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A comprehensive overview of routing protocols in networking, focusing on rip, eigrp, and ospf. It explains the fundamental concepts of routing, routing tables, and the different types of routing protocols. The document delves into the characteristics, configuration, and verification of each protocol, providing valuable insights for network administrators and students.
Typology: Summaries
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Routing is the method by which network devices direct messages
across networks to arrive at the correct destination.
The router is responsible for the routing of traffic between
networks.
When a router has two or more paths to a destination with equal
cost metrics, then the router forwards the packets using both paths
equally.
If multiple paths to a destination are configured on a router, the
path installed in the routing table is the one with the best (lowest)
Administrative Distance (AD).
Administrative Distance is the “trustworthiness” of the route
The Lower the AD the more trustworthy the route.
A router can learn about remote networks in one of two ways:
table using static routes.
dynamic routing protocol.
Why Use Static Routing?
Static routing provides some advantages over dynamic routing,
including:
Better security, because of not advertised over the network.
Use less bandwidth than dynamic routing protocols, no CPU cycles
are used to calculate and communicate routes.
The path is known to send data.
following format:
ip route [destination_network] [subnet_mask] [next hop IP/exit
interface]
To remove static route
No ip route [destination_network] [subnet_mask] [next hop
IP/exit interface]
A dynamic routing protocol learns all available routes, places the
best routes into the routing table, and removes routes when they are
no longer valid.
The method that a routing protocol uses to determine the best route
to a destination network is called a routing algorithm.
There are two main classes of routing algorithms:
o Distance vector
o Link state
Each type uses a different method for determining the best route to a
destination network.
When all the routers in a network have updated their tables to reflect
the new route, the routers are said to have converged.
Protocol under Distance vector protocol are, RIPv1&v2, IGRP
and EIGRP.
Distance vector routing protocols
Share updates between neighbors
Not aware of the network topology
Some send periodic updates to broadcast IP 255.255.255.
even if topology has not changed
Updates consume bandwidth and network device CPU resources
RIPv2 and EIGRP use multicast addresses
EIGRP will only send an update when topology has changed
Enterprise networks and ISPs use link-state protocols because of
their hierarchical design and ability to scale for large networks.
Distance vector routing protocols are usually not the right choice
for a complex enterprise network.
Link-state routing protocols, such as OSPF, do not send frequent
periodic updates of the entire routing table.
Instead, after the network converges, a link-state protocol sends an
update only when a change in the topology occurs, such as a link
going down.
RIPv2 is a classless routing protocol.
RIPv2 also has the ability to turn off automatic summarization of
routes.
RIP v1 broadcasts these updates to 255.255.255.255 and RIP V
multicast its update to 224.0.0.9.
Multicasts take up less network bandwidth than broadcasts.
Devices that are not configured for RIPv2 discard multicasts at
the Data Link Layer.
Before configuring RIP, assign IP addresses and masks to all
interfaces that participate in routing.
Set the clock rate where necessary on serial links.
The basic RIP configuration consists of:-
RIPv
o Router(config)#router rip
o Router(config-router)#network [network address]
RIPv
o Router(config)#router rip
o Router(config)#version 2
o Router(config-router)#network [network address]
The limitations of RIP led to the development of more advanced
protocols.
All of these features makes EIGRP an excellent choice for large,
multi-protocol networks that employ primarily Cisco devices.
The two main goals of EIGRP are:-
Provide a loop-free routing environment and
Rapid convergence.
The Diffusing Update Algorithm (DUAL) used by EIGRP
guarantees loop-free operation while it calculates routes.
Its maximum hop count of 255 supports large networks.
To store network information from the updates and support
rapid convergence, EIGRP maintains multiple tables.
EIGRP routers keep route and topology information readily
available in RAM so that they can react quickly to changes.
EIGRP maintains three interconnected tables:
o Neighbor table
o Topology table
o Routing table
Routing Table
Whereas the topology table contains information about many
possible paths to a network destination, the routing table
displays only the best paths.
EIGRP displays information about routes in two ways:
The routing table labels routes learned through EIGRP with a
EIGRP tags dynamic or static routes learned from other
routing protocols as D EX.
To begin the EIGRP routing process, use two steps:
Step 1
