$6\mathrm{.}4-10$ Network$-$ and Link$-$layer addressing: an end$-$to$-$end$-$scenario $(3$a$).$ Consider the network shown below. The IP and MAC addresses are shown for hosts A$,$ B$,$ C

and $D,$ as well as for the router's interfaces. Consider an IP datagram being sent from node $C$ to node $A($note: from right to left$).$ Match the source$/$destination network$-$ or

link$-$layer address at the location $(1)$ by choosing a value from the pulldown list. $[$Note: You can find more examples of problems similar to this here.$]$

What is the source MAC address on the frame at point $(1)?$

What is the destination MAC address on the frame at point $(1)?$

What is the source IP address of the datagram at point $(1)?$

$W$ What is the destination IP address of the datagram at point $(1)?$

$128\mathrm{.}119\mathrm{.}240\mathrm{.}52$

The MAC address of the switch immediately left of location $(1).$

CC$-$A$5-81-0$B$-$AE$-33$

$128\mathrm{.}119\mathrm{.}97\mathrm{.}194$

$128\mathrm{.}119\mathrm{.}240\mathrm{.}15$

$72-9E-4A-31-9C-42$

$128\mathrm{.}119\mathrm{.}97\mathrm{.}18$

$4$C$-9$D$-$AA$-74-$D$6-1$F

a $77-34-$F$1-$EF$-14-72$

$6\mathrm{.}3$A$-4.$ Multiple Access protocols $(4).$ Consider the figure below, which shows the arrival of $6$ messages for transmission at different multiple access wireless nodes at times

$t=0\mathrm{.}1,1\mathrm{.}4,1\mathrm{.}8,3\mathrm{.}2,3\mathrm{.}3,4\mathrm{.}1.$ Each transmission requires exactly one time unit.

$t$

For the CSMA$/$CD protocol $($with collision detection$),$ indicate which packets are successfully transmitted. You should assume that it takes $.2$ time units for a signal to

propagate from one node to each of the other nodes. You can assume that if a packet experiences a collision or senses the channel busy and that that node will not attempt a

retransmission of that packet until sometime after $t=5.$ If a node senses a collision, it stops transmitting immediately $($although it will still take $.2$ time units for the last

transmitted bit to propagate to all other nodes$).$ Hint: consider propagation times carefully here. $[$Note: You can find more examples of problems similar to this here.$]$

$1$

$2$

$3$

$4$

$5$

$6$

$6\mathrm{.}4-6.$ Self Learning Switches $($c$).$ Consider the network below with six nodes, star$-$connected into an Ethernet switch. Suppose that A sends a frame to A$,$ A$\text{'}$ replies to A$,$

then B sends a message to $B^{\text{'}}$ and $B^{\text{'}}$ replies to $B,$ and then A sends to $B$ and $B$ replies to $A.$ In this sequence of frame transmissions, how many frames have appeared at the

interface at C$\text{'}?$ Assume that the switch's table is initially empty. $[$Note: You can find more examples of problems similar to this here.$]$

None of these frames appear at $C\text{'}$s interface, since none of the fames were addressed to $C\text{'}.$

Two frames appear at the $C^{\text{'}}$ interface.

Five frames appear at the $C^{\text{'}}$ interface.

Six frames appear at the $C^{\text{'}}$ interface.

Three frames appear at the $C^{\text{'}}$ interface.