SPB brings a link state capability that improves the scalability and performance for large networks over the xSTP flooding and learning models. Flooding and learning has two consequences. First, a message invoking a flush must be propagated, second the data plane is allowed to flood and relearn while flushing is happening. Message based operation over these data planes may experience congestion and packet loss.
| PBB B-VPLS Control plane |
Flooding and learning | Multipath | Convergence time |
|---|---|---|---|
xSTP |
Yes |
MSTP |
xSTP + MMRP |
G.8032 |
Yes |
Multiple Ring instances Ring topologies only |
Eth-OAM based + MMRP |
SPB-M |
No |
Yes –ECT based |
IS-IS link state (incremental) |
Link state operates differently in that only the information that truly changes needs to be updated. Traffic that is not affected by a topology change does not have to be disturbed and does not experience congestion because there is no flooding. SPB is a link state mechanism that uses restoration to reestablish the paths affected by topology change. It is more deterministic and reliable than RSTP and MMRP mechanisms. SPB can handle any number of topology changes and as long as the network has some connectivity, SPB does not isolate any traffic.