Internet DRAFT - draft-geng-bier-ipv6-inter-domain
draft-geng-bier-ipv6-inter-domain
Network Working Group L. Geng
Internet-Draft China Mobile
Intended status: Standards Track J. Xie
Expires: April 30, 2021 Huawei Technologies
M. McBride
Futurewei
G. Yan
X. Geng
Huawei Technologies
October 27, 2020
Inter-Domain Multicast Deployment using BIERv6
draft-geng-bier-ipv6-inter-domain-02
Abstract
Bit Index Explicit Replication IPv6 encapsulation (BIERv6) introduces
an approach to use IPv6 extension header to carry BIER header with
IPv6 unicast address as destination address. It provides the ability
to replicate a packet from one router to other routers in a different
domain as well as routers in the same domain. This document
introduces the techniques for multicast deployment across multiple
domains using BIERv6, and demonstrate how BIERv6 is beneficial for
such deployment.
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] and
[RFC8174].
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."
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This Internet-Draft will expire on April 30, 2021.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Inter-domain Multicast Overview . . . . . . . . . . . . . . . 3
4. Inter-domain Multicast Deployment using BIERv6 . . . . . . . 4
4.1. Hierarchical Multicast . . . . . . . . . . . . . . . . . 4
4.2. Peering Multicast . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Bit Index Explicit Replication [RFC8296] IPv6 encapsulation (BIERv6)
described in [I-D.xie-bier-ipv6-encapsulation] introduces an approach
to use IPv6 extension header to carry BIER header. One BIERv6
option, using IPv6 unicast address as destination address provides
the ability to replicate a packet from one router to other routers in
a different domain as well as routers in the same domain. This
document introduces the techniques for multicast deployment across
multiple domains using BIERv6, and demonstrates how BIERv6 is
beneficial for such deployment.
The word "domain" used in this document means a closely connected set
of nodes or simply "IGP domain" or "autonomous system (AS)". The
word "inter-domain" used in this document means interconnected IGP
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domains or autonomous systems (ASes) belonging to a single "BIERv6
domain" as defined in [I-D.xie-bier-ipv6-encapsulation].
There is no concept of MVPN segmentation [RFC6513] in this document.
Instead, It is a non-segmented MVPN or inter-domain stateless
multicast deployment in this document, and a single BIER Sub-domain
throughout the "inter-domain" scope of the BIERv6 domain is assumed.
2. Terminology
Readers of this document are assumed to be familiar with the
terminology and concepts of the documents listed as Normative
References.
3. Inter-domain Multicast Overview
It is common to deploy multicast services across multiple domains.
One typical scenario for this type of deployment is in a service-
provider network for MVPN service as described in
[I-D.ietf-bier-ipv6-requirements]. Service provider network tends to
be very heterogeneous with full-mesh backbone network, and metro
networks with fabric for dense area coverage or ring-shaped for
sparse area coverage. The backbone network and metro networks are
autonomous systems interconnected by border routers (BRs).
Multicast-based delivery of video need to be set up from a source
router on the backbone to each of the boundary routers of each metro
network.
This scenario may have some variant. For example, multicast source
router is a Top of Rack (TOR) switch in a service provider data
center(SPDC) connected to backbone with data center gateway(s) (DC-
GW), and multicast receiver is the home broadband subscribers
connected to boundary routers (e.g. BNG) of each metro network.
Operators may want to set up multicast-based delivery from TOR to
BNGs seamlessly without segmentation or stitching on DC-GW(s) or
BR(s).
It is described as hierachical multicast in this document.
Another typical scenario for inter-domain multicast deployment is in
peering network as described in [RFC8313] to set up multicast-based
delivery of content across inter-domain peering points.
This scenario may have some variant. For example, interconnected
content delivery networks (CDNs) (described in [RFC6770]) owned by
Network Service Providers (NSPs) or Enterprise Service Providers may
need to deliver multicast from one to others.
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It is described as peering multicast in this document.
4. Inter-domain Multicast Deployment using BIERv6
4.1. Hierarchical Multicast
Following is an example of hierarchical deployment of multicast.
+---------------------+
| Metro 2 (AS 65002) |
| +-----+ +------+ |
+-------| BR2 | | PE2x |---RCV
/ | +-----+ +------+ |
/ +---------------------+
+---------------------+ / Bfr-id 1 to 256
| Backbone (AS 65001) | /
| +------+ +-----+ /
SRC---| PE1x | | BR1 | |
| +------+ +-----+ \
+---------------------+ \ Bfr-id 257 to 512
| \ +---------------------+
| \ | Metro 3 (AS 65003) |
| \ | +-----+ +------+ |
| +-------| BR3 | | PE3x |---RCV
| | +-----+ +------+ |
| +---------------------+
| |
|<----------------- BIERv6 Domain --------------->|
BR = Border Router
SRC = Multicast Source
RCV = Multicast Receiver
Figure 1: Inter-Domain Hierarchical Multicast
Multicast source is connected to PE1x, and multicast receivers are
connected to PE2x and PE3x.
PE1x, PE2x, PE3x is located in Backbone (AS 65001), Metro 2 (AS
65002), and Metro 3 (AS 65003) respectively, and BR1, BR2, BR3 is
boarder of these three domains. They belong to a single
administrative domain.
IGP underlay for BIERv6 is deployed in Metro2, Metro3 respectively.
The bfr-ids in Metro2 and Metro 3 should be divided rationally.
PE1x, PE2x, PE3x uses 2001:DB8::E1, 2001:DB8::E2, 2001:DB8::E3 as
End.BIER IPv6 address respectively.
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BR1, BR2, BR3 uses 2001:DB8::B1, 2001:DB8::B2, 2001:DB8::B3 as
End.BIER IPv6 address respectively.
All of them use the Non-MPLS static BSL-SD-SI BIFT encoding method
described in [I-D.ietf-bier-non-mpls-bift-encoding] as the auto-
generation method.
On BR1, static configuration can be used to construct inter-domain
BIERv6 forwarding table.
bier sub-domain 6 ipv6-underlay
bfr-prefix interface loopback0
end-bier 2001:DB8::B1
encapsulation ipv6 bsl 256 max-si 2
static-bift
nexthop end-bier 2001:DB8::B2 bfr-id 1 to 256
nexthop end-bier 2001:DB8::B3 bfr-id 257 to 512
Accordingly, the following BIFTs will be constructed:
BIFT correspond to SD<6>/BSL<256>/SI<0>
(neighbor = 2001:DB8::B2, F-BM = ffff....ffff)
BIFT correspond to SD<6>/BSL<256>/SI<1>
(neighbor = 2001:DB8::B3, F-BM = ffff....ffff)
On PE1x, static configuration can be used to construct inter-domain
BIERv6 forwarding table. Note that PE1x doesn't need to assign a
valid BFR-id uniquely among many.
bier sub-domain 6 ipv6-underlay
bfr-prefix interface loopback0
end-bier 2001:DB8::E1
encapsulation ipv6 bsl 256 max-si 2
static-bift
nexthop end-bier 2001:DB8::B1 bfr-id 1 to 512
Accordingly, the following BIFTs will be constructed:
BIFT correspond to SD<6>/BSL<256>/SI<0>
(neighbor = 2001:DB8::B1, F-BM = ffff....ffff)
BIFT correspond to SD<6>/BSL<256>/SI<1>
(neighbor = 2001:DB8::B1, F-BM = ffff....ffff)
Use of BGP as inter-domain underlay protocol to advertise the BIER
information from BR2 or BR2 to BR1, or from BR1 to PE1x is outside
the scope of this document.
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On each domain, two redundant border routers may be deployed, and
anycase IPv6 address can be used on each pair of BRs as End.BIER IPv6
address.
Inter-Domain BIER will converge normally when unicast converge and
the BIFT will be reconstructed accordingly.
For multicast overlay layer, there are no extensions needed. MVPN is
deployed on PE1x, PE2x and PE3x using sub-domain 6 and bsl 256
without segmentation on border router(s).
Note: Use of the IPv6 address configured on PE1 to identify an MVPN
instance can eliminate the need for BFR-id configuration on PE1x,
which otherwise has to be configured from the space of a sub-domain.
4.2. Peering Multicast
Following is an example of peering deployment of multicast.
+---------------------+
| AD-2 (AS 65002) |
+---+ | +-----+ +------+ |
/ I \ | | BR2 | | PE2x |---RCV
(color 1) ( N ) | +-----+ +------+ |
Bfr-id 1 to 256 ( T ) +---------------------+
+---------------------+ ( E ) Bfr-id 1 to 512
| AD-1 (AS 65001) | ( R ) (color 2)
| +------+ +-----+ | ( C )
SRC---| PE1x | | BR1 | | ( O )
| +------+ +-----+ | ( N )
| +------+ | ( N )
RCV---| PE1y | | ( E )
| +------+ | ( C ) (color 3)
+---------------------+ ( T ) Bfr-id 1 to 256
( I ) +---------------------+
( O ) | AD-3 (AS 65003) |
\ N / | +-----+ +------+ |
+---+ | | BR3 | | PE3x |---RCV
| +-----+ +------+ |
+---------------------+
AD = Administrative Domain (independent autonomous system)
BR = Border Router
SRC = Multicast Source
RCV = Multicast Receiver
Figure 2: Inter-Domain Peering Multicast
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Each Administrative Domain AD-1, AD-2 or AD-3 is configured a unique
color. Color 1, 2, 3 are used in this example.
For routing underlay layer, the ingress router uses IGP protocol (IS-
IS as example in this document) for the domain it belongs to, and
uses static configuration for the domain it doesn't belong to.
Below is an example of routing underlay configuration on PE1x. Note
that PE1x doesn't need to assign a valid BFR-id per color.
# PE1x routing underlay layer configuration
bier sub-domain 6 ipv6-underlay
bfr-prefix interface loopback0
end-bier 2001:DB8::E1
encapsulation ipv6 bsl 256 max-si 1
color 1 protocol isis
color 2 static-bift
nexthop end-bier 2001:DB8::B2 bfr-id 1 to 512
color 3 static-bift
nexthop end-bier 2001:DB8::B3 bfr-id 1 to 256
The following lists the BIFT that will be constructed on PE1x:
BIFT corresponding to SD<6>/BSL<256>/SI<0> for color 1 ;;Ref1
BIFT corresponding to SD<6>/BSL<256>/SI<0> for color 2 ;;Ref2
BIFT corresponding to SD<6>/BSL<256>/SI<1> for color 2 ;;Ref3
BIFT corresponding to SD<6>/BSL<256>/SI<0> for color 3 ;;Ref4
Ref1: BIFT constructed using IGP.
Ref2: BIFT constructed using static configuration, with BR2 a multi-
hop BFR neighbor of PE1x.
Ref3: BIFT constructed using static configuration, with BR2 a multi-
hop BFR neighbor of PE1x.
Ref3: BIFT constructed using static configuration, with BR3 a multi-
hop BFR neighbor of PE1x.
For multicast overlay layer, the color extended community defined in
[RFC5512] is carried in Leaf A-D route together with the PTA
attribute.
(1) PE in each domain gets the color it belongs to. This can be done
by configuration on each PE in each domain.
(2) PE carries a color attribute in BGP-MVPN Leaf A-D route when
advertising to Ingress PE as response to explicit-tracking initiated
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by the Ingress PE. This can be done by configuration on MVPN
deployment. Refer to [I-D.xie-bier-ipv6-mvpn] for other attributes
needed to be used.
(3) The Ingress PE gets the Leaf A-D route, learns the BFERs of a
color (representing a domain) interested in a multicast flow, and
constructs the overlay forwarding table. Below is an example of the
overlay forwarding table on PE1x:
(VRF<X>, S<S1>, G<G1>)
(Color<1>, SD<6>, BSL<256>, SI<0>, BitString<0001>) ;;Ref1
(Color<2>, SD<6>, BSL<256>, SI<0>, BitString<0001>) ;;Ref2
(Color<2>, SD<6>, BSL<256>, SI<1>, BitString<0001>) ;;Ref3
(Color<3>, SD<6>, BSL<256>, SI<0>, BitString<0001>) ;;Ref4
Ref1: packet will be replicated according to the BitString<0001> and
the BIFT constructed using the IGP for SD<6>/BSL<256>/SI<0> for color
1.
Ref2: packet will be replicated according to the BitString<0001> and
the BIFT constructed using the static-bift configuration for
SD<6>/BSL<256>/SI<0> for color 2.
Ref3: packet will be replicated according to the BitString<0001> and
the BIFT constructed using the static-bift configuration for
SD<6>/BSL<256>/SI<1> for color 2.
Ref3: packet will be replicated according to the BitString<0001> and
the BIFT constructed using the static-bift configuration for
SD<6>/BSL<256>/SI<1> for color 3.
Note: BFR-id configuration on PE1x is only necessary when PE1x will
act as BFER, for example, there is multicast packet from PE2x to
PE1x. The BFR-ids in color 1, 2, 3 is independent on each other.
5. Security Considerations
Section 5.1 of [I-D.xie-bier-ipv6-encapsulation] should be strictly
deployed as a basic security mechanism for BIERv6 deployment.
In case the inter-domain "domains" are connected directly, for
example, they may be connected to the same physical infrastructure
(e.g., a Service Provider's network), then the "edge node" and
"external interface of each edge node" are both clear.
In case the inter-domain "domains" are connected remotely by a secure
connection, for example, they may be connected by a kind of VPN
connection, then the "external interface of each edge node" excludes
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the interface of the Customer Edge (CE) router connecting (through
VPN) to the Provider Edge(PE) router.
In case the inter-domain "domains" are connected remotely by an
insecure connection, for example, they may be connected by an
internet connection, then the "external interface of each edge node"
includes the interface of the Customer Edge (CE) router connecting
(through internet) to the Provider Edge(PE) router.
6. IANA Considerations
No IANA Allocation is required in this document.
7. Acknowledgements
TBD.
8. References
8.1. Normative References
[I-D.ietf-bier-ipv6-requirements]
McBride, M., Xie, J., Geng, X., Dhanaraj, S., Asati, R.,
Zhu, Y., Mishra, G., and Z. Zhang, "BIER IPv6
Requirements", draft-ietf-bier-ipv6-requirements-09 (work
in progress), September 2020.
[I-D.ietf-bier-non-mpls-bift-encoding]
Wijnands, I., Xu, X., and H. Bidgoli, "An Optional
Encoding of the BIFT-id Field in the non-MPLS BIER
Encapsulation", draft-ietf-bier-non-mpls-bift-encoding-02
(work in progress), August 2019.
[I-D.xie-bier-ipv6-encapsulation]
Xie, J., Geng, L., McBride, M., Asati, R., Dhanaraj, S.,
Zhu, Y., Qin, Z., Shin, M., Mishra, G., and X. Geng,
"Encapsulation for BIER in Non-MPLS IPv6 Networks", draft-
xie-bier-ipv6-encapsulation-08 (work in progress), July
2020.
[I-D.xie-bier-ipv6-mvpn]
Xie, J., McBride, M., Dhanaraj, S., Geng, L., and G.
Mishra, "Use of BIER IPv6 Encapsulation (BIERv6) for
Multicast VPN in IPv6 networks", draft-xie-bier-
ipv6-mvpn-03 (work in progress), October 2020.
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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,
DOI 10.17487/RFC5512, April 2009,
<https://www.rfc-editor.org/info/rfc5512>.
[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
2012, <https://www.rfc-editor.org/info/rfc6513>.
[RFC6770] Bertrand, G., Ed., Stephan, E., Burbridge, T., Eardley,
P., Ma, K., and G. Watson, "Use Cases for Content Delivery
Network Interconnection", RFC 6770, DOI 10.17487/RFC6770,
November 2012, <https://www.rfc-editor.org/info/rfc6770>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.
[RFC8313] Tarapore, P., Ed., Sayko, R., Shepherd, G., Eckert, T.,
Ed., and R. Krishnan, "Use of Multicast across Inter-
domain Peering Points", BCP 213, RFC 8313,
DOI 10.17487/RFC8313, January 2018,
<https://www.rfc-editor.org/info/rfc8313>.
8.2. 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>.
[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
Liang Geng
China Mobile
Beijing 10053
Email: gengliang@chinamobile.com
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Jingrong Xie
Huawei Technologies
Email: xiejingrong@huawei.com
Mike McBride
Futurewei
Email: mmcbride7@gmail.com
Gang Yan
Huawei Technologies
Email: yangang@huawei.com
Xuesong Geng
Huawei Technologies
Email: gengxuesong@huawei.com
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