Juniper JUNOSE, Configuration Manual

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Figure 128 on page 570depicts 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 570 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 570depicts 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.
Each PE router in the sample topology has a total of two network interfaces and two
VPLS virtual core interfaces configured, one interface of each type per VPLS instance.
VPLS and Transparent Bridging
A single VPLS instance is analogous to a distributed learning bridge (also known as
a bridge group) used for transparent bridging, and performs similar functions. In
VPLS and Transparent Bridging
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Chapter 9: VPLS Overview