
NLRI Length: 0x10 (16 octets)
Key Length: 0x09 (9 octets)
NLRI Type: 0x01 (Color-Aware Routes NLRI Type)
Prefix Length: 0x20 (32)
IP Prefix: 0x0a 0x00 0x00 0x01 (10.0.0.1)
Color: 0x00 0x00 0x03 0xe7 (999)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Label TLV:
Type: 0x01 (Label TLV)
Length: 0x03 (3)
Label: 0x00 0x00 0x64 (100)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0x0a | SubType= TBD | RESERVED (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Transport Class ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Classful Transport Original Intent Extended Community:
Type: 0x0a
SubType: TBD
RESERVED: 0x00 0x000
Transport Class ID: 0x00 0x00 0x03 0xe7 (999)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0x03 | SubType= TBD | Value (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value continued |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Classful Transport Original RD Extended Community:
Type: 0x03
SubType: TBD
Value: 0x00 0x01 0xc0 0x00 0x02 0x01 0x00 0x64
(Type 1, 192.0.2.1 : 100)
C.2. Mapping a BGP-CAR route into BGP-CT
Input:
* NLRI Type: 1
* Prefix Length: 32
* IP Prefix: 10.0.0.1
* Color: 999
* Label TLV:
- Type: 1
- Length: 3
- Value: 100
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Length | Key Length | NLRI Type |Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
CAR NLRI (AFI=1, SAFI=83):
NLRI Length: 0x10 (16 octets)
Key Length: 0x09 (9 octets)
NLRI Type: 0x01 (Color-Aware Routes NLRI Type)
Prefix Length: 0x20 (32)
IP Prefix: 0x0a 0x00 0x00 0x01 (10.0.0.1)
Color: 0x00 0x00 0x03 0xe7 (999)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Label TLV:
Type: 0x01 (Label TLV)
Length: 0x03 (3)
Label: 0x00 0x00 0x64 (100)
Output:
* Route Distinguisher 192.0.2.1:100
* Endpoint: 10.0.0.1/32
* Label: 100
* Color: 999
BGP-CT state:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Label |Rsrv |S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Route Distinguisher (8 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4/IPv6 Prefix ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BGP-CT NLRI (AFI=1, SAFI=76)
Length: 0x98 (152 bits)
Label: 0x00 0x00 0x64 (100)
Rsrv: 0x00 (0)
S: 0x01 (1)
Route Distinguisher: 0xTBD 0xTBD 0x00 0x00 0x03 0xe7 0x00 0x00
(Type TBD - RD-Color, 999:0)
IPv4/IPv6 Prefix: 0x20 0x0a 0x00 0x00 0x01 (32 / 10.0.0.1)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= 0xa | SubType= 0x02 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Class ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Transport Class Extended Community:
Type: 0x0a
SubType: 0x02
Reserved: 0x00 0x00
Transport Class ID: 0x00 0x00 0x03 0xe7 (999)
Author's Address
Jeffrey Haas
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
United States of America
Email: jhaas@juniper.net
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