Overview of BGP specification

BGP is a distance-vector routing protocol, which advertises its routing table periodically. These updates will include networks advertised, attributes used that influence the path of the packet, the next hop address that allows us to reach the destination network, and the AS through which the route update has passed.

BGP uses a list of AS to try to ensure a loop-free path by enforcing a rule that no AS path may contain the same AS number twice. The following characteristics of BGP will allow it to create summaries of networks to reduce the size of the routing tables:

  • BGP uses lots of attributes to choose the best path to a destination network. If multiple AS numbers are used, BGP also takes this into consideration ...

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