VPLS Signaling

8/8/2019 VPLS Signaling

1/26

Interdomain LDP-BGP VPLS

Interworking

Amit Shukla

Juniper Networks


2/26

2

Background

Virtual private LAN service (VPLS) glues togetherseveral individual LANs across a packet-sw itchednetwork to appear and function as a single LAN

There are two standards for VPLS control planethat 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

The data plane used by both these standards issame

Flooding of unknown unicast, learning/aging MACaddresses, etc.

A key notion in the data plane is of split-horizonforwarding

MPLS pseudo-wire encapsulation


3/26

3

Business Drivers for LDP-BGP VPLSinterworking solution

To interconnect domains running a

different VPLS control plane technologies

To expand LDP-based VPLS service out of

metro domain to WAN in a scalable andefficient manner.By using BGP-VPLS.


4/26

4

Expanding VPLS service using BGP-VPLS

Why BGP-VPLS in WAN

ScalableAuto-discovery

Inter-provider support

Why LDP-VPLS in Metro Legacy

Proposed solution requires no changes inMetro network running LDP-VPLS


5/26

5

Interconnecting Domains running different VPLS

control plane technologies (BGP-VPLS and LDP-VPLS)

Existing inter-AS VPLS options are not

designed for ASes running different VPLStechnologies (BGP-VPLS and LDP-VPLS) Option-A can be used but doesnt scale.

It is apparent that interworking function isrequired between BGP-VPLS and LDP-VPLS.

MPE1

M-ASBR

Metro-A

(LDP-VPLS)

MPE2LDP-VPLS PW

VPLS-A

VPLS-A CPE1

WAN core

(BGP-VPLS)

CPE3

VPLS-A

C-ASBR

BGP-VPLS PWVPLS-A

MPE3

VPLS-A

VPLS-ACPE2


6/26

6

Extending the reach of LDP-VPLS metro-domain toWAN via BGP-VPLS to enable region/nation-wideVPLS service

BGP Session

LDP Session

C-ASBR2C-ASBR1

M-ASBR1M-ASBR2

WAN

(BGP-VPLS)

Metro-B(LDP-VPLS)

RR

C-ASBR3

MPE3

MPE4

MPE1

MPE2

Metro-A

(LDP-VPLS)

MPE5

M-ASBR3

MPE6

Metro-C(LDP-VPLS)

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A


7/26

7

Overview of LDP-BGP VPLS interworking

Interworking operation localized at WAN border-

router (ASBRs)

Proposed Interworking mechanism require nochanges in both

LDP/BGP VPLS control plane specifications (and) Current LDP-VPLS Metro network design

MPE1

M-ASBR

METRO-A

(LDP-VPLS)

MPE2

VPLS-A

VPLS-A CPE1

WAN core

(BGP-VPLS)

CPE2

VPLS-A

C-ASBR

VPLS-A


8/26

8

Control Plane Operation 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

Scalable Only one additional LDP session provisioned per LDP-VPLS

PE Only one additional PW setup on each LDP-VPLS PE per

VPLS

MPE1

M-ASBR

METRO-A

(LDP-VPLS)

MPE2LDP-VPLS PW

VPLS-A

VPLS-A CPE1

WAN core

(BGP-VPLS)

CPE2VPLS-A

C-ASBR

BGP-VPLS PW

VPLS-A


9/26

9

How BGP-VPLS view LDP-VPLS

BGP-VPLS view the LDP-VPLS domain like

a VPLS site w ith a single CE.

LDP-VPLS BGP-VPLS

BGP Site-ID:2

Advertised BGP

SignalingRoute

CPE1

CPE2

C-ASBR

MPE1

MPE2

BGP Site-ID:3

VPLS site

(Interworking ASBR)

BGP-VPLS pseudow ire LDP-VPLS pseudow ire

Metro-ABGP Site-ID:1 WAN

VPLS-AVPLS-A

VPLS-A


10/26

10

How LDP-VPLS view BGP-VPLS

LDP-VPLS view the BGP-VPLS domain likea VPLS site w ith a single CE.

LDP-VPLS BGP-VPLS

CPE1

CPE2

C-ASBR

MPE1

MPE2

VPLS site

(Interworking ASBR)

BGP-VPLS pseudow ire LDP-VPLS pseudow ire

Metro-A WAN

VPLS-A

VPLS-A

VPLS-A


11/26

11

Data Plane Operation Fundamental data operations perform on each

incoming frame on a PW:

LDP and BGP VPLS PWs terminates on the interworkingASBR

Common MAC-table maintained to stitch the set of fully-meshed LDP and BGP VPLS pseudowires

MAC-table populated via learning a source-MAC address

from incoming frame

Destination MAC-address lookup to determine destinationpseudowire


12/26

12

Mesh Group

Mesh group concept introduced on aninterworking ASBR

Groups all the fully meshed PWs of each domain.

Existing split-horizon forw arding rule applicablefor each mesh group

Allows forwarding across pseudowires part of a different

mesh-group. Prohibits forwarding across pseudowires part of a same

mesh-group.


13/26

13

Mesh Groups: Flooding

Assume CE-1 sends a broadcast ARP request packet. It will be flooded byMPE1, to all PEs in Metro-A domain (including C-ASBR) as its fully-meshed.C-ASBR receives this packet from MPE1 and forwards it to all the

mesh-groups (PWs) except the one in which packet is received, as aresult packet is forwarded on all PW s part of mesh-group WAN .

Upon receiving this packet from MPE1, C-ASBR learns the CE-1 Mac-addressvia MPE1 PW. Destination forwarding table on C-ASBR looks like:

MPE1

MPE2

C-ASBR

CPE1

CPE2

LDP-VPLS PW BGP-VLS PW

M esh-group M etro-A M esh-group W AN

Floodingpacket flowFrom CE-1

CE-1

CE-2

CE-3

CE-4

PW(MPE1)MAC(CE-1)

Next HopMAC-Addr

VPLS-A

VPLS-A

VPLS-A

VPLS-A


14/26

14

Mesh Groups: Normal Known Unicast

Here, CE-3 is sending a unicast packet to CE-1 and its assumed thatCE-1s MAC address has been learned on all PEs. CPE1 has learnedCE-1s MAC via C-ASBR so it forwards the packet to C-ASBR.

C-ASBR forwards this unicast packet on MPE1 PW since both

incoming and outgoing PWs are in different mesh-groups.

MPE1

MPE2

C-ASBR

CPE1

CPE2

LDP-VPLS PWBGP-VLS PW

Mesh-group M etro-A M esh-group W AN

Unicast packet

CE-1

CE-2

CE-3

CE-4

VPLS-A

VPLS-A

VPLS-A

VPLS-A

PW(MPE1)Mac(CE-1)

Next-hopMac-addr


15/26

15

Interconnecting multiple metro domains using a singleinterworking ASBR.

Each metro domain is mapped to a dedicated mesh group.

MPE1 M-ASBR1

METRO-A(LDP-VPLS)

MPE3

M-ASBR2

METRO-B(LDP-VPLS)

MPE2

MPE4

C-ASBR

CPE3

CPE1

CPE2

WAN(BGP-VPLS)

LDP-VPLS PW

BGP-VPLS PW

LDP-BGP VPLS interworkingusing common-mac table

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A

Mesh Groups Full-mesh Domains


16/26

16

Interworking Device With Attached CEs

MPE1

M-ASBR

METRO-A

(LDP-VPLS)

MPE2 LDP-VPLS PW

VPLS-A

VPLS-A

CPE1

WAN

(BGP-VPLS)

CPE2

VPLS-A

VPLS-A

C-ASBR

BGP-VLS PW

Interworking ASBR can provide PE routerfunctionality at the same time performing the

LDP-BGP VPLS interworking task.

VPLS-A


17/26

17

MPE1

M-ASBRMETRO-A

(LDP-VPLS)

MPE2 LDP-VPLS PW

VPLS-A

VPLS-A

CPE1

WAN

(BGP-VPLS)

CPE2

VPLS-A

VPLS-AC-ASBR

BGP-VLS PW

CPE1

Resiliency

Interworking ASBR becomes critical for

inter-domain VPLS service Resiliency becomes critical to complete this

solution

Solution is redundancy


18/26

18

Background: CE-device resiliency usingBGP-VPLS multihoming

BGP-VPLS multihoming procedures enables loop-free redundancy to attached CE devices w ithout

relying on Spanning Tree Protocol (STP).

CE1

PE1

PE3CE3

PE2

CE device dual-homed to

PE devices for redundancy PE4

CE2


19/26

19

Redundancy using BGP-VPLS multihoming

MPE1

M-ASBR

METRO-A

(LDP-VPLS)

MPE2 LDP-VPLS PW

VPLS-A

VPLS-A

CPE1

WAN

(BGP-VPLS)

CPE2

VPLS-A

VPLS-AC-ASBR1

BGP-VLS PW

BGP Site-1

C-ASBR2

Existing BGP-VPLS multihoming procedure usedw ith no changes to enable redundancy for LDP-

VPLS metro.


20/26

20

Why use BGP-VPLS multihoming Scalable: Supports multiple metro domains

Flexible: Precise control over designated forwarder

Load balancing: Distribution of VPLS customers

MPE1

M-ASBR1

METRO-A

(LDP-VPLS)

MPE3 M-ASBR2

METRO-B

(LDP-VPLS)

MPE2

MPE4

C-ASBR1

WAN

(BGP-VPLS)

LDP-VPLS PW

BGP-VPLS PW

C-ASBR2VPLS-A

VPLS-A

VPLS-A

VPLS-A

BGP SITE 1

BGP SI TE 2

Resiliency for multiple LDP-VPLS Metros

VPLS-A

VPLS-A

CPE1

CPE2


21/26

21

Extending the reach of LDP-VPLS metro-domain to

WAN via BGP-VPLS

BGP Session

LDP Session

C-ASBR2 C-ASBR1

M-ASBR1

M-ASBR2

WAN

(BGP-VPLS)

Metro-B(LDP-VPLS)

RR

C-ASBR3

MPE1

MPE2

MPE3

MPE4

Metro-A

LDP-VPLS)

Interdomain LDP-BGPinterworking


MPE6

M-ASBR3

MPE7

Metro-C(LDP-VPLS)

Scalable way to enable region/ nation-w ide VPLSservice using BGP-VPLS in WAN.

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-A

VPLS-AMPE5



22/26

22

Resiliency using BGP-VPLS multi-homing

BGP Session

LDP Session

C-ASBR2

C-ASBR1

M-ASBR1

M-ASBR2

WAN

(BGP-VPLS)

Metro-B(LDP-VPLS)

RR

C-ASBR3

MPE1

MPE2

MPE3

MPE4

Metro-A

LDP-VPLS)

Redundant InterworkingASBRs

MPE5

M-ASBR3

MPE6

Metro-C(LDP-VPLS)

C-ASBR3

Enabling resiliency for LDP-VPLS domain Metro-B

VPLS-A

VPLS-A

VPLS-AVPLS-A

VPLS-A

VPLS-A


23/26


24/26

24

Summary

I t works w ith existing LDP-VPLS standard

Scalable (and minor changes to metro design) Only one (or couple) additional LDP sessions per PE in

metro

Only one (or couple) additional PWs setup per PE per

VPLS

Easier to manage Adding new sites or PE in a metro area does not require

any provisioning on other remote Metro area BGP auto-discovery simplifies provisioning task in WAN


25/26

25

Summary (Cont)

Resilient

Native BGP-VPLS multi-homing support provides loop-free redundancy without the need of Spanning-TreeProtocol

Efficient Interworking ASBR provides dual functionality of PErouter and LDP-BGP interworking

Multiple metro-domains can be interconnected via

single interworking ASBR BGP-VPLS with point-to-multipoint LSP instead ofingress replication for multicast/broadcast unknown


26/26

26

Thank You !

Documents

VPLS Signaling