Interdomain LDP-BGP VPLS Interworking Amit Shukla Juniper Networks

26 Pages·2008·3.36 MB·English

Interdomain LDP-BGP VPLS
Interworking
Amit Shukla
Juniper Networks
Background
(cid:131) Virtual private LAN service (VPLS) glues together
several individual LANs across a packet-switched
network to appear and function as a single LAN
(cid:131) There are two standards for VPLS control plane
that are deployed today:
• BGP-based (BGP-VPLS): uses BGP for auto-discovery
and signaling of PWs (RFC 4761)
• LDP-based (LDP-VPLS): uses LDP for signaling of PWs
(RFC 4762), with discovery via provisioning
(cid:131) The data plane used by both these standards is
same
• Flooding of unknown unicast, learning/aging MAC
addresses, etc.
• A key notion in the data plane is of split-horizon
forwarding
• MPLS pseudo-wire encapsulation
2
Business Drivers for LDP-BGP VPLS
interworking solution
(cid:131) To interconnect domains running a
different VPLS control plane technologies
(cid:131) To expand LDP-based VPLS service out of
metro domain to WAN in a scalable and
efficient manner.
• By using BGP-VPLS.
3
Expanding VPLS service using BGP-VPLS
(cid:131) Why BGP-VPLS in WAN
• Scalable
• Auto-discovery
• Inter-provider support
(cid:131) Why LDP-VPLS in Metro
• Legacy
(cid:131) Proposed solution requires no changes in
Metro network running LDP-VPLS
4
Interconnecting Domains running different VPLS
control plane technologies (BGP-VPLS and LDP-
VPLS)
(cid:131) Existing inter-AS VPLS options are not
designed for ASes running different VPLS
technologies (BGP-VPLS and LDP-VPLS)
• Option-A can be used but doesn’t scale.
(cid:131) It is apparent that interworking function is
required between BGP-VPLS and LDP-VPLS.
VPLS-A
VPLS-A CPE1
MPE1
CPE2 VPLS-A
M-ASBR C-ASBR
WAN core
MPE3 Metro-A
(BGP-VPLS)
(LDP-VPLS)
LDP-VPLS PW CPE3
MPE2 VPLS-A
VPLS-A BGP-VPLS PW
VPLS-A
5
Extending the reach of LDP-VPLS metro-domain to
WAN via BGP-VPLS to enable region/nation-wide
VPLS service
VPLS-A
VPLS-A
MPE3
MPE1
WAN
(BGP-VPLS)
M-ASBR2
M-ASBR1
RR
Metro-B
(LDP-VPLS)
C-ASBR2
C-ASBR1
Metro-A
(LDP-VPLS)
MPE2
MPE4
VPLS-A
VPLS-A
C-ASBR3 MPE5 VPLS-A
M-ASBR3
BGP Session
Metro-C
VPLS-A
(LDP-VPLS)
LDP Session 6
MPE6
Overview of LDP-BGP VPLS interworking
(cid:131) Interworking operation localized at WAN border-
router (ASBRs)
(cid:131) Proposed Interworking mechanism require no
changes in both
• LDP/BGP VPLS control plane specifications (and)
• Current LDP-VPLS Metro network design
Interworking device
VPLS-A
VPLS-A CPE1
MPE1
C-ASBR
M-ASBR
WAN core
METRO-A
(BGP-VPLS)
(LDP-VPLS)
CPE2
MPE2 VPLS-A
7
VPLS-A
Control Plane Operation
(cid:131) Interworking Autonomous System Border Router
(interworking ASBR)
• Supports both LDP and BGP VPLS control planes
• Setup full-mesh of LDP/BGP PWs per interdomain VPLS
(cid:131) Scalable
• Only one additional LDP session provisioned per LDP-VPLS
PE
• Only one additional PW setup on each LDP-VPLS PE per
VPLS
LDP + BGP Control planes
VPLS-A CPE1 VPLS-A
MPE1
C-ASBR
M-ASBR
WAN core
METRO-A
(BGP-VPLS)
(LDP-VPLS)
VPLS-A
LDP-VPLS PW CPE2
MPE2
BGP-VPLS PW
8
VPLS-A
How BGP-VPLS view LDP-VPLS
(cid:131) BGP-VPLS view the LDP-VPLS domain like
a VPLS site with a single CE.
LDP-VPLS BGP-VPLS
BGP Site-ID:2
MPE1 CPE1
VPLS-A (Interworking ASBR) VPLS-A
C-ASBR
BGP Site-ID:1
WAN
Metro-A
BGP Site-ID:3
VPLS-A VPLS-A
MPE2 CPE2
Advertised BGP
Signaling
Route
<Local-site:1, Offset:1, Label-base:800>
VPLS site BGP-VPLS pseudowire LDP-VPLS pseudowire 9
How LDP-VPLS view BGP-VPLS
(cid:131) LDP-VPLS view the BGP-VPLS domain like
a VPLS site with a single CE.
LDP-VPLS BGP-VPLS
MPE1 CPE1
VPLS-A (Interworking ASBR) VPLS-A
C-ASBR
WAN
Metro-A
VPLS-A VPLS-A
MPE2 CPE2
VPLS site BGP-VPLS pseudowire LDP-VPLS pseudowire 10