Routing Algorithms
1.
Compare between connectionless service and connection-oriented service by network name of each service, circuit setup requiring, Addressing, routing, effect of router failure. network name connectionless service datagram network circuit setup requiring Not needed
Addressing Each packet contains full source and destination address connection-oriented service a virtual-circuit network required
Each packet contains a short VC number routing Each packet is routed independently Router chosen when VC is set up , all packets follow it effect of router failure None, except for packets lost during the crash
All VCs that passed through the failed router are terminated
2.
the network that uses connectionless service is called a datagram network . the network that uses connection-oriented service is called a virtual-circuit .
3.
three metrics to measure the path length between routers are number of hops , geographic distance or propagation delay .
4.
.
propagation delay is a metric of measuring path length by sending over the line special ECHO packets that the other side just timestamps it and sends back as fast as it can.
5.
the 2 parts in each entry in the routing table are destination and outgoing line (next node).
6.
the packet type that is used to measure the propagation delay with neighbors routers is timestamp packet .
7.
the packet type that is used to learn who the router neighbors are Hello packet .
8.
why does hierarchical routing reduce the routing table size?
Because a router does not need know each station IP address, it just need to know the network address of each region.
9.
Two examples on of broadcasting routing are flooding and reverse path forwarding .
10.
Flooding is a simple local technique, in which every incoming packet is sent out on every outgoing line except the one it arrived on.
11.
Distance Vector Routing is a routing algorithm Update routing table by exchanging information
(routing tables) with the neighbors.
12.
. Link State Routing is a routing algorithm in which each router constructs a packet telling all it has just learned about its neighbors and the cost metric to each of them.
13.
. Hierarchical Routing is a routing algorithm reduces the routing tables size.
14.
Broadcast Routing is sending a packet to all destinations simultaneously.
15.
The measures that are taken to stop generating vast numbers of duplicate packets in flooding routing algorithm are to have a hop counter or to have a sequence number .

16.
Match between each routing algorithm and its function routing algorithm
1.
Distance Vector Routing
2.
Link State Routing
3.
Hierarchical Routing
4.
Broadcast Routing
5.
flooding function
( 1 )Update routing table by exchanging information (routing tables) with the neighbors.
( 2 )in which each router constructs a packet telling all it has just learned about its neighbors and the cost metric to each of them.
( 3 )reduces the routing tables size
( 4 )Is sending a packet to all destinations simultaneously.
( 5 )a simple local technique, in which every incoming packet is sent out on every outgoing line except the one it arrived on.
6.
Consider the following network. What is J’s new routing table? Give both the outgoing line to use and the propagation delay using Distance Vector Routing
7.
Consider the following network. Distance vector routing is used, and the following vectors have just come in to router C: from B: (5, 0, 8, 12, 6, 2); from D: (16, 12, 6, 0, 9, 10); and from E: (7, 6, 3, 9, 0, 4).
The cost of the links from C to B, D, and E, are 6, 3, and 5, respectively. What is C’s new routing table?
Give both the outgoing line to use and the cost.
Answer:
TO B
A 5
B
C
0
8
D
E
F
12
6
2
A-B delay 2
D
A 16
B 12
C 6
D 0
E 9
F 10
A-C delay 1
E
A 7
B 6
C 3
D 9
E 0
F 4
A-E delay 5
Delay from A
A 7
B 2
C ---
D 1
E 5
F 4
Outgoing
Line
B
B
---
D
E
B
A Routing Table

8.
Find the shortest path from the router A to the router D, and determine the propagation delay and the outgoing line at each router.
Answer:
A --> G --> E --> F --> C --> D