PBB Features
Page 794 7750 SR OS Services Guide
PBB Blackholing Issue
In the PBB VPLS solution, a B-VPLS may be used as infrastructure for one or more I-VPLS
instances. B-VPLS control plane (LDP Signaling or P-MSTP) replaces I-VPLS control plane
throughout the core. This is raising an additional challenge related to blackhole avoidance in the I-
VPLS domain as described in this section. Figure 112 describes the case of a QinQ switch (node 5)
dual-homed through MC-LAG to two I-VPLS instances located on PBB PEs A1 and A2.
Figure 112: PBB Blackholing - MC LAG example
Assuming that the link between PE A1 and node 5 is active, the remote PEs participating in the
orange VPN (for example, PE D) will learn the CMAC X associated with backbone MAC A1.
Under failure of the link between node 5 and PE A1 and activation of link to PE A2, the remote
PEs (for example, PE D) will black-hole the traffic destined for customer MAC X to BMAC A1
until the aging timer expires or a packet flows from X to Y through the PE A2. This may take a
long time (default aging timer is 5 minutes) and may affect a large number of flows across multiple
I-VPLSes.
A similar issue will occur in the case where node 5 is connected to A1 and A2 I-VPLS using
active/standby pseudowires. For example, when node 5 changes the active pseudowire, the remote
PBB PE will keep sending to the old PBB PE.
To Next Page
Loading...
