Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 317)

Multi-Service IronWare Switching Configuration Guide 287
53-1003036-02
Backbone Edge Bridge (BEB) operation
11
FIGURE 48 Unknown Destination PBB Packet Handling
If the PBB packet received was for an ISID that the BEB does not care about (no SI configured that
matches the B-VLAN and ISID value of the PBB packet), then the packet is forwarded based on the
B-Tag and the B-MACs as a regular Layer 2 packet. No attempt will be made to look into the inner
MAC of the PBB packet.
NOTE
No validation is made between the 3-byte I-SID value within the default B-DA multicast address to
the PBB header's ISID value. Brocade NetIron XMR and Brocade MLX series will always use the PBB
header ISID value when a switching decision is made.
Known Destination PBB Packet handling
When ingress BEB receives a packet with known C-DA that it learnt from one of the IB-endpoint, it
will forward the received packet towards the IB-endpoint that it learnt the C-DA. The PBB header will
contain the B-VID and ISID that correspond to what was configured for the corresponding SI. The
B-DA will be the B-MAC associated with the learnt C-DA. The B-SA will be set to the chassis base
MAC address.
Unknown Destination PB packet Handling
When a packet is received at a local endpoint (S/C-Tagged or Port based untagged), if the C-DA is
unknown, it will also require flooding of this packet towards all local endpoints as well as towards
the PBB network via the IB-endpoints.
If a flooding B-DA was configured for this SI, when it floods the packet to the IB-endpoints, it will use
the configured flooding B-DA. Otherwise, it will use the default backbone multicast destination MAC
address when it floods the packet towards the PBB network.
BEB Acting as BCB
When a BEB receives a PBB packet with the B-DA and it is not its own chassis MAC, then the packet
must be destined for some other PBB node within the PBB network. In this case, the BEB will act as
a BCB and Layer 2 switch the received packet based on the B-MACs and the B-VLAN towards the
next PBB node. The ISID portion of the packet is ignored and treated as part of the payload.
PBB MAC Learning
With the introduction of PBB, there will be some MAC interactions for the B-MACs involved between
Layer 2 (for B-VLAN) and PBB.