VC

Virtual Circuits

"Source-to-Destination path behaves much like telephone circuit"

performance-wise

network actions along source-to-destination path

call setup for each call before data can flow

each packet carries VC identifier (not destination host address)

every router on source-destination path maintains "state" for each passing connection

link, router resources (bandwidth, buffers) may be alocated to VC (dedicated resources = predictable service)

Implementation

1. path from source to destination

2. VC numbers, one number for each link along path

3. entries in forwarding tables in routers along path

packet belonging to VC carries VC number (rather than destination address)

VC number can be changed on each link.