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Network Layer / IP

24 questions · 12 topics

2013 Q3(a)Network Layer / IPLink State· 1 marks

Given an example of a link state routing protocol you have come across in your course.

OSPFrouting
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2013 Q3(b)Network Layer / IPDistance Vector· 8 marks

Figure 1 is a diagrammatical depiction of a network of routers with link costs. Copy the table given in the figure and complete the distance table using the Distance Vector routing algorithm executed at node B. Assume that routing loops are prevented. Finally indicate in a table the resulting routing table.

Bellman-Fordrouting table
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2013 Q3(c)Network Layer / IPIPv4· 2 marks

What is the binary equivalent of the IP address 223.1.3.27?

addressingbinary
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2013 Q3(d)Network Layer / IPTunneling· 2 marks

It is said that when IPv6 tunnels through IPv4 routers, IPv6 treats the IPv4 tunnels as link-layer protocols. Do you agree with this statement? Why or why not?

IPv6 transitionencapsulation
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2013 Q3(e)Network Layer / IPSubnetting· 3 marks

Consider a router that interconnects three subnets: Subnet 1, Subnet 2, and Subnet 3. Suppose all of the interfaces in each of the three subnets are required to have the prefix 223.1.17/24. Also suppose that Subnet 1 is required to support upto 125 interfaces, and Subnect 2 and 3 are each required to support up to 60 interfaces. Provide three network addresses (of the form a.b.c.d/x) that satisfy these constraints.

IP addressingCIDR
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2013 Q3(f)Network Layer / IPIPv6· 4 marks

IPv6 removed fragmentation in routers. Explain how IPv6 deals with different maximum transmission units (MTUs) of different links along a path. What is the advantage of this approach when compared to IPv4 fragmentation?

MTUfragmentation
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2013 Q3(g)Network Layer / IPFragmentation· 5 marks

Consider sending a 3,000 byte datagram into a link that has an MTU of 700 bytes. Suppose the orginal datagram is stamped with identification number 422. How many fragments are generated? Give the values of the various related header fields of each fragment sent using IPv4.

MTUIPv4 header
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2014 Q3(a)Network Layer / IPNetwork Troubleshooting· 3 marks

You are unable to reach hosts on the Internet. Briefly explain how you would test if the problem is within your network or outside your network (ie your service provider or further upstream).

ICMPtroubleshooting
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2014 Q3(b)Network Layer / IPIP Addressing· 3 marks

Clearly explain the difference between unicast, multicast and broadcast traffic at Layer 3.

IProuting
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2014 Q3(c)Network Layer / IPIPv6· 3 marks

Briefly describe three limitations of IPv4 that justify the development and deployment of IPv6.

IPv4IPv6addressing
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2014 Q3(d)(i)Network Layer / IPCIDR· 3 marks

For each of the groups of IP addresses below, identify how many distinct networks are represented, provide the network number(s) in each case and give a brief reason for your answer. 10.5.5.1 10.5.6.2 10.7.8.3

CIDRclassfulnetwork number
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2014 Q3(d)(ii)Network Layer / IPCIDR· 3 marks

For each of the groups of IP addresses below, identify how many distinct networks are represented, provide the network number(s) in each case and give a brief reason for your answer. 10.5.5.1/16 10.5.6.2/16 10.7.8.3/16

CIDRnetwork number
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2014 Q3(d)(iii)Network Layer / IPCIDR· 3 marks

For each of the groups of IP addresses below, identify how many distinct networks are represented, provide the network number(s) in each case and give a brief reason for your answer. 10.5.5.1/24 10.5.6.2/24 10.7.8.3/24

CIDRnetwork number
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2014 Q3(e)Network Layer / IPIPv4· 4 marks

Suppose datagrams are limited to 1500 bytes (including header) between source Host A and destination Host B. Assuming a 20 byte IP header, how many datagrams would be required to send an MP3 consisting of 5 million bytes.

MTUIPv4 header
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2014 Q3(f)Network Layer / IPDijkstra· 5 marks

Dijkstra’s algorithm can be implemented in two different ways, one of which has a complexity of O(n2) and one of which has a complexity of O(n log n). Choose one of the implementations and briefly justify its complexity.

routingcomplexity
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2015 Q3(a)Network Layer / IPDijkstra· 6 marks

Given the network shown above, show the development of the routing table for node A using Dijkstra’s algorithm. You must show your work and the final routing table (next hop and path cost for each destination) for full marks.

link stateshortest path
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2015 Q3(b)(i)Network Layer / IPDistance Vector· 3 marks

Node A is using distance vector routing. The current distance table and routing table at Node A are shown below. Current distance table at Node A (rows: to; columns: via B C D E) to B: via B = 2 to C: via C = 1 to D: – to E: via E = 8 Current routing table at Node A dest | next hop | cost B | B | 2 C | C | 1 E | E | 8 Node A receives the following vector from neighbour Node B [A, 2 C, 2 D, 2 E, 5] Show the updated distance table at A after it processes this vector.

Bellman-Forddistance table
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2015 Q3(b)(ii)Network Layer / IPDistance Vector· 2 marks

Node A is using distance vector routing. The current distance table and routing table at Node A are shown below. Current distance table at Node A (rows: to; columns: via B C D E) to B: via B = 2 to C: via C = 1 to D: – to E: via E = 8 Current routing table at Node A dest | next hop | cost B | B | 2 C | C | 1 E | E | 8 What vector, if any, will be sent by A after its distance table has been updated?

Bellman-Fordadvertisement
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2015 Q4(a)Network Layer / IPForwarding· 2 marks

Suppose there are three routers between a source host and a destination host. Ignoring fragmentation, an IP datagram sent from the source host to the destination host will travel over how many interfaces? How many forwarding tables will be indexed to move the datagram from the source to the destination?

IPforwarding
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2015 Q4(b)Network Layer / IPCIDR· 2 marks

What is the binary equivalent of the network address of the IP address 223.1.3.27/16?

addressingbinary
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2015 Q4(c)Network Layer / IPSubnetting· 7 marks

You have a network 115.64.4.0/22 that you want to create subnets on. The subnets need to support up to 60 hosts each. How many bits would you allocate for the host part of the subnets? How many such subnets can you support?

IP addressingCIDR
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2015 Q4(d)Network Layer / IPIPv6· 3 marks

Briefly describe three limitations (1 mark per limitation) of IPv4 that justify the development and deployment of IPv6.

IPv4IPv6addressing
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2015 Q4(e)Network Layer / IPForwarding· 2 marks

Suppose Host A sends Host B a TCP segment encapsulated in an IP datagram. When Host B receives the datagram, how does the network layer in Host B know it should pass the segment (that is, the payload of the datagram) to TCP rather than to UDP or to something else?

IPdemultiplexing
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2015 Q4(f)Network Layer / IPIPv6· 2 marks

IPv6 uses 128 bit addresses compare to IPv4, so it will take longer for routers to process IPv6 datagrams. Explain clearly by providing one argument why you agree or disagree with this statement?

IPv6headerforwarding
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