Network Routing and Switching Written Assessment
Objectives -
This assessment task requires you to demonstrate your knowledge of basic routing concepts by completing a number of exercise questions.
Question 1 - Routing table construction
Given the following network, construct the routing table for routers R2 and R3.
Question 2 - Allocating subnets from a block
You are the Network Administrator for a startup company that has been granted a new block of addresses starting with the address 139.145.56.0/22.
a) Calculate the total number of addresses available in this block including all the special addresses. Show your calculation.
b) As Network Administrator, you need to distribute the available addresses on a departmental needs basis (meaning not allocating more than you have to), with 4 new subnets determined as follows:
Marketing needs 65 addresses
Accounting needs100 addresses
Head Office needs 33 addresses and,
Customer Services needs 13 addresses.
Create the 4 subnets. For each subnet, list the subnet or first address, the last address, and the subnet mask in CIDR format. Show your calculations for all subnets, briefly showing how you arrived at the sub-block addresses.
c) How many addresses are left unallocated? Show your calculation.
Question 3 - Fragmentation
An IP datagram 5,600 bytes long (including header with no options) arrives at a router, which determines that the next destination has an MTU of 1,500 bytes. Answer the following questions, showing your calculations and reasoning.
a) Assuming that the router decides to fragment the packet into 4 fragments, for each fragment, determine a correct size, and identify the starting byte and ending byte.
b) Calculate the fragmentation offset for each fragment.
c) The total number of bytes from all 4 fragments leaving the router should be greater than the initial datagram size that arrived. Explain why this is so.
Hints: Working out part (a) can be a fiddly (messy) exercise and you may find it helpful to use a spreadsheet to work out appropriate sizes and offsets. Remember that the offset needs to be evenly divisible by 8, as explained in the textbook. You may need to do additional reading to understand the process if it is unclear to you - Forouzan is a good place to start.
Question 4: Advanced routing study
Research and review appropriate materials, including the textbook, and answer the first two questions (a & b).
a) Define the terms and discuss the relationship between Autonomous Systems, Inter-domain routing, and Intra-domain routing.
b) Identify the major routing protocols associated with Inter-domain and Intra-domain routing and list their similarities and differences. Finish by commenting on why we need different protocols for Inter-domain and Intra-domain routing.
Study the two articles listed below - both are freely available on the Internet. You may use other references in addition to these, as needed. Then answer the remaining 3 questions (c, d & e).
c) Briefly summarize in your own words the problems with current routing methods that the authors have identified.
d) Contrast and compare the concepts of embedded routing and extensible routing.
e) How does the proposal of Routing As A Service (RAAS or just RAS) address the problems with current routing methods?
The two articles for questions 3 - 5 (both articles have the same title):
1. Routing as a Service by K.Lakshminarayanan et al
2. Routing as a Service by K.Lakshminarayanan, Stoica, and Shenker
Question 5 - IPv6 Packets
An IPv6 packet travelling within an Autonomous System, consists of a base header, extension headers, a TCP segment and data. The data is 128,000 bytes long (jumbo payload). The following diagram shows the packet:
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Version
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Traffic class
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Flow label
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Payload length
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Next header
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Hop limit
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Source Address
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Destination Address
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Hop-by-hop ext hdr
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Source port address
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Destination port address
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Sequence number
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Acknowledgement number
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HLEN
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Reserved
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Control
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Window size
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Checksum
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Urgent pointer
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128000 bytes of data
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Determine a correct or valid value for the following fields in the base header with a brief explanation of the value you selected. Note: the brief explanation is half the marks.
- Version;
- Payload Length;
- Next Header;
- Hop limit:
- Source Address and Destination Address.
Do not type your answers here: type it in the Answers Template provided.
Suggested sources of information: Forouzan (textbook) chapter 27.
Attachment:- Assignment File.rar