Internet DRAFT - draft-xie-bier-ipv6-mvpn
draft-xie-bier-ipv6-mvpn
Network Working Group J. Xie
Internet-Draft Huawei Technologies
Intended status: Standards Track M. McBride
Expires: April 13, 2021 Futurewei
S. Dhanaraj
Huawei Technologies
L. Geng
China Mobile
G. Mishra
Verizon Inc.
October 10, 2020
Use of BIER IPv6 Encapsulation (BIERv6) for Multicast VPN in IPv6
networks
draft-xie-bier-ipv6-mvpn-03
Abstract
This draft defines the procedures and messages for using Bit Index
Explicit Replication (BIER) for Multicast VPN Services in IPv6
networks using the BIER IPv6 encapsulation. It provides a migration
path for Multicast VPN service using BIER MPLS encapsulation in MPLS
networks to multicast VPN service using BIER IPv6 encapsulation
(BIERv6) in IPv6 networks.
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 13, 2021.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use of PTA and Prefix-SID Attribute in x-PMSI A-D Routes . . 4
4. MVPN over BIERv6 Core . . . . . . . . . . . . . . . . . . . . 4
5. GTM over BIERv6 Core . . . . . . . . . . . . . . . . . . . . 6
6. Data Plane . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Encapsulation of Multicast Traffic . . . . . . . . . . . 7
6.2. MTU . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.3. TTL . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides optimal multicast forwarding without requiring
intermediate routers to maintain any per-flow state by using a
multicast-specific BIER header. BIERv6 refers to the deployment of
BIER in IPv6 networks using the BIER IPv6 encapsulation format
defined in [I-D.xie-bier-ipv6-encapsulation].
This document describes a method to realize MVPN services using BIER
as a P-tunnel in the IPv6 Networks (BIERv6 Networks). It defines a
method to use an IPv6 address, called Src.DTx in this document, as
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source address of an IPv6 header, to identify the MVPN instance at
the Egress PE. The Src.DTx address used as source address of a
BIERv6 packet represent both the context and the upstream-assigned
VPN Label in MVPN scenario defined in [RFC8556].
The Src.DTx address can be a normal IPv6 address of the BFR, for
example, a loopback address of the BFR. The Src.DTx address can also
be an IPv6 address allocated from an IPv6 address block, for example,
an IPv6 address allocated from an SRv6 locator if BIERv6 MVPN is
deployed in an SRv6 network.
In particular, MVPN deployment in IPv6 networks relies on L3VPN
deployment on IPv6 networks firstly, thus the c-multicast routing
procedure like Upstream Multicast Hop (UMH) Selection can be done.
As an example, the L3VPN deployment in SRv6 networks can be referred
to [I-D.ietf-bess-srv6-services].
Global Table Multicast (GTM) defined in [RFC7716] is also covered in
this document, as GTM shares the same BGP-MVPN signalling, while
providing an approach of Non-VPN multicast over a service provider
core with various P-tunnel type. For the same reason of UMH
selection as a base of GTM, the Global IPv4/IPv6 over SRv6 networks
can be referred to [I-D.ietf-bess-srv6-services].
2. Terminology
Readers of this document are assumed to be familiar with the
terminology and concepts of the documents listed as Normative
References. Additionally the following terms are used through out
the document.
o BIERv6 - BIER in IPv6 networks using the BIERv6 encapsulation
format defined in [I-D.xie-bier-ipv6-encapsulation].
o SRv6 - Segment Routing instantiated on the IPv6 dataplane as
defined in [I-D.ietf-spring-srv6-network-programming].
o SRv6 SID - SRv6 Segment Identifier as defined in
[I-D.ietf-spring-srv6-network-programming].
o End.DTx - Refers to the functions End.DT6, End.DT4, End.DT46
defined in [I-D.ietf-spring-srv6-network-programming].
o Src.DTx - Refers to the functions Src.DT4, Src.DT6, Src.DT46
defind in this document.
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o SRv6 L3 Service - L3VPN/Global-L3 service in SRv6 networks defined
in [I-D.ietf-bess-srv6-services], or MVPN/GTM service in BIERv6
networks defined in this document.
3. Use of PTA and Prefix-SID Attribute in x-PMSI A-D Routes
The BGP-MVPN I-PMSI A-D (Type 1) or S-PMSI A-D (Type 3) route (called
x-PMSI A-D route in this document), advertised by Ingress PE carries
the BIER (Type 11) PTA as specified in [RFC8556]. The BIER PTA
carried in the x-PMSI A-D route is used for explicitly tracking the
receiver-site PEs which are interested in a specific multicast flow.
It includes three BIER-specific fields, Sub-domain-id, BFR-id, and
BFR-prefix. For BIER P-tunnel using the BIERv6 encapsulation in IPv6
networks, the BFR-prefix field in the PTA MUST be set to the BFIR
IPv6 prefix and the MPLS Label field in the PTA MUST set to 0. For
MVPN over BIERv6, the Src.DTx IPv6 address of the BFIR is used to
identify the VRF instead of an MPLS Label. The Src.DTx IPv6 Address
(Src.DT6 or Src.DT4 or Src.DT46) MUST be carried within an SRv6 L3
Service TLV [I-D.ietf-bess-srv6-services] of BGP Prefix-SID attribute
in the x-PMSI A-D route.
The Ingress PE encapsulates the c-multicast IP packet with BIERv6
header and the source address in the outer IPv6 header will be set to
the Src.DTx IPv6 address advertised in the BGP-MVPN x-PMSI A-D
routes. See section 3 of [I-D.xie-bier-ipv6-encapsulation] for the
detailed packet format.
Egress PE (BFER) receiving the x-PMSI A-D routes with BIER PTA and
SRv6 L3 Service TLV learns the Src.DTx IPv6 address and uses it to
identify the VRF of the c-multicast packet.
When Egress PE receives a BIERv6 packet and the self bfr-id is set in
the bit-string field of the BIERv6 header, it retrieves the Src.DTx
IPv6 address from the source address of the IPv6 header to determine
the VRF and the Address Family (AF) of the c-multicast data packet,
and performs the MFIB lookup in the corresponding table.
4. MVPN over BIERv6 Core
[RFC8556] specifies the protocol and procedures to be followed by the
Ingress and Egress PEs to use BIER as a P-tunnel for MVPN in MPLS
networks. This section specifies the required changes and procedures
in addition to support BIER as a P-tunnel in IPv6 networks using
BIERv6.
In a IPv6 service provider network, many of the IP address fields
used in the BGP-MVPN routes are IPv6 address as specified in
[RFC6515]. These are listed below.
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o "Originating Router's IP Address" in the NLRI of Type 1, 3 or 4
BGP-MVPN route is an IPv6 address.
o "Network Address of Next Hop" field in the MP_REACH_NLRI attribute
is an IPv6 address.
o Route Targets Extended Community (EC) used in C-multicast join
(Type 6 or 7) route or Leaf A-D (Type 4) route is an IPv6 Address
Specific Extended Community, where the Global Administrator field
will be an IPv6 address identifies the Upstream PE or the UMH.
o "VRF Route Import Extended Community (EC)" carried by VPNv4 or
VPNv6 unicast routes (SAFI 128) or multicast routes (SAFI 129) is
an IPv6 Address Specific Extended Community.
On the Ingress PE (BFIR), the BGP-MVPN x-PMSI A-D route is
constructed as per the procedures specified in [RFC8556] and with the
following specifications.
o MPLS Label field in the BIER PTA MUST be set to Zero.
o BFR-prefix field in the BIER PTA MUST be set to the Ingress PEs
(BFIR) IPv6 BFR-Prefix Address. It does not need to be the same
as the other IPv6 address of the x-PMSI AD route.
o Route MUST also carry an BGP Prefix SID attribute with an SRv6 L3
Service TLV carrying an Src.DTx IPv6 address uniquely identifying
the MVPN instance.
If the MVPN is IPv4 MVPN, the Src.DTx can be either Src.DT4 or
Src.DT46. If the MVPN is IPv6 MVPN, the Src.DTx can be either
Src.DT6 or Src.DT46. The distribution of the x-PMSI A-D routes uses
the Src.DTx according to the local configuration, and is independent
to the use of End.DTx in VPN-IP unicast routes of this VPN. For
example, one can use End.DT46 for VPNv4 and VPNv6 unicast routes, but
use Src.DT4 for the MVPN routes for the same VPN. Another example,
one can use End.DX for VPNv4 unicast routes, but use Src.DT46 for the
MVPN routes for the same VPN.
BFIR MAY carry the BGP Prefix-SID attribute only in I-PMSI A-D route
when I-PMSI A-D route is used, while other S-PMSI A-D routes do not
carry the BGP Prefix-SID attribute.
BFIR MAY carry the BGP Prefix-SID attribute only in wildcard S-PMSI
A-D routes when the "S-PMSI Only" mode as described in [RFC6625] is
used, while other S-PMSI A-D routes do not carry the BGP Prefix-SID
attribute.
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On the Egress PE (BFER), the BGP-MVPN x-PMSI A-D route is processed
as per the procedures specified in [RFC8556] and with the following
specifications:
o The MPLS Label field in the BIER PTA of the BGP-MVPN x-PMSI A-D
route MUST be ignored and MUST not be used for the identification
of the VRF.
o The BGP-MVPN x-PMSI A-D route MUST be dropped if the BFR-prefix
field in the BIER PTA is not an IPv6 address.
o The BGP-MVPN x-PMSI A-D route MUST be dropped if it does not carry
a Src.DTx IPv6 address in the SRv6 L3 Service TLV in BGP Prefix
SID attribute.
o Leaf A-D route originated by the Egress PE (BFER) MUST carry the
BIER PTA with the BFR-prefix field set to the BFER IPv6 BFR-
prefix.
Valid BGP-MVPN x-PMSI A-D route received by an Egress PE (BFER) is
stored locally, and the Src.DTx IPv6 Address carried in the SRv6 L3
service TLV is used to identify the VRF of a c-multicast data packet.
This may be populated into forwarding table only when there is
c-multicast flow state with UMH of the specific BFIR this Src.DTx
located in.
If more than one x-PMSI A-D routes belonging to the same VRF has
different Src.DTx value, the processing is determined by the local
policy of the BFER.
If more than one x-PMSI A-D routes belonging to different VRF has the
same Src.DTx value, the BFER must log an error, and a BIERv6 packet
with this Src.DTx as the IPv6 source address MUST be dropped.
The BGP Prefix-SID attribute (which may include the Src.DTx in SRv6
L3 Service TLV) MUST NOT be carried in Leaf A-D route upon sending,
and MUST be ignored upon reception.
5. GTM over BIERv6 Core
As specified in [RFC7716], Global Table Multicast (GTM) uses the same
Subsequent Address Family Identifier (SAFI) value, the same Network
Layer Reachability Information (NLRI) format, and the same procedures
of MVPN with only a few adaptions. It support for both IPv4 and IPv6
multicast flows over either an IPv4 or IPv6 SP infrastructure. GTM
over BIERv6 core is obviously a case of IPv4/IPv6 multicast over an
IPv6 SP infrastructure with BIERv6 data-plane.
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The BIER (Type 11) PTA attribute and the BGP Prefix-SID attribute are
carried in the x-PMSI A-D route in GTM cases. When the a BGP-MVPN
x-PMSI A-D route is received by Egress PE, it is stored locally, and
the Src.DTx IPv6 Address of the Ingress PE in the route is used to
determine the VRF of a packet, which is the 'public' VRF in the case
of GTM.
There are some other attributes listed below for GTM over a BIERv6
core:
o Route Distinguishers - the RD field of a BGP-MVPN route's NLRI
MUST be set to zero (i.e., to 64 bits of zero) to represent a Non-
VPN GTM. See section 2.2 of [RFC7716].
o Route Targets Extended Community (EC) - The RT EC carried by the
BGP-MVPN C-multicast (Type 6 or 7) route or Leaf A-D (Type 4)
route MUST be an IPv6-address-specific Extended Community (EC).
The Global Administrator field identifies the Upstream PE or the
UMH, and the Local Administrator field MUST always be set to zero
in GTM case.
o VRF Route Import Extended Community (EC) - The VRF Route Import EC
carried by IPv4 or IPv6 routes (SAFI 1 or 4) or multicast routes
(SAFI 2) is an IPv6 Address Specific Extended Community.
GTM IPv4 multicast over an BIERv6 core may be considered an
alternative to support IPv4 IPTV content delivery during transition
to IPv6 period comparing to [RFC8114]. They both use IPv4-in-IPv6
encapsulation, while BIERv6 uses an additional BIER header within an
IPv6 Extension header to support stateless core.
6. Data Plane
6.1. Encapsulation of Multicast Traffic
BIER IPv6 encapsulation (BIERv6) [I-D.xie-bier-ipv6-encapsulation] is
used for forwarding the c-multicast traffic through an IPv6 core.
The following diagram shows the progression of an MVPN c-multicast
packet as it enters and leaves the intra-AS service-provider network.
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+---------------+ +---------------+
| P-IPv6 Header | | P-IPv6 Header |
| (SA=Src.DTx | | (SA=Src.DTx |
| DA=End.BIER) | | DA=End.BIER) |
+---------------+ +---------------+
| P-IPv6 ExtHdr | | P-IPv6 ExtHdr |
| (BIER header) | | (BIER header) |
++=========++ ++=============++ ++=============++ ++=========++
||C-IP Hdr || || C-IP Hdr || || C-IP Hdr || ||C-IP Hdr ||
++=========++ >> ++=============++ >> ++=============++ >> ++=========++
||C-Payload|| || C-Payload || || C-Payload || ||C-Payload||
++=========++ ++=============++ ++=============++ ++=========++
CE1-----------PE1------------------P2------------------PE2-----------CE2
Figure 1: BIERv6 MVPN/GTM Intra-AS
The Src.DTx SHOULD support as destination address of an ICMPv6
packet. If a loopback address of the BFR is used as Src.DTx address,
this is supported. If an address from an SRv6 locator is used as
Src.DTx address, the following pseudo-code describes how a packet
with Src.DTx as destination address is handled:
1. IF Last_NH = ICMPv6 ;;Ref1
2. Send to CPU.
3. ELSE
4. Drop the packet.
Ref1: ICMPv6 packet using Src.DT4, Src.DT6 or Src.DT46 as destination
address.
6.2. MTU
Each BFIR is expected to know the Maximum Transmission Unit (MTU) of
the BIER domain and the size of the BIERv6 encapsulation, thus each
BFIR can deduce the maximum size of the payload that can be
encapsulated in a BIERv6 packet. The section 3 of [RFC8296] applies.
6.3. TTL
The ingress PE (BFIR) should not copy the Time to Live (TTL) field
from the payload IP header received from a CE router to the delivery
IP header. Setting the TTL of the delivery IP header is determined
by the local policy of the ingress PE (BFIR) router per section 3 of
[RFC8296].
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7. Security Considerations
The security considerations defined in [RFC8556] and
[I-D.xie-bier-ipv6-encapsulation] apply equally to this document.
8. IANA Considerations
Allocation is expected from IANA for the following Src.DTx functions
codepoints from the "SRv6 Endpoint Behaviors" sub-registry.
Values 68, 69, 70 is suggested for Src.DT6, Src.DT4, Src.DT46
respectively.
+-------+--------+--------------------------+------------+
| Value | Hex | Endpoint function | Reference |
+-------+--------+--------------------------+------------+
| TBD | TBD | Src.DT6 | This draft |
+-------+--------+--------------------------+------------+
| TBD | TBD | Src.DT4 | This draft |
+-------+--------+--------------------------+------------+
| TBD | TBD | Src.DT46 | This draft |
+-------+--------+--------------------------+------------+
Src.DT6 Source address for decapsulation and IPv6 table lookup
e.g. IPv6-MVPN (equivalent to per-VRF VPN label in RFC8556)
Src.DT4 Source address for decapsulation and IPv4 table lookup
e.g. IPv4-MVPN (equivalent to per-VRF VPN label in RFC8556)
Src.DT46 Source address for decapsulation and IP table lookup
e.g. IP-MVPN (equivalent to per-VRF VPN label)
9. Acknowledgements
The authors would like to thank Jeffrey Zhang for his useful
comments.
10. References
10.1. Normative References
[I-D.ietf-bess-srv6-services]
Dawra, G., Filsfils, C., Raszuk, R., Decraene, B., Zhuang,
S., and J. Rabadan, "SRv6 BGP based Overlay services",
draft-ietf-bess-srv6-services-04 (work in progress), July
2020.
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[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-24 (work in
progress), October 2020.
[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.
[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>.
[RFC6625] Rosen, E., Ed., Rekhter, Y., Ed., Hendrickx, W., and R.
Qiu, "Wildcards in Multicast VPN Auto-Discovery Routes",
RFC 6625, DOI 10.17487/RFC6625, May 2012,
<https://www.rfc-editor.org/info/rfc6625>.
[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>.
[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>.
[RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
for Bit Index Explicit Replication (BIER) in MPLS and Non-
MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
2018, <https://www.rfc-editor.org/info/rfc8296>.
[RFC8556] Rosen, E., Ed., Sivakumar, M., Przygienda, T., Aldrin, S.,
and A. Dolganow, "Multicast VPN Using Bit Index Explicit
Replication (BIER)", RFC 8556, DOI 10.17487/RFC8556, April
2019, <https://www.rfc-editor.org/info/rfc8556>.
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10.2. 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
Jingrong Xie
Huawei Technologies
Email: xiejingrong@huawei.com
Mike McBride
Futurewei
Email: mmcbride7@gmail.com
Senthil Dhanaraj
Huawei Technologies
Email: senthil.dhanaraj@huawei.com
Liang Geng
China Mobile
Email: gengliang@chinamobile.com
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
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