COIT20261 Network Routing and Switching Term 1, 2019

This document is an answer template for Assignment Two of COIT20261 Network Routing and Switching Term 1, 2019. It includes routing tables for routers R2 and R3, explanations of IP routing and forwarding, and information about autonomous systems and routing protocols.

COIT20261 Network Routing and Switching Term 1, 2019
Assignment item —Written Assessment-2
ANSWER TEMPLATE ASSIGNMENT TWO
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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
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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
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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
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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

is the remote server that is connected to the internet.
The router in this part determines the dynamic routing protocol that is
going to uses to convey the frame. Routing protocol determines the
best suitable channels to each network; this is then updated on the
routing table which is on the primary table. This will enable the router
to understand on how to find other paths while it learns about the
network. With comparison of static routing to dynamic routing, it more
monitory by the admin. For this instant, there are 2 separate dynamic
routing routines, name; Link-State-routing and secondly Distance-
Vector-routing; they are advertised as vectors of both direction and
distance. The hope-count, the direction to the next hop router and the
exit interface determine this. It basically uses as a signpost to the next
router. Link-State Routing Protocol on the other hand is able to create
an inclusive view of the network; this is achieve through gathering of
information from all routers (Lee, Gerla, & Chiang, 2010 ). In
contrast to distance vector, this determines on the connectivity of the
network and does not make use of the updates done periodically on the
information from the neighbours. Since the frame needs to reach to the
destination and we basically don’t know which geographical are the
server is locates. The router will be promoted to make use the link-
state-routing protocol which is determined by the strength of the
connectivity of the network.
Question 3: (10 marks)
a) A system that is autonomous is made up of a collection of multiple
networks brought together and they are all overseen from a single unit
or organization. This system has many different subnets that have the
same routing policies and common routing logics.
Each Autonomous system subnetworks are assigned a global unique 16
digit identification numbers that is also known as ASN or the AS
number.
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Autonomous Systems and its relationship to the Border-Gateway
Protocol
It is also known as BGP, it is a network protocol which addresses the
routing of various packets through diverse autonomous system to
interconnect them. This is uniquely important since it identifies each
system when routing and managing routing table for external network
for autonomous system are around their borders.
b) This is the routing between independent operating networks AS. They
operate on their self-interests and provide a global connection. AS
advertise reachability to the destination. They operate on a path vector
protocol that is the BGP. They have three essential attributes of
communication.
1. Destination Prefix such as the ip prefix
2. Next hop ip address destination
3. AS path that contains a sequence of AS numbers.
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c) This type of routing protocol operates inside the AS in that each AS
chooses one or more intradomain routing protocols. The operation is
based on unreachable datagram delivery. There two major attributes
that are discussed
1. Distance Vector Protocol – in this the exchange of information
is periodically
2. Link state Protocol – in this a shorter and most alternative path
is opened first and also it’s able to share information
periodically to each other.
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d) Similarities
Both Border Gateway Protocol and Distance vector protocol are able to
exchange information from one point to point
Differences
Border Gateway Protocol - identifies each system when routing and
managing routing table for external network for autonomous system
Distance Vector Protocol – it’s regarded as slow because it exchanges
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information one at a period of time periodically.
e) There are two major varieties of routing protocols, they include:
 Inter domain routing- it is restricted which simply means that
majority of the operations are handled inside the autonomous
system
 Intra domain routing- in this is network operations are operated
under a single common administration.
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Total marks awarded 25 (max)
Less late penalties
Less plagiarism penalties
Total marks earned
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References
Cohe, D., Postel, J. B., & Rom, R. (2010, May). IP addressing and routing in a local wireless network.
In [Proceedings] IEEE INFOCOM'92: The Conference on Computer Communications(pp.
626-632). IEEE.
Lee, S. J., Gerla, M., & Chiang, C. C. (2010). On-demand multicast routing protocol. In WCNC. 1999
IEEE Wireless Communications and Networking Conference (Cat. No. 99TH8466) (Vol. 3, pp.
1298-1302). IEEE.
Jinhua, G., & Kejian, X. (2013, January). ARP spoofing detection algorithm using ICMP protocol.
In 2013 International Conference on Computer Communication and Informatics (pp. 1-6).
IEEE.
Sohn, T., Moon, J., Lee, S., Lee, D. H., & Lim, J. (2013, November). Covert channel detection in the
ICMP payload using support vector machine. In International Symposium on Computer and
Information Sciences (pp. 828-835). Springer, Berlin, Heidelberg.