Quiz 4 Key CNT 5106C 1 March 2011 1. a) What is the difference between routing and forwarding? b) What is the relationship between routing and forwarding? 2. a) How do virtual circuit (VC) networks differ from datagram networks? b) How do VC network deal with the problem that the same VC identifier might be assigned to two different VCs? Explain. KEY 1. a) Routing is the process of determining the path a packet will take to reach its destination(s), whereas forwarding is the process of determining on which output port to queue a packet on a router. b) Routing is used to set the forwarding tables used by forwarding. 2. a) In VC networks, the entire path for transmission from source to destination is set up before data begins to flow along that path. The set-up phase determines the path and stores state information at the routers along the path that allows them to forward packets quickly. Packets need not contain the destination or source address, only a VC identifier, as source and
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