Answer the following problems.
problem 1) A network uses routers with fair queueing. This is not weighted - all weights are the same.
(a) Two connections share same congested gateway and have no other congested gateways. Connection A has RTT 5ms, connection B has RTT 10ms. State the throughput of connection B(tputB) in terms of throughput achieved by connection A ( tputA), or specify if there is no relationship between the two.
(b) Two connections traverse same congested gateway, but also traverse some other unshared congested gateways. State the throughput of connection B (tputB) in terms of throughput achieved by connection A ( tputA), or specify if there is no relationship between the two.
problem 2) Matt thinks that fair queuing is great idea! Every flow gets fair share of bandwidth. He is sad to determine it is not extensively implemented. Why is not fair queuing used across the entire Internet?
problem 3) In link state routing protocols, routers broadcast link state announcements to rest of the network containing information about which routers they are directly connected to. Each router collects these announcements from every other router and uses them to build a graph of the network.
(a) Routers store these link state announcements with time to live (TTL); an announcement is deleted when
1) a more recent announcement from same router arrives and replaces it or
2) the TTL expires. Why is this TTL timeout essential?
(b) Link state announcements have sequence numbers to make sure that router never replaces newer information with stale information from older message still circulating in the network. Unlike other protocols, these sequence numbers are not expected to wrap around (and so they should be fairly long, like, 64 bits). A problem can arise when the router crashes, reboots, and begins sending link state announcements starting at sequence # 0. How does network deal with this situation (suppose that routers don’t store current sequence number in non-volatile storage so that it is available after a reboot)?