Formation And Maintenance Of Isis-Spb Adjacencies; Mac Address Learning; Data Paths - H3C S12500 Series Configuration Manual

a. Each node runs SPF to calculate the shortest path from itself to each of the other nodes.
b. If equal-cost paths are available, each node runs ECT to choose the best forwarding path.
c. The nodes populate their respective FDB and FIB tables with the forwarding path.
4. BEBs establish PWs over the SPBM network for transmitting customer traffic.

Formation and maintenance of ISIS-SPB adjacencies

ISIS-SPB only supports point-to-point links within an IS-IS level 1. It sends P2P hellos between directly
connected nodes to form and maintain adjacencies. To forward traffic on an adjacency, two SPBM
neighbors must meet the following requirements:
The neighbors have the same configuration digest for MSTI 4092.
•
The neighbors have the same B-VLAN to ECT algorithm mapping.
•
The neighbors have valid link metric values.
•

MAC address learning

In an SPBM network, BEBs perform typical source MAC learning in the data plane to learn C-MACs, but
BCBs do not learn C-MACs.
BCBs forward MAC-in-MAC traffic by destination B-MAC and B-VLAN, which are advertised through
ISIS-SPB in the control plane. As a result, BCBs do not need to maintain a large MAC address table.

Data paths

For the forwarding process for known unicast frames, see "Unicast."
To avoid loops, SPBM does not support broadcast. BEBs flood broadcast, unknown unicast, and
unknown multicast frames to the SPBM network as multicast frames. For the flooding process, see
"Multicast."
Unicast
For an intra-site known unicast frame, the ingress BEB performs typical MAC address table lookup.
For a known inter-site unicast frame, the following forwarding process takes place, as shown in
1. The ingress BEB performs the following tasks:
a. Assigns the frame to the correct Ethernet service instance based on the outer VLAN.
b. Learns the source MAC address.
c. Looks up the destination MAC address in the Ethernet service instance's Ethernet address table.
2. If the outgoing interface is a provider network port, the ingress BEB performs the following tasks:
a. Encapsulates the frame in IEEE 802.1ah format.
b. Sends the frame out of the unicast PW to the egress BEB.
The B-DA field in the outer frame header is the B-MAC of the egress BEB.
3. Each BCB on the unicast PW forwards the frame based on the B-MAC and B-VLAN in the outer
frame header until it reaches the egress BEB.
4. The egress BEB removes the outer frame header and forwards the frame to the destination
customer MAC address.
5
Figure 3: