$5.$ Suppose a route has built up the routing table shown in the following table.

$\backslash$begin$\{$tabular$\}\{|$l$|$l$|$l$|\}$

$\backslash$hline SubnetNumber & SubnetMask & Next hop $\backslash \backslash$

$\backslash$hline $128\mathrm{.}96\mathrm{.}39\mathrm{.}0$ & $255\mathrm{.}255\mathrm{.}255\mathrm{.}128$ & Interface $0\backslash \backslash$

$\backslash$hline $128\mathrm{.}96\mathrm{.}39\mathrm{.}128$ & $255\mathrm{.}255\mathrm{.}255\mathrm{.}128$ & Interface $1\backslash \backslash$

$\backslash$hline $128\mathrm{.}96\mathrm{.}40\mathrm{.}0$ & $255\mathrm{.}255\mathrm{.}255\mathrm{.}128$ & R$2\backslash \backslash$

$\backslash$hline $192\mathrm{.}4\mathrm{.}153\mathrm{.}0$ & $255\mathrm{.}255\mathrm{.}255\mathrm{.}192$ & R$3\backslash \backslash$

$\backslash$hline Default & & R$4\backslash \backslash$

$\backslash$hline

$\backslash$end$\{$tabular$\}$

The router can deliver packets directly over interfaces $0$ and $1,$ or it can forward packets to routers R$2,$ R$3,$ or R$4.$ Describe what the router does with a packet addressed to each of the following destinations:

$($a$)128\mathrm{.}96\mathrm{.}39\mathrm{.}135$

$($b$)128\mathrm{.}96\mathrm{.}39\mathrm{.}40$

$($c$)128\mathrm{.}96\mathrm{.}40\mathrm{.}150$

$($d$)128\mathrm{.}96\mathrm{.}40\mathrm{.}16$

$($e$)192\mathrm{.}4\mathrm{.}153\mathrm{.}200$

$($f$)192\mathrm{.}4\mathrm{.}153\mathrm{.}32$

Consider the arrangement of learning bridges shown in the following figure. Assuming all

are initially empty, give the forwarding tables for each of the bridges B$1-$B$3$ after the

following transmissions:

$(1)$ A sends to B; $(2)$ B sends to A; $(3)$ A sends to X;

$(4)$ X sends to A; $(5)$ D sends to Y; $(6)$ E sends to D$\_\_$

Using the example network below, give the virtual circuit tables for all the switches after

each of the following connections is established. Assume that the sequence of connections is

cumulative; that is$,$ the first connection is still up when the second connection is established,

and so on$.$ Also assume that the VCI assignment always picks the lowest unused VCI on

each link, starting with $0,$ and that a VCI is consumed for both directions of a virtual circuit.

$($a$)$ Host A connects to host C $.$

$($b$)$ Host D connects to host B $.$

$($c$)$ Host D connects to host I.

$($d$)$ Host A connects to host B$.$

$($e$)$ Host F connects to host J$.$

$($f$)$ Host H connects to host A $.$

Link$-$state routing protocols

This question explores how to set the $($configurable$)$ link weights in link$-$state routing protocols like OSPF inside a single Autonomous System $($AS$)$ to achieve AS$-$wide goals.

a$)$ How should the network operators set the link weights if their goal is to minimize the number of hops each packet traverses to reach its destination?

b$)$ How should the operators set the link weights to minimize the end$-$to$-$end delay the traffic experiences? Assume the network is lightly loaded, so queuing delay is insignificant.

c$)$ In the picture below, the nodes are routers, the edges are links, and the integers correspond to the link weight on each direction of the link. $($That is$,$ the link a $-$ b and the link b $-$a both have weight $10.)$ Put arrows on the edges to show the shortest path from every node to the destination node d$.$ That is$,$ show the "sink tree" leading to node d$.$

d$)$ Suppose the link i$-$h is overloaded with traffic. Identify a single weight change $($on just one link$)$ that would divert traffic from source i$,$ to destination d away from the i$-$h edge without affecting the path between any other source$-$destination pairs. Avoid any reliance on how routers choose between multiple paths with the same $($smallest$)$ cost$.$ Give me answers to all the questions which are attached in images.