Vpls Service Overview; Vpls Over Mpls - Alcatel-Lucent 7750 SR OS Service Manual

VPLS Service Overview

VPLS Service Overview
Virtual Private LAN Service (VPLS) as described in Internet Draft draft-ietf-ppvpn-vpls-ldp-
01.txt, is a class of virtual private network service that allows the connection of multiple sites in a
single bridged domain over a provider-managed IP/MPLS network. The customer sites in a VPLS
instance appear to be on the same LAN, regardless of their location. VPLS uses an Ethernet
interface on the customer-facing (access) side which simplifies the LAN/WAN boundary and
allows for rapid and flexible service provisioning.
VPLS offers a balance between point-to-point Frame Relay service and outsourced routed services
(VPRN). VPLS enables each customer to maintain control of their own routing strategies. All
customer routers in the VPLS service are part of the same subnet (LAN) which simplifies the IP
addressing plan, especially when compared to a mesh constructed from many separate point-to-
point connections. The VPLS service management is simplified since the service is not aware of
nor participates in the IP addressing and routing.
A VPLS service provides connectivity between two or more SAPs on one (which is considered a
local service) or more (which is considered a distributed service) 7750 SR routers. The connection
appears to be a bridged domain to the customer sites so protocols, including routing protocols, can
traverse the VPLS service.
Other VPLS advantages include:
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VPLS over MPLS

The VPLS architecture proposed in draft-ietf-ppvpn-vpls-ldp-0x.txt specifies the use of provider
equipment (PE) that is capable of learning, bridging, and replication on a per-VPLS basis. The PE
routers that participate in the service are connected using MPLS Label Switched Path (LSP)
tunnels in a full-mesh composed of mesh SDPs or based on an LSP hierarchy (Hierarchical VPLS
(H-VPLS)) composed of mesh SDPs and spoke SDPs.
Multiple VPLS services can be offered over the same set of LSP tunnels. Signaling specified in
draft-martini-l2circuit-encap-mpls-0x.txt is used to negotiate a set of ingress and egress VC labels
on a per-service basis. The VC labels are used by the PE routers for de-multiplexing traffic
arriving from different VPLS services over the same set of LSP tunnels.
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VPLS is a transparent, protocol-independent service.
There is no Layer 2 protocol conversion between LAN and WAN technologies.
There is no need to design, manage, configure, and maintain separate WAN access
equipment, thus, eliminating the need to train personnel on WAN technologies such as
Frame Relay.
7750 SR OS Services Guide