Course: Semester: CEG3185 Winter 2015 Professor: Room: Phone: Email: Jiying Zhao STE 5019 (613)562-5800 x 6667 [email protected] Assignment 4 Weight: 5% Posted: March 25, 2015 Due: April 10, 2015, noon 1. [15 marks] Define the following parameters for a switching network: N = number of hops between two given end systems L = message length in bits B = data rate, in bits per second (bps), on all links P = fixed packet size, in bits H = overhead (header), bits per packet S = call setup time (circuits switching or virtual circuit) in seconds R = call release time (circuits switching or virtual circuit) in seconds D = propagation delay per hop in seconds (a) For N=4, L=3200, B=9600, P=1024, H=16, S=0.2, D=0.001, compute the end-to-end delay for circuit switching, virtual circuit packet switching, and datagram packet switching. Assume that there are no acknowledgments. Ignore processing delay at nodes. (b) Derive general expressions for the three techniques of part (a), taken two at a time (three expressions in all), showing the conditions under which the delays are equal. 2. [5 marks] Although not explicitly stated, the Internet Protocol (IP) specification, RFC 791, defines the minimum packet size at network technology must support to allow IP to run over it. (a) Read Section 3.2 of RFC 791 to find out that value. What is it? (b) Discuss the reason for adopting that specific value. 3. [10 marks] A 4480-byte IP datagram (with Identification of 07777H) is to be transmitted and needs to be fragmented because it will pass through an Ethernet with a maximum payload of 1500 bytes. Show the Identification, Total Length, More Flag, and Fragment Offset values in each of the resulting fragments. 4. [10 marks] Refer to Frame 3. By fragmenting the carried IP datagram to two fragments with about equal length, form two corresponding Ethernet-II frames. Frame 3: 0000 0010 0020 0030 78 00 3b ff 8d 30 61 ff f7 2f 04 54 b0 f2 2a f3 6d 40 13 00 72 00 88 00 00 80 33 02 1d 06 55 04 D:\data\zhao\2015w\ceg3185\assignment4_ceg3185_2015w.doc 09 91 aa 04 41 3a 51 ec cc c0 00 01 59 a8 00 01 08 00 00 04 00 45 00 11 3d 81 00 70 02 02 x...mr...A.Y..E. .0/.@....:....=. ;a.*..3U.Q....p. ..T........... Page 1 of 4 5. [15 marks] In the following figure, all the LANs, routers, bridge, and computers belong to one company. The company has Class C addresses, 192.121.152.0. Help the company partition the network into the needed number of sub-networks (allow as many computers as possible in each subnetwork), by identifying the subnet mask, assigning addresses to each of the sub-networks, assigning needed IP addresses to routers and computers. Station 1 LAN A LAN B Router 1 LAN C Bridge 1 LAN D Router 2 Station 2 D:\data\zhao\2015w\ceg3185\assignment4_ceg3185_2015w.doc Page 2 of 4 6. [15 marks] Compute RIP routing table for all the routers in the following figure. Then describe how an IP datagram is routed from a computer on N5 to a computer on N2. In the figure, rectangles are used to represent routers and clouds are used to represent networks. N2 A D N1 N3 C N5 F B E N4 7. [15 marks] Apply Dijkstra’s algorithm to the following network to generate a shortest-path-tree for node C and node D, and build a routing table for node C and node D. D:\data\zhao\2015w\ceg3185\assignment4_ceg3185_2015w.doc Page 3 of 4 8. [15 marks] You are given the following internetworking scenario: Router 1 A 143.24.56.1 a c b 155.23.76.12 Token Ring 155.23.77.254 143.24.56.254 Ethernet Bridge Ethernet B 132.14.73.1 155.23.77.253 Ethernet Router 2 c 155.23.76.25 b a Token Ring 132.14.73.156 The above IP network has just come on-line (i.e. all devices have just powered up). The routers contain the following decision tables: Network Subnetwork 132.14.0.0 143.24.56.0 155.23.76.0 155.23.77.0 Network Subnetwork 143.24.0.0 155.23.76.0 155.23.77.0 132.14.73.0 Router 1 Router Address Network Mask Interface 155.23.76.25 local local local 255.255.0.0 255.255.255.0 255.255.255.0 255.255.255.0 c a c b Router 2 Router Address Network Mask Interface 255.255.0.0 255.255.255.0 255.255.255.0 255.255.255.0 c b c a 155.23.77.254 local local local (a) List the actions and routing decisions taken by all stations and routers to route an IP datagram containing an ICMP Echo Request transmitted by Station A to Station B. (b) List the actions and routing decisions taken by all stations and routers to route an IP datagram containing an ICMP Echo Reply returned by Station B to Station A. D:\data\zhao\2015w\ceg3185\assignment4_ceg3185_2015w.doc Page 4 of 4