CS Summer 2003 Quiz 1 A1) IGP (IS-IS, OSPF) BGP A2) Stub Transit. because it is adverting AS2’s routes to AS1 and vice versa. A3) Traffic discarded (black-holed). No. Because it is a static route. A4) Traffic discarded (black-holed) until an alternate path is found. Yes. Because it is learned via dynamic routing (IGP).

CS Summer 2003 Quiz 1 A5) A) Link state protocol Vs Path Vector B) OSPF computes path using SPF algorithm. BGP has a complete route and selects the best route through decision process. C) BGP supports effective mechanism to enforce policies. More …. D) Enterprise level Vs Global etc. A6) A) Route aggregation B) Scalability(route aggregation reduces table entries) A7) A) Yes. Because BGP session is based on TCP and BGP peer must be reachable to establish session. B) BGP session will terminate after sometime. C) KeepAlive

CS Summer 2003 Quiz 1 A8) A) via Update message B) No. Because all path attributes must be associated with all NLRIs (prefixes) and that defines a route. C) Yes. No such restriction when withdrawing routes. A9) A) Loop prevention, policy enforcement, and influencing the traffic flow. B) Yes. Recall AS_PATH attribute, Origin, Local_PREF, MED. A10) A) AS_PATH B) Inset Dummy AS 100 to make the AS_PATH length bigger on the existing traffic path and causing the traffic to flow along the desired path.