In this question we consider some of the pros and cons of vi

In this question, we consider some of the pros and cons of virtual-circuit and datagram networks.

Suppose that routers are subjected to conditions that might cause them to fail fairly often. Would this argue in favor of a VC or datagram architecture? Why?

Support that a source node and a destination require that a fixed amount of capacity always be available at all routers on the path between the source and destination node, for the exclusive use of traffic flowing between this source and destination node. Would this argue in favor of a VC or datagram architecture? Why?

Support that the links and routers in the network never fail and that routing paths used between all source/destination pairs remains constant. In this scenario, does a VC or datagram architecture have more control traffic overhead? Why?

Solution

Datagram:

                   If the network is connection based network when the router gets any problems its all because of the

connection that is established in the router.

                            By keeping connection less datagram network there is no need of signal to set up a new

downstream path or take down the old downstream path. The routing tables will need to be updated (e.g., either via

a distance vector algorithm or a link state algorithm) to take the failed router into account. We have seen that with

distance vector algorithms be localized to the area near the failed router. So that is datagram networks is chosen.

VC: It need to know the characteristics of the traffic from all sessions passing through that link. So the router must

have per-session state in the router. It’s possible to be achieved in connection oriented network, but impossible in

connectionless network. So VC would be better.

Datagram architecture would have much better control ability. VCwill never change after a certain connection has

been set up. But datagram’s can determine the next hop based on the packet headers. So it’s obviously that

datagram has more control traffic overhead.