Internet DRAFT - draft-sajassi-bess-evpn-vpls-seamless-integ
draft-sajassi-bess-evpn-vpls-seamless-integ
INTERNET-DRAFT Ali Sajassi
Intended Status: Standard Track Samer Salam
Cisco
Nick Del Regno
Verizon
Jorge Rabadan
Alcatel-Lucent
Expires: April 27, 2015 October 27, 2014
(PBB-)EVPN Seamless Integration with (PBB-)VPLS
draft-sajassi-bess-evpn-vpls-seamless-integ-00
Abstract
This draft discusses the backward compatibility of the (PBB-)EVPN
solution with (PBB-)VPLS and provides mechanisms for seamless
integration of the two technologies in the same MPLS/IP network on a
per-VPN-instance basis.
Status of this Memo
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Copyright and License Notice
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Copyright (c) 2013 IETF Trust and the persons identified as the
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 PBB-VPLS Integration with PBB-EVPN . . . . . . . . . . . . . . . 4
3.1 Capability Discovery . . . . . . . . . . . . . . . . . . . . 4
3.2 Forwarding Setup and Unicast Operation . . . . . . . . . . . 5
3.3 Multicast Operation . . . . . . . . . . . . . . . . . . . . 6
3.3.1 Ingress Replication . . . . . . . . . . . . . . . . . . 6
3.3.2 LSM . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 VPLS Integration with EVPN . . . . . . . . . . . . . . . . . . . 7
4.1 Capability Discovery . . . . . . . . . . . . . . . . . . . . 7
4.2 Forwarding Setup and Unicast Operation . . . . . . . . . . . 7
4.3 Multicast Operation . . . . . . . . . . . . . . . . . . . . 7
4.3.1 Ingress Replication . . . . . . . . . . . . . . . . . . 7
4.3.2 LSM . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 VPLS Integration with PBB-EVPN . . . . . . . . . . . . . . . . . 7
5.1 Capability Discovery . . . . . . . . . . . . . . . . . . . . 7
5.2 Forwarding Setup and Unicast Operation . . . . . . . . . . . 7
5.3 Multicast Operation . . . . . . . . . . . . . . . . . . . . 8
5.3.1 Ingress Replication . . . . . . . . . . . . . . . . . . 8
5.3.2 LSM . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 Solution Advantages . . . . . . . . . . . . . . . . . . . . . . 8
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 8
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1 Normative References . . . . . . . . . . . . . . . . . . . 8
9.2 Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1 Introduction
VPLS and PBB-VPLS are widely-deployed L2VPN technologies. Many SPs
who are looking at adopting EVPN and PBB-EVPN want to preserve their
investment in the (PBB-)VPLS networks. Hence, it is required to
provide mechanisms by which (PBB-)EVPN technology can be introduced
into existing L2VPN networks without requiring a fork-lift upgrade.
This document discusses mechanisms for the seamless integration of
the two technologies in the same MPLS/IP network.
VPLS PE
+---+
|PE1|
+---+
/
EVPN/VPLS PE +---------------+ EVPN/VPLS PE
+---+ | | +---+
|PE4|----| MPLS/IP |---|PE5|
+---+ | Core | +---+
| |
+---------------+
/ \
+---+ +---+
|PE2| |PE3|
+---+ +---+
VPLS PE VPLS PE
Figure 1: Seamless Integration of (PBB-)EVPN PEs & (PBB-)VPLS
Section 2 provides the details of the requirements. Section 3
discusses PBB-VPLS integration with PBB-EVPN. Section 4 discusses the
integration of VPLS and EVPN. Section 5 discusses the integration of
VPLS and PBB-EVPN, and finally Section 6 discusses the solution
advantages.
It is worth noting that the scenario where PBB-VPLS is integrated
with EVPN, is for future study and upon market validation. The reason
for that is that deployments which employ PBB-VPLS typically require
PBB encapsulation for various reasons. Hence, it is expected that for
those deployments the evolution path would be from PBB-VPLS towards
PBB-EVPN, rather than EVPN.
1.1 Terminology
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 [KEYWORDS].
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2. Requirements
Following are the key requirements for backward compatibility between
(PBB-)EVPN and (PBB-)VPLS:
1. The solution MUST allow for staged migration towards (PBB-)EVPN on
a site-by-site basis per VPN instance - e.g., new EVPN sites to be
provisioned on (PBB-)EVPN PEs.
2. The solution MUST require no changes to existing VPLS or PBB-VPLS
PEs, not even a software upgrade.
3. The solution MUST allow for the coexistence of PE nodes running
(PBB-)EVPN and (PBB-)VPLS for the same VPN instance and single-homed
segments.
4. The solution MUST support single-active redundancy of multi-homed
networks and multi-homed devices for (PBB-)EVPN PEs.
5. In case of single-active redundancy, the participant VPN instances
MAY span across both (PBB-)EVPN PEs and (PBB-)VPLS PEs as long as
single-active redundancy is employed by (PBB-)EVPN PEs. In case of an
ES link failure, the (PBB-)EVPN PEs will send a BGP mass-withdraw to
the EVPN peers OR MAC advertisement with MAC Mobility extended
community for PBB-EVPN AND an LDP MAC withdrawal to the VPLS peers.
6. The solution SHOULD support all-active redundancy of multi-homed
networks and multi-homed devices for (PBB-)EVPN PEs.
7. In case of all-active redundancy, the participant VPN instances
SHOULD be confined to (PBB-)EVPN PEs only.
These requirements collectively allow for the seamless insertion of
the (PBB-)EVPN technology into brown-field (PBB-)VPLS deployments.
3 PBB-VPLS Integration with PBB-EVPN
In order to support seamless integration with (PBB-)VPLS, the (PBB-
)EVPN PEs MUST support EVPN BGP routes (EVPN SAFI) and SHOULD support
VPLS AD route (VPLS SAFI). All the logic for the integration will
reside on the (PBB-)EVPN PEs side. However, if a VPLS instance is
setup without the use of BGP auto-discovery, it is still possible
(but cumbersome) for (PBB-)EVPN PEs to integrate into that VPLS
instance.
3.1 Capability Discovery
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The (PBB-)EVPN PEs must advertise both the BGP VPLS auto-discovery
(AD) route as well as the BGP EVPN Inclusive Multicast route for a
given VPN instance. The (PBB-)VPLS PEs only advertise the BGP VPLS AD
route, per current standard procedures specified in [RFC4761] and
[RFC6074]. The operator may decide to use the same BGP RT for both
(PBB-)EVPN and (PBB-)VPLS. In this case, when a (PBB-)VPLS PE
receives the EVPN Inclusive Multicast route, it will ignore it on the
basis that it belongs to an unknown SAFI. However, the operator may
use two RTs (one for (PBB-)VPLS and another for (PBB-)EVPN) and
employ RT-constraint in order to prevent EVPN BGP routes from
reaching the (PBB-)VPLS PEs. This provides an optimization in case
required by the scale of the network.
When a (PBB-)EVPN PE receives both a VPLS AD route as well as an EVPN
Inclusive Multicast route from a given remote PE for the same VPN
instance, it MUST give preference to the EVPN route for the purpose
of discovery. This ensures that, at the end of the route exchanges,
all (PBB-)EVPN capable PEs discover other (PBB-)EVPN capable PEs as
well as the (PBB-)VPLS-only PEs for that VPN instance. Furthermore,
all the (PBB-)VPLS-only PEs would discover the (PBB-)EVPN PEs as if
they were standard (PBB-)VPLS nodes. In other words, when the
discovery phase is complete, the (PBB-)EVPN PEs would have discovered
all the PEs in the VPN instance, and their associated capability:
(PBB-)EVPN or VPLS-only. Whereas the (PBB-)VPLS PEs would have
discovered all the PEs in the VPN instance, as if they were all VPLS-
only nodes.
3.2 Forwarding Setup and Unicast Operation
The procedures for forwarding setup and unicast operation on the
(PBB-)VPLS PE are per [RFC4447] and [PBB-VPLS].
The procedures for forwarding state setup and unicast operation on
the (PBB-)EVPN PE are as follows:
- The (PBB-)EVPN PE must establish a pseudowire to a remote PE from
which it has received only a VPLS AD route, for the VPN instance in
question, and set up the label stack corresponding to the pseudowire
FEC. This PW is between B-components of PBB-EVPN PE and PBB-VPLS PE
per section 4 of [PBB-VPLS-PE-MODEL].
- The (PBB-)EVPN PE must set up the label stack corresponding to the
MP2P (PBB-)VPN unicast FEC to any remote PE that has advertised EVPN
AD route.
- If a (PBB-)EVPN PE receives a VPLS AD route followed by an EVPN AD
route from the same PE and a pseudowire is setup to that PE, then the
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(PBB-)EVPN MUST bring that pseudowire operationally down.
- If a (PBB-)EVPN PE receives an EVPN AD route followed by a VPLS AD
route from the same PE, then the (PBB-)EVPN PE will setup the
pseudowire but MUST keep it operationally down.
When the (PBB-)EVPN PE receives traffic over the pseudowires, it
learns the associated MAC addresses in the data-plane. This is
analogous to dynamic learning in IEEE bridges. If the PW belongs to
the same split-horizon group as the EVPN mesh, then the MAC addresses
learnt and associated to the PW will NOT be advertised in the control
plane to any remote (PBB-)EVPN PE. The (PBB-)EVPN PE learns MAC
addresses in the control plane, via the EVPN MAC Advertisement routes
sent by remote (PBB-)EVPN PEs, and updates its MAC forwarding table
accordingly. This is analogous to static learning in IEEE bridges. In
PBB-EVPN, a given B-MAC address can be learnt either over the BGP
control-plane from a remote PBB-EVPN PE, or in the data-plane over a
pseudowire from a remote PBB-VPLS PE. There is no mobility associated
with B-MAC addresses in this context. Hence, when the same B-MAC
address shows up behind both a remote PBB-VPLS PE as well as a PBB-
EVPN PE, the local PE can deduce that there is an anomaly in the
network.
3.3 Multicast Operation
3.3.1 Ingress Replication The procedures for multicast operation on the
(PBB-)VPLS PE, using ingress replication, are per [RFC4761],
[RFC4762], and [PBB-VPLS].
The procedures for multicast operation on the PBB-EVPN PE, for
ingress replication, are as follows:
- The PBB-EVPN PE builds a replication sub-list per I-SID to all the
remote PBB-EVPN PEs in a given VPN instance, as a result of the
exchange of the EVPN Inclusive multicast routes, as described in
[PBB-EVPN]. This will be referred to as sub-list A. It comprises MP2P
tunnels used for delivering PBB-EVPN BUM traffic [EVPN].
- The PBB-EVPN PE builds a replication sub-list per VPN instance to
all the remote PBB-VPLS PEs , as a result of the exchange of the VPLS
AD routes. This will be referred to as sub-list B. It comprises
pseudowires from the PBB-EVPN PE in question to all the remote PBB-
VPLS PEs in the same VPN instance.
- The PBB-EVPN PE may further prune sub-list B, on a per I-SID basis,
if [MMRP] is run over the PBB-VPLS network. This will be referred to
as sub-list C. This list comprises a pruned set of the pseudowires in
sub-list B.
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The replication list, maintained per I-SID, on a given PBB-EVPN PE
will be the union of sub-list A and sub-list B if [MMRP] is NOT used,
and the union of sub-list A and sub-list C if [MMRP] is used. Note
that the PE must enable split-horizon over all the entries in the
replication list, across both pseudowires and MP2P tunnels.
3.3.2 LSM Will be covered in a future revision of this document.
4 VPLS Integration with EVPN
4.1 Capability Discovery
The procedures for capability discovery are per Section 3.1 above.
4.2 Forwarding Setup and Unicast Operation
The operation here is largely similar to that of PBB-EVPN integration
with PBB-VPLS, with the exception of the need to handle MAC mobility,
the details of which will be covered in a future revision of this
document.
4.3 Multicast Operation
4.3.1 Ingress Replication
The operation is per the procedures of Section 3.3.1 above for the
scenario WITHOUT [MMRP]. The replication list is maintained per VPN
instance, rather than per I-SID.
4.3.2 LSM Will be covered in a future revision of this document.
5 VPLS Integration with PBB-EVPN
5.1 Capability Discovery
The procedures for capability discovery are per Section 3.1 above.
5.2 Forwarding Setup and Unicast Operation
The operation here is largely similar to that of PBB-EVPN integration
with PBB-VPLS, with a few exceptions listed below:
- When a PW is setup between a PBB-EVPN PE and a VPLS PE, it gets
setup between the I-component of PBB-EVPN PE and the bridge component
of VPLS PE.
- The MAC mobility needs to be handled. The details of which will be
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covered in a future revision of this document.
5.3 Multicast Operation
5.3.1 Ingress Replication
The operation is per the procedures of Section 3.3.1 above for the
scenario WITHOUT [MMRP]. The replication list is maintained per I-SID
on the PBB-EVPN PEs and per VPN instance on the VPLS PEs.
5.3.2 LSM Will be covered in a future revision of this document.
6 Solution Advantages
The solution for seamless integration of (PBB-)EVPN with (PBB-)VPLS
has the following advantages:
- When ingress replication is used for multi-destination traffic
delivery, the solution reduces the scope of [MMRP] (which is a soft-
state protocol) to only that of existing VPLS PEs, and uses the more
robust BGP-based mechanism for multicast pruning among new EVPN PEs.
- It is completely backward compatible.
- New PEs can leverage the extensive multi-homing mechanisms and
provisioning simplifications of PBB-EVPN:
1. Auto-sensing of MHN / MHD
2. Auto-discovery of redundancy group
3.Auto-provisioning of DF election and VLAN carving
7 Security Considerations
No new security considerations beyond those for VPLS and EVPN.
8 IANA Considerations
This document has no actions for IANA.
9 References
9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
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Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
"Encapsulation Methods for Transport of Ethernet over MPLS
Networks", RFC 4448, April 2006.
[RFC4447] Martini, et al., "Pseudowire Setup and Maintenance using
the Label Distribution Protocol", draft-ietf-pwe3-
rfc4447bis-02.txt, October 2013.
[EVPN] Sajassi et al., "BGP MPLS Based Ethernet VPN", draft-ietf-
l2vpn-evpn-04.txt, work in progress, July, 2013.
[PBB-EVPN] Sajassi et al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn-
05.txt, work in progress, October, 2013.
9.2 Informative References
[MMRP] Clause 10 of "IEEE Standard for Local and metropolitan area
networks - Media Access Control (MAC) Bridges and Virtual Bridged
Local Area Networks", IEEE Std 802.1Q, 2013.
[PBB-VPLS-PE-MODEL] Balus, F., Sajassi, S., Bitar, N., "Extensions to
VPLS PE model for Provider Backbone Bridging", RFC xxxx, June 2013.
[PBB-VPLS] Sajassi, et al., "VPLS Interoperability with Provider
Backbone Bridges", draft-ietf-l2vpn-pbb-vpls-interop-05.txt, work in
progress, October, 2013.
Authors' Addresses
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Samer Salam
Cisco
595 Burrard Street, Suite 2123
Vancouver, BC V7X 1J1, Canada
Email: ssalam@cisco.com
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Nick Del Regno
Verizon
400 International Pkwy
Richardson, TX 75089, US
Email: nick.delregno@verizon.com
Jorge Rabadan
Alcatel-Lucent
400 International Pkwy
Richardson, TX 75089, US
Email: jorge.rabadan@alcatel-lucent.com
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