Archive for August, 2015

BGP loop prevention

Written by admin. Posted in BGP

BGP loop prevention

When BGP updates travel through different Autonomous Systems (AS), EBGP routers prepend their AS to AS PATH attribute.  BGP routers use this information to check through which Autonomous Systems certain updates passed. If a EBGP speaking router detects its own AS in AS PATH attribute update, the router will ignore the update and will not advertise it further to IBGP neighbors, because it is a routing information loop. This is a built in mechanism for loop prevention in BGP.

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