Question

12 2 5 Figure 1: A set of intersecting rings 3. [20 points] Again refer to the above figure. Label each approximately at its center from| the set {α, β, δ, γ,e). Each ring represents an autonomous system (AS 3.1. What is meant by the term autonomous sytem? 3.2. For the entire network from S to D, are there any single points of failure? If so, identify each both by the AS and the node number. 3.3. Which nodes correspond to interion nodes for each AS? 3.4. Assume that the maximum throughput of each segment is related to the metric (weight) associated with each segment as follows: 1 Tbit sec1, 2 100 Gbit sec1, 3-10 Gbit sec1,4-1 Gbit sec1 at is the maximum throughput fromm to D; show your work and reasoning, not just a numerical answer

Answer 1

3.1

Autonomous system refers to regulatory mechanism of governing and managing heterogeneous networks which are huge in size by organisations who own the networks (like ISPs,Telecom Providers,Governments,Universities etc.,) where all the networks have a common routing logic and routing policies.Each of the subnetwork present in the Autonomous system is assigned with a globally unique value of 16 digits length called as AutonomousSystem Number.(ASN).The data is routed in the form of packets between these subnets with the help of IGP(Interior Gateway Protocol).Data beyond an AS wil be routed with the help of BGP(Border Gateway Protocol)

In simple words,an AS could be considered as a routing domain in which all the networks within an it communicate the routing information(exchange routing tables etc.,) to each other

3.2

Single Point of Failure

A Single Point of Failure is a node in which whose failure will cause the entire network to break down

The given network has no Single Point if failures as there are alternative routes through the other nodes at every AS so that the data can be transferred to other nodes in the neighbouring AS through an alternative route if a node in the optimal path is failed.

AS NO.	NO. OF ALTERNATE PATHS
$\alpha$	2
$\beta$	3
$\delta$	5
$\gamma$	2
$\varepsilon$	2

Interior nodes :

The interior node of an Autonomous system is a node which belongs to a single autonomous system only.

For the given network,The interior nodes for each AS are given below:

AS	Interior nodes
$\alpha$	1
$\beta$	0
$\delta$	0
$\gamma$	0
$\varepsilon$	1

Note : The nodes lying on the intersections of AS will represent border routers(non-internal).

Calculating the Throughput:

Assuming the bandwidth metric between each segment as :

Metric(K1)	Bandwidth
1	1 Tb/s
2	100 Gb/s
3	10 Gb/s
4	1 Gb/s
5	0.5 Gb/s
8	0.25 Gb/s
12	0.125 Gb/s

1 Tbf s .125 6bfs 1eGbf s tbf s Gbfs 1 6bfs 4 1 Gbf 1 Gbfs Gbfs 2 108 Gbf s 10Gb/ s 8 9.5 Gbfs 0.25 6b/s 1 Tbf s

For a network the overall throughput is approximately equal to the lowest bandwidth in its segments

The given network has a highest bandwidth of 1 Tb/s and a lowest bandwidth of 0.125Gb/s(125Mbps)

The possible routes in the network are shown in the figure below:

2- 1 Tb/s .125 6b 12 18Gb 1 tbfs 1 Gbfs 1 6bfs 4 1 Gbf 4 E Gbfs 1 Gbis 4 3 2 1 Gbfs19Gb/ s 100 Gbfs 10Gb/ s 8 95 Gbf 8.25 6bf

In the above diagram,three possible routes are shown. For each route, the bandwidths are shown as follows:

Route	Throughput
Route-1	0.125 Gbps
Route-2	10 Gbps
Route-3	10 Gbps

Route 2 and 3 have optimal bandwidths, of 10Gbps each

The effective throughput will be

Maximum: 10 Gb/s

Minimum :0.125 Gb/s (125Mb/s)