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Shortest path bridging

(also SPB)

Shortest path bridging definition

Shortest path bridging (SPB), defined in the IEEE 802.1aq standard, is an advanced network technology used for simplifying the creation and configuration of complex network topologies. It's particularly useful in large-scale networks like data centers or metropolitan area networks.

SPB’s main goal is to optimize the paths that data packets take across a network. While in traditional networks creating multiple paths for data can be complex and prone to errors, SPB simplifies everything by automatically calculating the shortest and most efficient paths.

See also: data link layer definition, reverse-path forwarding, pathname

How SPB works

  • Path calculation. Each switch in the network is aware of the entire network's topology because of the link-state protocol. The switches use algorithms (for example, Dijkstra's algorithm) to calculate the shortest path through the network to every other switch.
  • Using multiple paths. Unlike traditional spanning tree protocols, SPB allows the use of all available paths in the network. This means that data packets have multiple routes they can take to reach their destination. It optimizes network traffic and reduces bottlenecks.
  • MAC-in-MAC encapsulation. SPB uses a technique called MAC-in-MAC encapsulation to improve scalability. This method helps manage the network's addressing more efficiently.