H3C Technologies H3C S12500 Series Switches - Manual (Page 9)

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SPBM overview
IEEE 802.1aq Shortest Path Bridging (SPB) enables multipath routing in an Ethernet mesh network by
using IS-IS as the control protocol. The technology allows all paths to be active, supports equal cost paths,
and provides shortest path forwarding in an Ethernet mesh network. IEEE 802.1aq SPB provides faster
convergence, higher link efficiency, and larger Layer 2 topologies than conventional spanning tree
protocols such as MSTP.
Shortest path bridging MAC mode (SPBM) is one bridging method of IEEE 802.1aq SPB. This method
encapsulates Ethernet frames into MAC-in-MAC frames in compliance with IEEE 802.1ah PBB.
SPBM network model
As shown in Figure 1 , the SPBM network includes backbone edge bridges and backbone core bridges.
Backbone edge bridges connect customer sites to the SPBM network.
The nodes in the SPBM network run ISIS-SPB to prevent loops and calculate the shortest path for a frame.
Figure 1 SPBM network model
Terminology
Area
An SPBM area is a subdomain of an SPBM network. The device supports only one area.
Customer
site
Customer
site
Customer
site
Customer
site
SPBM
network
BCB BCB
BCB BCB
BEB BEB
BEB BEB