Sunday, January 5, 2014

Network Engineering1ST semester December 2013

MTECH Information Technology 1ST semester December 2013
Network Engineering
Part A(10 x 2 = 20)
1. Packet switching is more suitable than circuit switching for data communication network. Justify this statement.
2. Whether Ethernet is based on deterministic model or probabilistic model? Justify your answer.
3. State any 4 QoS metrics?
4. Available bandwidth of a channel is 10Mbps.10 users share this channel. All of them claim 2 Mbps consistently. Is it possible for the channel to accommodate all 10 users? Find the maximum number of user that can be accommodated at the current rate.
5. Write short notes on controlled load services in integrated services network.
6. What do you mean by ‘in profile’ and ‘out of profile’ in differentiated service network?
7. Why is it necessary to retain static routes even though dynamic routing protocol is in use?
8. Mention the purpose for which a bridge is used in local area networks.
9. Give examples for the protocols that maintain routing tables and the protocols that forward datagrams in a router.
10. State the major features of Software Defined Network.

PART B (5 x 16 =80)
11. (I) Consider network topology in Figure 1.
clip_image001
Explain how the packet will be routed from 1 to 6 if the networks assume datagram network organization and virtual circuit network organization. (10)
(II) Explain network externalities with an example. (6)

12. (A) (I). An ATM network has been designed and implemented so that the Peak Cell Rate is 64Kbps and the Sustained Cell Rate is 25 Kbps. For this network calculate Maximum Burst Size, Maximum Burst Duration and Burst Tolerance.
Hint:
MBS = PCR/53 bytes (unit is number of cells), TMBS = MBS/PCR (unit is milliseconds or seconds) and BT = (MBS-1)((1/SCR)-(1/PCR)) (8)
(II). Differentiate best effort model and Guaranteed Service model. (8)
(OR)
(B). (I).Suppose a router has accepted flows with TSpecs shown in Table 1,described in terms of token bucket filters with token rate r packets per second and bucket depth of B packets. All flows are in the same direction and the router can forward one packet every 0.1 second.
Table 1
r B
1 10
2 4
4 1

a) What is the maximum delay a packet might face?
b) What is the minimum number of packets from the third flow that the router would send over 2.0 seconds, assuming the flow sent packets ar its maximum rate uniformly? (8)
(II). Explain the Laissez Faire approach of providing QoS and compare its merits and demerits with reservation based approaches. (8)

13. (A). (I). Explain the ‘soft state’ and ‘receiver oriented approach’ followed by RSVP. (8)
(II). Draw the domain diagram of Differentiated Services network and explain the various components of the traffic conditioner at the ingress router.(8)
(OR)
(B). (I). Explain the assignment of labels and the maintenance of MPLS switching table with a sample topology. (8)
(II). Whether RTP is a transport layer protocol or application layer protocol or both? Analyze from different perspectives. (8)

14. (A). (I) Consider the network topology shown in figure 2.
clip_image002
Assume that the distance vector algorithm is followed to maintain the routing table and the metric used is delay. Delay for JA, JI, JH and JK are 8msec, 10msec, 12msec and 6msec respectively. J receives the distance vector from A, I, H and K (4 columns in the matrix as follows).
A I H K
A 0 24 20 21
B 12 36 31 28
C 25 18 19 36
D 40 27 8 24
E 14 7 30 22
F 23 20 19 40
G 18 31 6 31
H 17 20 0 19
I 21 0 14 22
J 9 11 7 10
K 24 22 22 0
L 29 33 9 9

Compute the new routing table of J to destinations A,B,C,D,E,F,G,H,I,J,K and L with corresponding delays and outgoing lines. (8)
(II) Draw the header diagram of RIPv2 and explain its various fields. (8)
(OR)
(B). (I). Consider the network topology shown in figure 3 using link routing.
clip_image003
Assume that link B-F fails. After the failure the following events take place in sequence.
a) Node H is added to the right with a connection to G
b) Node D is added to the left side with a connection to C
c) A new link DA is added.
The failed link B-F is restored .Describe what link state packets will flood back and forth. Assume that initial sequence number at all nodes is I, and that no packet time out. And that both the ends of a link use the same sequence number in their LSP for that link, Greater than any sequence number any used before. (8)
(II) Explain the following of OSPF
a) Areas and Backbone area (3)
b) Designated router and backup designated router (3)
c) Routing table and adjacency database (2)

15. (A) (I). Describe any one of the modern protocol stack for software defined networks. (8)
(II). Explain the terms neighbor, NLRI/Prefix, router ID, router path of BGP. Also explain the following message types of BGP: Open, Update, Keepalive and Notification. (8)
(OR)
(B) (I). Explain the data plane support for software defined networking. (8)
(II). Explain the architecture of a typical router with a neat diagram. (8)