Packet Switching Datagram packet switching Route chosen on packet-by-packet basis Different packets may follow different routes Packets may arrive out of order at the destination E.g., IP(The Internet Protocol Virtual Circuit packet switching All packets associated with a session follow the same path Route is chosen at start of session Packets are labeled with a vc# designating the route The vc number must be unique on a given link but can change from link to link Imagine having to set up connections between 1000 nodes in a mesh Unique Vc numbers imply 1 Million vc numbers that must be represented and stored at each node E.g., ATM(Asynchronous transfer mode)Eytan Modiano Slide 14 Packet Switching • Datagram packet switching – Route chosen on packet-by-packet basis – Different packets may follow different routes – Packets may arrive out of order at the destination – E.g., IP (The Internet Protocol) • Virtual Circuit packet switching – All packets associated with a session follow the same path – Route is chosen at start of session – Packets are labeled with a VC# designating the route – The VC number must be unique on a given link but can change from link to link Imagine having to set up connections between 1000 nodes in a mesh Unique VC numbers imply 1 Million VC numbers that must be represented and stored at each node – E.g., ATM (Asynchronous transfer mode)