DestinationAddress Output port number or VC number A packet switch consists of a routing engine (table look-up), a switch scheduler, and a switch fabric
Service times M/G/1 General independent Poisson arrivals at rate λ Service time has arbitrary distribution with given E[X] and E[X2] – Service times are independent and identically
Carrier Sense Multiple Access (CSMA) In certain situations nodes can hear each other by listening to the channel “Carrier Sensing” CSMA: Polite version of Aloha
Broadcast Routing Route a packet from a source to all nodes in the network Possible solutions: – Flooding: Each node sends packet on all outgoing links Discard packets received a second time – Spanning Tree Routing: Send packet along a tree that includes all of the nodes in the network
Routing Must choose routes for various origin destination pairs (O/D pairs) or for various sessions – Datagram routing: route chosen on a packet by packet basis Using datagram routing is an easy way to split paths – Virtual circuit routing: route chosen a session by session basis