Transcript
Virtual Private LAN Service (VPLS)
. What is VPLS? . What Is Driving VPLS? . Why Deploy VPLS? . VPLS Features
Introduction
Virtual Private LAN Service (VPLS)
. What is VPLS?
Broadcast domain 1 Broadcast domain 1
. VPLS extends the Ethernet broadcast domain between potentially geographically distant LAN segments
. Allows standard Ethernet devices communicate with each other as if connected to a common LAN segment
VPLS Reference Model
. The set of PE devices interconnected via PWs appears as a single emulated LAN to a customer
Ref: RFC 4762 Virtual Private LAN Service over LDP, January 2007
VPLS Reference Model
. The set of PE devices interconnected via PWs appears as a single emulated LAN to a customer
Ref: RFC 4762 Virtual Private LAN Service over LDP, January 2007
What Is Driving VPLS?
The Expanding Use of Ethernet
Access Aggregation PSN Aggregation Access
Why Deploy VPLS?
Feature Benefits
MPLS core network emulates . Overcomes distance limitations of
a flat LAN segment Ethernet-switched networks . Enables Virtual Private LAN Services . Customers maintain routing andadministrative autonomy
Extends Ethernet broadcast capability across WAN .Point to MultipointConnectivity . Connects each customer site to many or all other customer sites . A single CE-PE link transmits Ethernetpackets to multiple remote CE routers . Fewer connections required to get fullconnectivity among customer sites . OpEx Savings
Multipoint plug-and-play provisioning . Adding, removing or relocating a CErouter requires configuring only thedirectly attached PE router . OpEx Savings
“Flat” VPLS Deployment Model:
Customers Attach Directly to VPLS Service
Hierarchical VPLS Deployment Model:Hub-and-Spoke
Why H-VPLS? Greater Scale
Flat VPLS H-VPLS
. Full PW mesh from the edge . Full PW mesh only within core . Higher signaling overhead . Minimizes signaling overhead . Packet replication done at the edge . Packet replication done in the core only . Node discovery and provisioning . Partitions node discovery into smaller
extend end-to-end domains
H-VPLS Access: QinQ or MPLS at Edge
“L2” VPLS . H-VPLS with QinQ Access (QinQ) (IP/MPLS Core) U-PE A N-PE 1 . Access domain defined by CE STP IEEE 802.1ad (QinQ) (QinQ)
PW
CE
U-PE B
N-PE 2
MPLS VPLS . H-VPLS with MPLS Access (H&S PW) (IP/MPLS Core) U-PE A N-PE 1
. Uses PW EoMPLS circuit CE to backhall traffic from MPLS
PW
U-PE to N-PE CE
U-PE B
N-PE 2
VPLS Features
. VPLS Autodiscovery
. Pseudowire Redundancy (see AToM for example)
. N-PE Redundancy with MAC Address Withdrawal
VPLS Autodiscovery and Signaling
. Autodiscovery: BGP is the configuration agent
True autodiscovery of VPN members
No need to explicitly list them
. Signaling: LDP sets up a standard PW
PWs signal other information such as
attachment circuit state, sequencing
information, etc.
Cisco IOS supports targeted LDP for
AToM and VPLS
Discovery & Signaling
. Discovery & signaling are separable parts of L2VPN
establishment
Discovery (finding members of an L2VPN) is a
point-to-multipoint task
Signaling (establishing the pseudowires) is apoint-to-point task . By separating the tasks, you can choose a suitableprotocol for each: BGP, RADIUS, etc. for Discovery LDP, L2TPv3 for PW Signaling
LDP vs. BGP for PW Signaling
. For VPLS scaling,full mesh is not a significant problem
. LDP provideslighter-weightsolution
LDP BGP
Point-to-Point Information Only Broadcasts All Information to All Peers
No Policy Complex Policy,Often ChangingInformation Advertised
Mostly Idle Can Have Significant Churn Due to Broadcast
H-VPLS N-PE Redundancy for MPLS Access
Cust VFI/MPLS Access/AggMPLS Core
bridgeNetwork
module
PE
node
P
u-PE n-
node
PE1
PW
nPE2
Feature Description: Upon PW failure detection by u-PE, PW
redundancy selects the backup n-PE, and then a MAC address
withdrawal message is sent by the u-PE to the n-PE2 backup
This H-VPLS redundancy feature has three components:1.PW loss-of-connectivity detection (includes signaling of PWStatus)2.PW Redundancy anchored at the u-PE and terminated at nPE1 & n-PE2
Presentation_ID ⓒ 2007 Cisco Systems, Inc. All rights reserved. Cisco Confidential
3.MAC Address Withdrawal
References
Virtual Private LAN Service (VPLS)
. RFC 4447 Pseudowire Setup and Maintenance Using LDP,
April 2006
http://www.ietf.org/rfc/rfc4447.txt
. RFC 4448 Encapsulation of Ethernet over MPLS,
April 2006
http://www.ietf.org/rfc/rfc4448.txt
. RFC 4762 Virtual Private LAN Service over LDP,
January 2007
http://www.ietf.org/rfc/rfc4762.txt
