transit service
In BGP, the function provided by an autonomous system that is in the path of a route but not the origination or destination. To provide reliable transit service, an autonomous system must ensure that its BGP and non-BGP routers agree on the interior routes and exit and entry points for each transit route through the autonomous system. The PortMaster synchronizes routing information between the BGP and non-BGP routers within its autonomous system by means of the lockstep feature. See also lockstep.