EC312 Homework 27
Name: ____SOLUTIONS_______________
1.
Given the following ARP table, make the necessary change(s) to cause all Ethernet traffic destined for
192.168.14.10 to flow to you (192.168.14.13) instead?
IP
192.168.14.8
192.168.14.9
192.168.14.10
192.168.14.12
192.168.14.13
192.168.14.21
192.168.14.25
2.
MAC
AA:BB:CC:DD:EE:FF
AA:BB:AA:BB:AA:BB
A4:B5:C6:D7:E8:F9
EE:FF: EE:FF:EE:FF
A4:B5:C6:D7:E8:F9
C6:D7:C6:D7:C6:D7
E8:F9: E8:F9:E8:F9
Why is the destination hardware address all 0s in the ARP request message?
Because when a request is made, the sender does not know the destinations hardware address
yet. This destination hardware address of all 0s is part of the ARP request packet. It should not
be confused with the datalink layer Ethernet frame which has a destination hardware address of
all fs (broadcast address).
3.
Why is the destination hardware address of the frame from A to B a broadcast address?
The frame uses a broadcast address so that the intended recipient on the network will receive the
frame even though the sender does not know the specific hardware address of the intended
recipient.
4. To acquire an IP address, the sourec address is 0.0.0.0 and the destination address is 255.255.255.255.
5.
Combine the following three blocks of addresses into a single block:
a. 16.27.24.0/26 - 00010000.00011011.00011000.00|000000
Range – 16.27.24.0 to 16.27.24.63
b. 16.27.24.64/26 - 00010000.00011011.00011000.01|000000
Range – 16.27.24.64 to 16.27.24.127
c. 16.27.24.128/25 - 00010000.00011011.00011000.1|0000000
Range – 16.27.24.128 to 16.27.24.255
Total Range - 16.27.24.0 to 16.27.24.255
Combined: 16.27.24.0/24
hing
hing
Can router R1 in figure below receive a packet with destination address 140.24.7.194?
hing6.What will
happen to the packet if this occurs?
Figure 22.8 Longest mask matching
It can receive a packet with a destination address 140.24.7.194 from Organization 1, 2, or 3. It
will route the packet through interface, m3, to router R2.
7.
Assume router R2 above has fixed its routing table to have longest mask matching below, and it receives
k
k matching
matching
a packet with destination address 140.24.7.42. How is the packet routed to its final destination?
18
Router R2 will compare the destination address with its forwarding table. Using the mask, R2
determines if the destination address is part of the 140.24.7.192 network. It is not. R2 compares
the destination address with the 140.24.7.0 network. It is part of this network. R2 will forward
the packet to R1 via interface m0. When R1 receives the packet, it will use its forwarding table
similar to R2, starting at the top and working its way down. In this case, the packet is destined
for an IP address that is part of the network 140.24.7.0. R1 will send to packet to the appropriate
host in Organization 1 via interface m0.
8.
Construct the routing table for router RB in the picture shown below.
Network address/mask
2.2.2.4/30
4.4.4.40/29
3.3.3.32/27
0.0.0.0/0
Next-hop address
------------default router
Interface
m0
m1
m2
(none given in
this problem)