Brocade Communications Systems IP250 user manual 883

Virtual Private LAN Services (VPLS) overview 28

CE Device

Customer A

R2

R1	R3
CE Device
Customer A	MPLS Domain

	R4
100	Customer B	200
VLAN		VLAN
	CE Devices

CE Devices

Customer A

Customer B

VLAN 100 VLAN 200

FIGURE 359 VPLS configuration with two customer VPNs

Unlike a Virtual Leased Line (VLL), a VPLS instance can have multiple endpoints. The PE device performs local and remote VLAN tag translation, so that multiple VLANs can be specified under a single VPLS instance. A VPLS instance consists of a full mesh of VC LSPs between the customer’s Provider Edge (PE) devices. The full mesh of PE devices in a VPLS configuration allows one PE device to reach any other PE device in the VPN in exactly one hop, with no transit PE devices in between.

A PE device performs MAC address learning, flooding, and forwarding for the CE devices in each VPLS instance. For example, when PE device R1 receives a Layer 2 frame with a given MAC destination address from Customer A’s CE device, it looks up the MAC address in a Layer 2 forwarding table that records associations between MAC addresses and VC LSPs. This forwarding table is known as the VPLS MAC database.

The PE device uses MAC address found in the VPLS MAC database to find the associated VC LSP. The PE device then encapsulates the frame as an MPLS packet and pushes an inner VC label and outer tunnel label onto the packet. The packet is then sent over a tunnel LSP to the VC peer.

Brocade Network Advisor IP User Manual	883
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