SRv6 and MPLS interworking for VPN service
draft-pzm-bess-spring-interdomain-vpn-00
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SPRING WG Shaofu. Peng
Internet-Draft Zheng. Zhang
Intended status: Standards Track Greg. Mirsky
Expires: April 26, 2020 ZTE Corporation
October 24, 2019
SRv6 and MPLS interworking for VPN service
draft-pzm-bess-spring-interdomain-vpn-00
Abstract
This document describes a method to achieve an inter-domain
connection for a VPN (Virtual Private Network) service.
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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and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 26, 2020.
Copyright Notice
Copyright (c) 2019 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 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1. SRv6 to SR-MPLS domain signaling . . . . . . . . . . . . 2
2.2. SR-MPLS to SRv6 domain signaling . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Normative References . . . . . . . . . . . . . . . . . . 4
5.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
[I-D.agrawal-spring-srv6-mpls-interworking] describes SRv6 and MPLS/
SR-MPLS interworking and co-existence procedures. The document
leverages the function defined in
[I-D.ietf-spring-srv6-network-programming] to give guidance to the
forwarding in routers.
[RFC4364] describes a method by which a Service Provider may use an
IP backbone to provide IP Virtual Private Networks (VPNs) for its
customers. When SRv6 and SR-MPLS are co-existed in the backbone,
controller or a control plane, for example, using BGP, should be used
to instantiate the VPN service as described in
[I-D.agrawal-spring-srv6-mpls-interworking].
In case of option B inter-domain interconnection [RFC4364], only ASBR
needs to do the stitching work between two ASes. Thus PEs in SRv6
and SR-MPLS domains do not have to support both SRv6 and SR-MPLS
functions. This document discusses the use of BGP for achieving VPN
service through option B defined in [RFC4364] across a backbone that
includes SRv6 and SR-MPLS domains.
2. Specification
2.1. SRv6 to SR-MPLS domain signaling
[I-D.ietf-bess-srv6-services] defines the new TLVs for the BGP
Prefix-SID Attribute that can be used to signaling of SRv6 SID for L3
and L2 services. In this document, we use L3 case as the example,
the procedures for L2 are the same as in L3 scenario.
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+-------------+ +-------------+
| AS1 | | AS2 |
| | | |
CE1+----+PE1 ASBR1+---+ASBR2 PE2+----+CE2
| | | |
| SRV6 | | SR-MPLS |
+-------------+ +-------------+
Figure 1
For example, CE1 and CE2 are connected through a backbone that
includes AS1 and AS2. AS1 supports SRv6 only, and AS2 supports SR-
MPLS only. ASBR1 supports both SRv6 and SR-MPLS capabilities, but
ASBR2 supports SR-MPLS capability only.
For a prefix advertised by CE1 to PE1, PE1 assigns SID with End.DT4
(or End.DT6) defined in [I-D.ietf-spring-srv6-network-programming]
section 4 (e.g., End.DT4 is used while the prefix is IPv4 prefix,
End.DT6 is used while the prefix is IPv6 prefix), and advertises it
to ASBR1. Because ASBR2 supports SR-MPLS function only, the SRv6 SID
advertised by ASBR1 cannot be executed by ASBR2 because ASBR2 cannot
recognize it.
ASBR1 uses specific execution function that is different from the
function used in a single SRv6 domain or a single SR-MPLS domain. In
this situation, ASBR1 assigns an MPLS label for the prefix received
from PE1 and advertises it to ASBR2. The MPLS label has local
significance that indicates this packet is associated with an SRv6
SID list which leads the packet from ASBR1 to PE1. The advertisement
is the same as the format in [I-D.ietf-idr-bgp-prefix-sid].
When a data flow packet which has the destination to CE1 is received
by ASBR1, ASBR1 recognizes the MPLS label, removes the label and adds
an SRH to the packet, then forwards it to PE1.
2.2. SR-MPLS to SRv6 domain signaling
In the same example, PE2 advertises a prefix received from CE2 with
assigned SID to ASBR2 according to [I-D.ietf-idr-bgp-prefix-sid],
ASBR2 assigns SID for this prefix and advertises it to ASBR1. When
ASBR1 advertises this prefix to PE1, ASBR1 should assign an SRv6 SID
for it. The SID indicates the new execution function (e.g., END.RM,
it indicates that MPLS should replace the SRH) for exchanging the
packet header from SRH to MPLS list. The new function format is like
the defination in [I-D.ietf-spring-srv6-network-programming] section
4.
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When a data flow packet, which has the destination to CE2, is
received by ASBR1, ASBR1 recognizes the SRv6 SID, removes the SRH and
adds a or a list of MPLS label in the packet, and forwards it to PE2.
3. IANA Considerations
There is no IANA consideration.
4. Security Considerations
This document introduces no new security consideration beyond those
already specified in [RFC4364], [I-D.ietf-idr-bgp-prefix-sid],
[I-D.ietf-spring-srv6-network-programming],
[I-D.ietf-bess-srv6-services] and
[I-D.agrawal-spring-srv6-mpls-interworking].
5. References
5.1. Normative References
[I-D.ietf-bess-srv6-services]
Dawra, G., Filsfils, C., Brissette, P., Agrawal, S.,
Leddy, J., daniel.voyer@bell.ca, d.,
daniel.bernier@bell.ca, d., Steinberg, D., Raszuk, R.,
Decraene, B., Matsushima, S., Zhuang, S., and J. Rabadan,
"SRv6 BGP based Overlay services", draft-ietf-bess-
srv6-services-00 (work in progress), October 2019.
[I-D.ietf-idr-bgp-prefix-sid]
Previdi, S., Filsfils, C., Lindem, A., Sreekantiah, A.,
and H. Gredler, "Segment Routing Prefix SID extensions for
BGP", draft-ietf-idr-bgp-prefix-sid-27 (work in progress),
June 2018.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J.,
daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
Network Programming", draft-ietf-spring-srv6-network-
programming-04 (work in progress), October 2019.
[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>.
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5.2. Informative References
[I-D.agrawal-spring-srv6-mpls-interworking]
Agrawal, S., Ali, Z., Filsfils, C., daniel.voyer@bell.ca,
d., and Z. Li, "SRv6 and MPLS interworking", draft-
agrawal-spring-srv6-mpls-interworking-01 (work in
progress), July 2019.
Authors' Addresses
Shaofu Peng
ZTE Corporation
Email: peng.shaofu@zte.com.cn
Zheng Zhang
ZTE Corporation
Email: zzhang_ietf@hotmail.com
Greg Mirsky
ZTE Corporation
Email: gregimirsky@gmail.com
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