BGP MVPN in IPv6 Infrastructure Networks: Problems and Solution Approaches
draft-duan-bess-mvpn-ipv6-infras-01
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| Authors | Fanghong Duan , Jingrong Xie | ||
| Last updated | 2022-05-20 | ||
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draft-duan-bess-mvpn-ipv6-infras-01
Network Working Group F. Duan
Internet-Draft J. Xie
Updates: 6514 (if approved) Huawei Technologies
Intended status: Standards Track 20 May 2022
Expires: 21 November 2022
BGP MVPN in IPv6 Infrastructure Networks: Problems and Solution
Approaches
draft-duan-bess-mvpn-ipv6-infras-01
Abstract
MVPN deployment faces some problems while used in provider's IPv6
infrastructure networks. This document describes these problems, and
the solutions to solve these problems.
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.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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 21 November 2022.
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
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Problems and Solutions . . . . . . . . . . . . . . . . . . . 2
3.1. Problems . . . . . . . . . . . . . . . . . . . . . . . . 2
3.2. Modification of C-Multicast route NLRI . . . . . . . . . 4
3.3. Route reflection control . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
BGP MVPN procedure is defined in [RFC6514]. As a mature MVPN
technology, it has been accepted by most operators and vendors. In
[RFC6515], BGP MVPN is updated for IPv6 infrastructure networks.
However, the deployment of BGP MVPN in IPv6 network still faces some
problems. This document describes these problems, and the solutions
to solve these problems.
2. Terminology
Readers of this document are assumed to be familiar with the
terminology and concepts of the documents listed as Normative
References.
3. Problems and Solutions
3.1. Problems
In [RFC6514], the following processes are not suitable if IPv6
infrastructure addresses are used in provider's networks:
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1. In paragraph 7 of section 11.1.3, it described that "To support
non-segmented inter-AS tunnels, the Source AS field in the
C-multicast route is set to value of the Originating Router's IP
Address field of the found Intra-AS I-PMSI A-D route". In NLRI
of C-multicast route, Source AS field is 4 bytes length, while
the Originating Router's IP Address field of Intra-AS I-PMSI A-D
route is 16 bytes length in provider's IPv6 networks.
2. In paragraph 2 of section 11.2, it described that "To support
non-segmented inter-AS tunnels, instead of matching the RD and
Source AS carried in the C-multicast route against the RD and
Source AS of an Inter-AS I-PMSI A-D route, the ASBR should match
it against the RD and the Originating Router's IP Address of the
Intra-AS I-PMSI A-D routes". Source AS field in NLRI of
C-multicast route cannot be translated to the Originating
Router's IP Address of the Intra-AS I-PMSI A-D routes in
provider's IPv6 networks, because of the mismatch of their field
length.
In [RFC7716], zero RD is introduced in BGP MVPN NLRIs to enable
Global Table Multicast service in provider's networks. In IPv6
infrastructure networks, Leaf PEs cannot send two distinct
C-multicast route to two individual upstream root PEs for selctive
forwarding, because the RD of the two roots is the same.
In the process of evolution to IPv6, IPv4 and IPv6 infrastructure
addresses will coexist in the provider's network. The following
figure is an example of BGP MVPN evolution to IPv6.
+-----------+ +---+ +---+ +-----------+
| +-------+ | | | | | | +-------+ |
| | O-MVRF| |=BGP Peer4=| | | |=BGP Peer4=| | O-MVRF| |
| +-------+ | | | | | | +-------+ |
| | | | | | | |
| PE1 | |RR1| ... |RRn| | PE2 |
| | | | | | | |
| +-------+ | | | | | | +-------+ |
| | N-MVRF| |=BGP Peer6=| | | |=BGP Peer6=| | N-MVRF| |
| +-------+ | | | | | | +-------+ |
+-----------+ +---+ +---+ +-----------+
O-MVRF = Old Multicast VRF using IPv4 infrastructure addresses
N-MVRF = New Multicast VRF using IPv6 infrastructure addresses
Figure 1: BGP MVPN Evolution to IPv6 Infrastructure
During the evolution process, IPv4 and IPv6 parallel BGP sessions are
established between Provider Edge routers and Reflector routers, if
the BGP MVPN route send to all IPv4 and IPv6 BGP peer without any
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control, the number of the PATHs of these routes will be doubled with
each reflection while BGP ADD-PATH [RFC7911] procedure is enabled on
Reflector routers.
3.2. Modification of C-Multicast route NLRI
To support non-segmented inter-AS tunnels in IPv6 infrastructure
network, the C-Multicast route NLRI is redefined as following:
+-----------------------------------+
| RD (8 octets) |
+-----------------------------------+
| Root Distinguisher (4 octets) |
+-----------------------------------+
| Multicast Source Length (1 octet) |
+-----------------------------------+
| Multicast Source (variable) |
+-----------------------------------+
| Multicast Group Length (1 octet) |
+-----------------------------------+
| Multicast Group (variable) |
+-----------------------------------+
In the above figure, the Root Distinguisher field replaces the Source
As field defined in [RFC6514]. When constructing a C-Multicast
route, leaf PE follows the following specification:
1. If the Originating Router's IP Address field of the found Intra-
AS I-PMSI A-D route is an IPv4 address, the Root Distinguisher
field MUST be treated as Source AS field and section 11.1.3 of
[RFC6514] MUST be followed.
2. If the Originating Router's IP Address field of the found Intra-
AS I-PMSI A-D route is an IPv6 address and the root PE and leaf
PE are in the same AS, the Root Distinguisher field MUST be
treated as Source AS field and section 11.1.3 of [RFC6514] MUST
be followed.
3. If the Originating Router's IP Address field of the found Intra-
AS I-PMSI A-D route is an IPv6 address and the root PE and leaf
PE are in the different ASs, a four bytes distinct value MUST be
assigned by leaf PE for each root PE, the Root Distinguisher
field in C-Multicast NLRI is filled with this value and a
distinct C-multicast route will be send to individual upstream
root PE.
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When receiving a C-Multicast route from E-BGP neighbors, the ASBR
checks whether an IPv6 VRF Route Import Extended Community is
included in this route and takes following actions:
1. If the IPv6 VRF Route Import Extended Community does not exist in
the C-Multicast route, the ASBR treats the Root Distinguisher
field as Source AS field and follows the description in section
11.2 of [RFC6514].
2. If the IPv6 VRF Route Import Extended Community does exist in the
C-Multicast route, the ASBR match the IPv6 address carried in
this extended community and the RD in C-Multicast route NLRI
against the Originating Router's IP Address and the RD of the
Intra-AS I-PMSI A-D routes. If the corresponding Intra-AS I-PMSI
A-D route exists, the ASBR propagates the C-Multicast route in
its local AS.
3.3. Route reflection control
To reduce BGP MVPN routes in Parallel IPv4 and IPv6 BGP sessions
scenario, the following actions should be taken by sender PEs:
1. For Intra-AS I-PMSI A-D Route, S-PMSI A-D Route and Leaf A-D
Route, if the Originating Router's IP Address field in the route
is filled with an IPv6 address, it is sent to the IPv6 BGP
neighbors; otherwise, it is sent to the IPv4 BGP neighbors.
2. For Inter-AS I-PMSI A-D Route and Source Active A-D Route, it is
sent to both IPv6 BGP neighbors and IPv4 BGP neighbors.
3. For C-Multicast Route, if the IPv6 VRF Route Import Extended
Community exists in the route, it is sent to the IPv6 BGP
neighbors; otherwise, it is sent to the IPv4 BGP neighbors.
In the reflector routers, the part of routes which are received from
IPv6 BGP neighbors will be reflected to other IPv6 BGP neighbors and
the other part of routes which are received from IPv4 BGP neighbors
will be reflected to other IPv4 BGP neighbors.
4. Security Considerations
This document introduces no new security considerations beyond those
already specified in [RFC6514] and [RFC6515].
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5. IANA Considerations
This document contains no actions for IANA.
6. Acknowledgements
Your name here
7. Normative 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>.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
<https://www.rfc-editor.org/info/rfc6514>.
[RFC6515] Aggarwal, R. and E. Rosen, "IPv4 and IPv6 Infrastructure
Addresses in BGP Updates for Multicast VPN", RFC 6515,
DOI 10.17487/RFC6515, February 2012,
<https://www.rfc-editor.org/info/rfc6515>.
[RFC7716] Zhang, J., Giuliano, L., Rosen, E., Ed., Subramanian, K.,
and D. Pacella, "Global Table Multicast with BGP Multicast
VPN (BGP-MVPN) Procedures", RFC 7716,
DOI 10.17487/RFC7716, December 2015,
<https://www.rfc-editor.org/info/rfc7716>.
[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>.
[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>.
Authors' Addresses
Fanghong Duan
Huawei Technologies
Email: duanfanghong@huawei.com
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Jingrong Xie
Huawei Technologies
Email: xiejingrong@huawei.com
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