Figure 37: Access Port Egress Packet Format And Lookup; Virtual Private Lan Service - Alcatel-Lucent 7750 SR OS Service Manual

Service router - mobile gateway

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Table of Contents

2. Core Router Switching

a. All the core routers ('P' routers in IETF nomenclature) between PE-Router-A and PE-Rout-

3. PE-Router-C

a. PE-Router-C strips the transport label of the received packet to reveal the inner VC-label.

b. PE-Router-C learns the source MAC address in the packet and creates an entry in the FIB

c. The destination MAC address in the packet is looked up in the FIB table for the VPLS in-

d. If the destination MAC address has been learned by PE-Router-C, an existing entry in the

7750 SR OS Services Guide

er-B and PE-Router-C are Label Switch Routers (LSRs) that switch the packet based on the

transport (outer) label of the packet until the packet arrives at far-end PE-Router. All core

routers are unaware that this traffic is associated with a VPLS service.

The VC-label identifies the VPLS service instance to which the packet belongs.

table that associates the MAC address to PE-Router-A and the VC-label that PE-Router-A

signaled it for the VPLS service.

stance. Again, there are two possibilities: either the destination MAC address has already

been learned (known MAC address) or the destination MAC address has not been learned

on the access side of PE-Router-C (unknown MAC address).

Known MAC address

FIB table identifies the local access port and the IEEE 802.1Q tag to be added before send-

ing the packet to customer Location-C. The egress Q tag may be different than the ingress

Pre-assigned and

signaled by PE 'C'

Apply VC and

Tunnel Labels

Pre-assigned and

signaled by PE 'B'

Figure 5: Access Port Egress Packet Format and Lookup

IP/MPLS NETWORK

Virtual Private LAN Services