Alcatel-Lucent 7210 SAS M - Dual Homing to a VPLS Service; Figure 46: Dual Homed CE Connection to VPLS

Virtual Private LAN Services
7210 SAS M Services Guide Page 283
Dual Homing to a VPLS Service
Figure 46: Dual Homed CE Connection to VPLS
Figure 46 illustrates a dual-homed connection to VPLS service (PE-A, PE-B, PE-C, PE-D) and
operation in case of link failure (between PE-C and L2-B). Upon detection of a link failure PE-C
will send MAC-Address-Withdraw messages, which will indicate to all LDP peers that they
should flush all MAC addresses learned from PE-C. This will lead that to a broadcasting of
packets addressing affected hosts and re-learning process in case an alternative route exists.
Note that the message described here is different than the message described in draft-ietf-l2vpn-
vpls-ldp-xx.txt, Virtual Private LAN Services over MPLS. The difference is in the interpretation
and action performed in the receiving PE. According the draft definition, upon receipt of a MAC-
withdraw message, all MAC addresses, except the ones learned from the source PE, are flushed,
This section specifies that all MAC addresses learned from the source are flushed. This message
has been implemented as an LDP address message with vendor-specific type, length, value (TLV),
and is called the flush-all-from-ME message.
L2-A
PE-A
PE-B
L2-B
PE-C
PE-D
MAC flush
Link down
OSSG117
L2-A
PE-A
PE-B
L2-B
PE-C
PE-D
L2-A
PE-A
PE-B
L2-B
PE-C
PE-D
L2-A
PE-A
PE-B
L2-B
PE-C
PE-D