1. Abstract:
A routing protocol specifies the method of communication among routers
used in the inter connection of networks. There are many protocols like
OSPF, RIP, EIGRP, OPNET, IGRP, etc. The Routing Information Protocol (RIP)
comes under the distance vector algorithm and the Open Shortest Path First
Protocol (OSPF) is a link state routing algorithm. In RIP (Routing Information
Protocol) If any link failure with any new path happened, then the network
will update routing table again and find another shortest path. Whenever all
link failures are finished the first used path will be used again after updating,
that means the signal will back to the first path below. That if both failures
finished at the same time, but if not then, the signal will back to the path
which was used before that link failure happen.
On the other hand, Link State Routing Protocol (OSPF) works on a more
complicated algorithm where links costs have been defined according to the
bandwidth of that link, and the routing table for the entire network will be
set regarding to each node with it is neighbours. One router will be the
designated router that will be responsible for sending the link advertisement
to the other routers. To illustrate that, the same topology will be deployed
again and the configuration for the routing protocol will be set to work.
2. RIP (Routing Information Protocol)
RIP is intra domain routing protocols which is usually known as Distance
Routing Protocol. Here is referring to the number of hops which is calculated
by the router to reach a specific destination. I,e , the path that the router
chooses to reach the subnet. It is mainly used in small network. distance
vector routing protocol (RIP) defines the best path as the path with the least
number of router the lowest hop counts’ path) whatever the bandwidth of
that path was, and then it will always choose that path unless a link failure
happened.
Important Facts Of RIP:
1. Periodic :
In RIP the routing updates are sent in regular interval. The default interval
timer is 30 seconds.
2. Full Update:
The router sends full updates each and every time, Instead of sending changed
or new routing information.
RIP Configuration:
3. Concept of Route by Distance Vector Protocol:
Router 0:
Source Destination Next Hop Cost in hops
Con 192.168.1.0 N/A 0
Con 192.168.2.0 N/A 0
RIP 192.168.3.0 192.168.2.2 1
RIP 192.168.4.0 192.168.2.2 1
RIP 192.168.5.0 192.168.2.2 2
4. Router 1:
Source Destination Next Hop Cost in hops
Con 192.168.2.0 N/A 0
Con 192.168.4.0 N/A 0
Con 192.168.3.0 N/A 1
RIP 192.168.1.0 192.168.2.1 1
RIP 192.168.5.0 192.168.2.1 1
Router 2:
Source Destination Next Hop Cost in hops
Con 192.168.4.0 N/A 0
Con 192.168.5.0 N/A 0
RIP 192.168.1.0 192.168.4.1 2
RIP 192.168.2.0 192.168.4.1 1
RIP 192.168.3.0 192.168.4.1 1
Disadvantages of RIP:
1. It converges slowly, especially on large networks
2. It doesn’t have knowledge of the bandwidth of a link
3. It doesn’t support multiple paths for the same route
4. Routing updates can require significant bandwidth, as the entire routing
table is sent when a link’s status changes
5. Prone to routing loops
6. It can have only 16 hops.
Advantages of RIP:
1. Very easy to understand and configure
2. It is almost guaranteed to be supported by all routers
3. Generally loop free
5. OSPF (Open Shortest Path First)
It uses link-state technology in which routers send each other
information about the direct connections and links to all routers in the
network. Each OSPF router required to maintains an identical database to
describe the autonomous system's topology. From this database, a routing
table is calculated by constructing a shortest path tree. OSPF calculates the
cost of the path according to that link bandwidth even if that path was not
with the lowest routers number. OSPF is implemented as a program in the
network layer, using the service of the IP for propagation. The protocol
recalculates routes when network topology changes, using the
Dijkstra algorithm, and minimises the routing protocol traffic that it
generates. It provides support for multiple paths of equal cost.
Configuration of OSPF:
6. Disadvantages of OSPF:
1. OSPF is very processor intensive.
2. OSPF maintains multiple copies of routing information, increasing the
amount of memory needed.
3. Using areas, OSPF can be logically segmented (this can be a good thing and a
bad thing).
4. OSPF is not as easy to learn as some other protocols.
5. In the case where an entire network is running OSPF, and one link within it is
"bouncing" every few seconds, OSPF updates would dominate the network by
informing every other router every time the link changed state. OSPF routers
check the status of other routers on the network by sending a small hello
packet at regular intervals.
Advantages of OSPF:
1. OSPF is a Link State Algorithm
2. OSPF supports Variable Length Subnet Mask (VLSM)
3.OSPF uses multicasting within areas.
4. After initialization, OSPF only sends updates on routing table sections
which have changed, it does not send the entire routing table.
