Juniper JUNOSE 11.2.X BGP AND MPLS, Руководство по настройке

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VPLS Domains
Typically, a VPLS domain is associated with customers who want to use Ethernet-based
layer 2 VPNs to connect geographically dispersed sites in their organization across an
MPLS-based service provider core, also known as an MPLS backbone. Each VPLS domain
consists of the set of PE routers running the corresponding VPLS instance that participates
in that domain. In BGP-signaled VPLS, a VPLS domain is identified by the route target
extended community, similarly to how a layer3 VPN domain is identified in layer 3VPNs.
Figure 128 on page 574depicts two VPLS domains: VPLS A and VPLS B. The VPLS A domain
connects Customer A’s Boston and Chicago offices, and consists of provider edge routers
PE 1 and PE 2, each of which runs a VPLS instance named vplsA. Similarly, the VPLS B
domain connects Customer B’s Boston and Chicago offices, and consists of provider
edge routers PE 1 and PE 2, each of which also runs a VPLS instance named vplsB.
Customer Edge Devices
Figure 128 on page 574 shows four customer edge (CE) devices: CE 1, CE 2, CE 3, and CE
4. Each CE device is located at the edge of a customer site, and participates in one or
more VPLS domains. In the sample topology, CE 1 and CE 3 are members of the VPLS A
domain, and CE 2 and CE 4 are members of the VPLS B domain.
A CE device can be a single host, a switch, or, most typically, a router. Each CE device is
directly connected to a VPLS edge router by means of an Ethernet or bridged Ethernet
network interface, but does not run VPLS. From the perspective of the CE device, the
entire VPLS network appears to be a single layer 2 switch that can switch layer 2 packets,
learn and filter on media access control (MAC) addresses, and flood packets that have
unknown MAC destination addresses (DAs).
VPLS Edge Devices
In a VPLS configuration, E Series PE routers host VPLS edge (VE) devices, which are also
referred to as VE routers or, simply, VEs. A VE device is a VPLS instance that services a
particular customer site.
Figure 128 on page 574depicts two PE routers: PE 1, which is the local router, and PE 2,
which is the remote router located at the other side of the service provider core. Each PE
router must have a VPLS instance—the VE device—configured for each VPLS domain in
which it participates. Consequently, the sample topology comprises a total of four
separate VPLS instances: instances vplsA and vplsB configured on PE 1, and instances
vplsA and vplsB configured with matching route target values on PE 2.
Each VPLS instance configured on the router is associated with two types of interfaces,
also known as ports. The CE-facing interface is an Ethernet or bridged Ethernet network
interface that directly connects the PE router to each CE device. The VPLS virtual core
interface, although not an actual physical interface, is automatically generated by the
router for each VPLS instance and represents all of the MPLS tunnels from the router to
the remote PE devices. The router encapsulates Ethernet frames from the CE device in
an MPLS packet and then forwards the encapsulated frames to the service provider core
through the provider (P) router. This encapsulation is identical to Martini encapsulation
for Ethernet layer 2 services over MPLS.
575 Copyright © 2010, Juniper Networks, Inc.
Chapter 11: VPLS Overview