COIT20261 Network Routing and Switching Term 1, 2019

COIT20261 Network Routing and Switching Term 1, 2019
Assignment item —Written Assessment-2
ANSWER TEMPLATE ASSIGNMENT TWO
Type your answers in the spaces provided
Marking criteria:
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Questions Mark
allocated
Mark
earned
Question 1: (10 marks) 5 each table
Answer: Routing table of router R2:
Mask Network address Next-hop address Interface
/24 220.10.40.0 150.3.0.3 M0
/24 200.11.60.0 ----------- M1
/22 140.21.0.0 ----------- M2
/18 161.22.0.0 150.3.0.3 M0
/18 150.32.0.0 150.3.0.1 M0
/16 150.3.0.0 ---------- M0
/0 0.0.0.0 150.3.0.4 M0
Routing table of router R3:
Mask Network address Next-hop address Interface
/24 220.10.40.0 ------------- M1
/24 200.11.60.0 150.3.0.2 M0
/22 140.21.0.0 150.3.0.2 M0
/18 161.22.0.0 ----------- M2
/18 150.32.0.0 15.3.0.1 M0
/16 150.3.0.0 --------- M0
/0 0.0.0.0 150.3.0.4 M0
5 max
5 max
Question 2: (5 marks)
a) The forwarding of the frame or IP routing is determined by the
network protocol used thus deciding on the desired channel of which
1 max

the packet will pass through from the source peer to the end (Cohe,
Postel, & Rom, 2010). In this case what R1 that is regarded the host
mainly does is that it generates a frame that consists of layers that is
one and two and the data itself.
b) Since R4 is directly connected to a software utility known as ping then
it does not differ the transport protocol to exchange data between the
networks. It is well known as the message protocol used for the ping
command. The R4 (largest host) will receive an ICMP request from the
R1 ping. R4 then replies with an echo request to the target R1. In both
movement is consisting of three ip header. Upper layer to whom the
payload is delivered i.e. ICMP, UDP, TCP, Source IP address, and
destination ip address (Jinhua, & Kejian, 2013).
R4 puts destination address in the packet header and then releases it to
the router. The router searches for the destination; this is posted on the
routing table then the packet is transmitted to the next hop towards the
destination. Upon addressing of the network to determine whether the
host is a local or remote destination the ICMP uses the host router to
transfer information such as the unreached host, ports, echo request or
reply(by ping); this are error messages. A series of UDP packets are
sent by the source. The first three packets have TTL set to 1, spaced 3
secs apart, next 3 packets have TLL set to 2. Then the packets are sent
to unused port number. When packet TTL expires, the router
terminates and it is sent to retrieve an ICMP message from it source
(type 1, code 0). When ICMP message arrives back at the R4. R4
calculates round trip time (RTT). UDP packets finally reach the
destination host. The destination replies an ICMP destination port echo
reply (ping) then the packet is sent
2 max
c)
R3has the data that needs to be conveyed across the network and to the
destination that is the remote server. It also has the ip address of the
remote server so R3created an L3 header that basically consists a few
pieces of information, mainly, the Source ip address (SRC) and
2 max

150.32.48.15 which id the Destination ip address and the destination IP
address (DST) which in this case is the remote server. R3then
compares the on its network, the Destination IP address so as to
determine that it’s a full network. R3will then create a layer 2 to take
the packet to the router and since it doesn’t have the mac address it will
need to use the ARP to discover its default gateway’s Mac address.
The host then sends the ARP request 150.32.48.15.to the router. ARP
request is a frame that literally asks if the ip address is there then to
send for the mac address. First of all the thing the switch will do is
basically to learn the address and therefore broadcast the ARP request
to the entire network and both the router and the Human Resource pc
will receive the request and since the Human Resource Machine
doesn’t have the response to the request it will discard it. The router on
the other hand generates the response. The switch receives the response
and automatically learns the mac address of the respondent which was
receive on one of the port which was connected to the router, then
thereafter forwards a response to the host which in this case is R3. This
entire time the data was held by the host while waiting for the address
resolution to be process to complete (Sohn, Moon, Lee, Lee, & Lim,
2013).
Now that R3 has the Mac Address; thus it is able to finally send the
date to the remote server. The host creates an L2 header that sends the
packet. L2 contains the router’s Source ip address and the destination
ip address. L3 contains Source ip address and the destination ip address
of the remote server. L3’s main work is to send data from the sender to
the receiver while L2 basically gets the data from hop to hop within the
network. With this being said the packet is sent on its way. The frame
arrives on the switch which already has the entry Mac address table on
that port. The switch then forwards the frame to the Ethernet connected
to the router. The frame is received by the router on the other end, then
with draws the L2. The frame is made up of the data, L3 and L2 and
since L2 basically consist of hops from the R3to the router it’s
withdrawn. The router then looks at the destination which in this case