CS4461

CS4461 Computer Networks Final Exam Study Guide

Virtual Circuit Networks:

Virtual Circuit networks consist of

   -path between src and dst hosts
   -VC numbers, one number for each link along the path
   -Entries in the forwarding table in each router along the path

Packets carry VC numbers in the header. Each router in the VC must rewrite this header since they may differ depending on the router.

In a Virtual Circuit network the routers must maintain connection state information for the ongoing connections. Each time a new connection is started a new entry in the forwarding table needs to be created.

Virtual Circuit Phases

   -VC setup: the sending transport layer contacts the network layer, specifies the receiver's address, and waits for the network to set up the VC. The network layer determines the path between src and dst that is the series of links and routers through which all packets of the VC will travel. The network layer then adds an entry in the forwarding table in each router along the path.
   -Data Transfer: VC is established and data begins to flow
   -VC teardown: src or dst informs network layer of its desire to terminate the VC. The network layer then updates forwarding tables to delete the routes.