Pe Dual Homing - HP 10500 Series Configuration Manual

After a PE receives a unicast packet from a PW, the PE searches the MAC address table of the VSI bound
to the PW to determine how to forward this packet.
• If a match is found, the PE forwards the packet according to the matching entry. If the outgoing
interface in the entry is a local interface, the PE directly forwards the packet to the local interface.
If no match is found, the PE floods the packet to all ACs in the VSI.
•
Multicast and broadcast traffic forwarding and flooding:
After a PE receives a multicast or broadcast packet from an AC, the PE floods the packet to all other ACs
and the PWs in the VSI bound to the AC.
After a PE receives a multicast or broadcast packet from a PW, the PE floods the packet to all ACs in the
VSI bound to the PW.
PW full mesh and split horizon
A loop prevention protocol such as STP is required in a Layer 2 network to avoid loops. However,
deploying a loop prevention protocol on PEs brings management and maintenance difficulties. Therefore,
VPLS uses the following methods to prevent loops:
• Full mesh—Every two PEs in a VPLS instance must establish a PW to create a full mesh of PWs
among PEs in the VPLS instance.
Split horizon—A PE does not forward packets received from a PW to any other PW in the same VSI
•
but only forwards those packets to ACs.

PE dual homing

If only one PW is available between two CEs, the CEs cannot reach each other when the PW fails.
PW dual homing provides two PWs between CEs, as shown in
each other through the primary PW. When the primary PW fails, PE 1 uses the backup PW to forward
packets from CE 1 to CE 2. After CE 2 receives the packets from CE 1, CE 2 updates the MAC entry so
the packets from CE 2 to CE 1 are also forwarded through the backup PW.
Figure
267
73. The CEs communicate with