Alcatel-Lucent 7750 SR Manual page 800

PBB Features
ES1 and ES2 are dual-homed using MC-LAG into two BEB devices: ES1 to BEB C and BEB D,
ES2 to BEB A and BEB B. MC-LAG P11 on BEB C and P9 on BEB A are active on each side.
In the service context, the yellow triangles are I-VPLS instances while the green circles are B-
VPLS components with the related, per BVPLS source BMACs indicated next to each BVPLS
instances. P-MSTP or RSTP may be used for loop avoidance in the multi-point BVPLS. For
simplicity, only the active SAPs (BEB P2, P4, P6 and P8) are shown in the diagram.
In addition to the source BMAC associated with each BVPLS, there is an additional BMAC
associated with each MC-LAG supporting multi-homed I-VPLS SAPs. The BEBs that are in a
multi-homed MC-LAG configuration share a common B-MAC on the related MC-LAG
interfaces. For example, a common BMAC C1 is associated in this example with ports P11 and
P12 participating in the MC-LAG between BEB C and BEB D while BMAC A1 is associated with
ports P9 and P10 in the MC-LAG between BEB A and BEB B. While BMAC C1 is associated
through the I-VPLS SAPs with both BVPLS instances in BEB C and BEB D, it is actively used for
forwarding to I-VPLS SAPs only on BEB C containing the active link P11.
MC-LAG protocol keeps track of which side (port or LAG) is active and which is standby for a
given MC-LAG grouping and activates the standby in case the active one fails. The source BMAC
C1 and A1 are used for PBB encapsulation as traffic arrives at the IVPLS SAPs on P11 and P9
respectively. MAC Learning in the BVPLS instances installs MAC FIB entries in BCB-E and BEB
A as depicted in
Active link (P11) or access node (BEB C) failures are activating through MC-LAG protocol the
standby link (P12) participating in the MC-LAG on the pair MC-LAG device (BEB D).
Figure 116
Page 800
Figure 115.
depicts the case of access link failure.
7750 SR OS Services Guide