Color Operation with BGP Label Unicast
draft-chan-idr-bgp-lu2-00
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| Author | Louis Chan | ||
| Last updated | 2019-11-03 | ||
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draft-chan-idr-bgp-lu2-00
IDR Working Group Louis Chan
INTERNET-DRAFT
Intended status: Experimental Juniper Networks
Expires: May 4, 2020 Nov 4, 2019
Color Operation with BGP Label Unicast
draft-chan-idr-bgp-lu2-00.txt
Abstract
This document specifies how to carry colored path advertisement via an enhancement
to the existing protocol BGP Label Unicast. It would allow backward compatibility
with RFC8277.
The targeted solution is to use stack of labels advertised via BGP Label Unicast
2.0 for end to end traffic steering across multiple IGP domains. The operation is
similar to Segment Routing.
This proposed protocol will convey the necessary reachability information to the
ingress PE node to construct an end to end path
Status of this Memo
This Internet-Draft is submitted in full conformance with the provisions of BCP 78
and BCP 79.
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than as "work in progress."
This Internet-Draft will expire on May 4, 2020.
Copyright Notice
Copyright (c) 2017 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
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Table of Contents
1. Introduction................................................................2
2. Conventions used in this document...........................................3
3. Carrying Label Mapping Information with Color and Label Stack...............3
3.1. Color extended community for BGP Labeled Unicast.......................3
3.2. Color extended community for service prefixes..........................4
4. Uniqueness of path entries..................................................4
5. AIGP consideration..........................................................4
6. Explicit Withdraw of a <color, prefix>......................................4
7. Error Handling Procedure....................................................5
8. Security Considerations.....................................................5
9. IANA Considerations.........................................................5
10. References.................................................................5
10.1. Normative References.................................................5
10.2. Informative References...............................................5
11. Acknowledgments............................................................6
1. Introduction
The proposed protocol is aimed to solve interdomain traffic steering, with
different transport services in mind. One application is low latency service across
multiple IGP domains, which could scale up to 100k routers network.
BGP is a flexible protocol. With additional of color attribute to BGP Label
Unicast, a path with specific color would be given a meaning in application - a low
latency path, a fully protected path, or a path for diversity.
The stack of labels would mean an end to end path across domains through each ABR
or ASBR. Each ABR or ASBR will take one label from the stack, and hence pick the
forwarding path to next ABR, ASBR, or the final destination.
And the label in the stack may be derived from any of the below
- Prefix SID
- Binding SID for RSVP LSP
- Binding SID for SR-TE LSP
- Local assigned label
The enhancement to the original RFC8277 is to add color extended community, with
multiple advertisement allowed. The result is similar to multi-topology BGP-LU with
different colors.
A new [BGP-CAP] should be required to enable such slicing.
On the other hand, to enable the service prefixes to be mapped according, the
L3VPN, L2VPN, EVPN and prefix with BGP signaling, the color extended community is
also added there. In the PE node, the service prefixes with color will be matched
to a transport tunnel with the same color.
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The following is an example
PE1----ABR1-----ABR2-----PE2
PE1 will send the following labels with a color 100 path
[2001 13001 801 16], where
2001 - SR label to reach ABR1
13001 - Binding-SID label to reach ABR2. Underlying tunnel type is RSVP-TE
801 - Binding-SID label to reach PE2. Underlying tunnel type is SR-TE
16 - a VPN label
If PE1 wants to reach PE2 with another colored path, say color 200, the label stack
could be different.
2. Conventions used in this document
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 RFC 2119 [RFC2119].
In this document, these words will appear with that interpretation only when in
ALL CAPS. Lower case uses of these words are not to be interpreted as carrying
significance described in RFC 2119.
3. Carrying Label Mapping Information with Color and Label Stack
3.1. Color extended community for BGP Labeled Unicast
The addition of Color Extended Community is an opaque extended community from
RFC4360 and RFC5512. The draft allows multiple color values advertisement.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x03 | 0x0b |C|O| Reserved |X|X|X|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ 0x03 | 0x0b |C|O| Reserved |X|X|X|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Color value advertisement format
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Both in BGP update and MP_UNREACH_NLRI message, multiple color extended communities
could be included. It means that multiple colors, indicating different kind of
services, could share the same label stack.
If only one color extended community is specified, only prefix with that color
value is updated or withdrawn.
If a MP_UNREACH_NLRI message without any color specified is received for a given
prefix, that prefix with any color should not be affected.
If color extended community is not present in a BGP update message, it would be
treated as normal BGP-LU without any color.
3 bits of XXX is reserved here for the draft.
Color value 0 is reserved for future interoperability purpose.
3.2. Color extended community for service prefixes
The same format of color extended community is advertised with service prefixes.
The order of the color extended community could be interpreted as
- Order of primary and fallback colors
- Or, ECMP of equal split between color tunnels
The above would be interpreted by the receiving PE upon its local configuration.
4. Uniqueness of path entries
Use of color can be considered to slice into multiple BGP Label Unicast RIB.
Therefore, it should be treated as unique entries for the <color, prefix>.
e.g. <color, prefix>, [labels]
<1, 10.1.1.1/32>, [100 200]
<2, 10.1.1.1/32>, [100 200]
<null, 10.1.1.1/32>, [100 200]
All these 3 NLRI are considered different but valid entries for different color
instances.
5. AIGP consideration
AIGP (RFC7311) would be also used in here to embed certain metric across.
6. Explicit Withdraw of a <color, prefix>
According to RFC8277, MP_UNREACH_NLRI can be used to remove binding of a <color,
prefix>.
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Compatibility is set to 0xC00000 to specify the use of color. Multiple color
extended communities could be applied here.
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 | Compatibility |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix ~
~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NLRI for Withdrawal
7. Error Handling Procedure
If BGP receiver could not handle the NLRI, it should silently discard with error
logging.
8. Security Considerations
9. IANA Considerations
TBD. It will require a new BGP capability code to enable such color operation.
New SAFI might be required as well.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels",
BCP 14, RFC 2119, March 1997.
10.2. Informative References
[RFC3107] Rekhter, Y. and E. Rosen, "Carrying Label Information in BGP-4", RFC
3107, DOI 10.17487/RFC3107, May 2001,
<https://www.rfc-editor.org/info/rfc3107>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006
<https://www.rfc-editor.org/info/rfc4360>.
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[RFC5512] Mohapatra, P. and E. Rosen, "The BGP Encapsulation Subsequent Address
Family Identifier (SAFI) and the BGP Tunnel Encapsulation Attribute", RFC
5512, April 2009.
<https://www.rfc-editor.org/info/rfc5512>.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., and D.
McPherson, "Dissemination of Flow Specification Rules", RFC 5575, DOI
10.17487/RFC5575, August 2009,
<http://www.rfc-editor.org/info/rfc5575>.
[RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, "Advertisement of
Multiple Paths in BGP", RFC 7911, DOI 10.17487/RFC7911, July 2016,
<https://www.rfc-editor.org/info/rfc7911>.
[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>.
[BGP-CAP] Chandra, R. and J. Scudder, "Capabilities Advertisement
with BGP-4", RFC 2842, May 2000.
11. Acknowledgments
The following people have contributed to this document:
Jeff Haas, Juniper Networks
Shraddha Hedge, Juniper Networks
Santosh Kolenchery, Juniper Networks
Shihari Sangli, Juniper Networks
Krzysztof Szarkowicz, Juniper Networks
Yimin Shen, Juniper Networks
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Authors Addresses
Louis Chan (editor)
Juniper Networks
2604, Cityplaza One, 1111 King's Road
Taikoo Shing
Hong Kong
Phone: +85225876659
Email: louisc@juniper.net
Chan Expires May 4, 2020 [Page 7]