SmartPCTricks.com already started Cisco Networking tutorials. In previous article we had covered basic Cisco router configuration in detail, it was a CCNA routing protocols study guide. Today I planned to give you CCNA guide to Cisco networking, that is complete idea about different types of routing protocols. As we know Router is a layer 3 (Network Layer- OSI Model) device used to inter connect two or more different networks, so a routing protocol is a protocol that defines how routers communicate with each other for broadcasting information. This article covers Static Routing and Dynamic Routing.
Cisco routers work with IOS (Internet Operating System), Routing protocols are the instructions embedded in IOS that allow routers to transfer information between networks. Thus IOS together with routing protocol lets routers to decide available routes as well as choose the most effective paths for network traffic.
Before starting CCNA online training, I will figure out why we need router and routing. As we all know Router interconnects 2 or more networks, if so why we need routing?
When we need a Routing
There is no need of any routing if there are 2 or more networks connected in same router because the router knows the networks which are attached directly. Refer the following.
In case of 2 or more networks interconnected with 2 or more router we should use routing. Because a router doesn’t know anything about networks those attached to the neighboring router.
Here Router 1 knows about Network 1 and Network 2 because directly connected networks. But Router 1 don’t know about Network 3 because it is attached to neighboring Router 2. In such situation we should tell to Router 1 about Network 3 (Router 2 about Network 1 & 2). This process is called Routing
There are mainly two types of Routing namely Static Routing and Dynamic Routing.
A static route is a manually designed route on your router. Static routes are usually employed in minor networks. For networks that have thousands of routes, static routes are not applicable, since you would have to configure each route independently.
A static routing in the sense when we manually add all possible routes in each router’s routing table.
There are advantages and disadvantages to static routing
Advantages Static routing
- No overload on the router CPU.
- There is no bandwidth usage between routers.
- More secure since administrator can permit routing access to certain networks only.
Disadvantages Static routing
- The administrator should aware about each internetwork and how each router interconnected.
- While adding new network, administrator has to add manually the new route in all routers.
- Impossible in huge networks since maintaining it would be a full-time job in itself.
In my next article we will cover Static routing in detail.
This is an intelligent way of routing. In this method administrator configure router with a routing protocol such a way that the protocol discovers about other routers and its routes (Routers exchange routes). Even a new network added or removed router update their routing table each other.
Advantages of Dynamic Routing
- Automated process, routers update routing table each other hence less manual effort.
- Reroute traffic while current route is down or congested.
- Better uptime and Performance: Because of intelligence, routing protocol can react faster.
- Less administration task: As the network grows, the administrator doesn’t have to worry about configuring all the other routers on the network. Since the routers exchange the routes even if you added or removed a network.
Dynamic Routing is achieved via Dynamic Routing Protocols. There are different types of dynamic routing protocols in Cisco.
RIP (Routing Information Protocol):
RIP is an open source protocol, means it is compatible with routers other than Cisco. RIP is the simplest and easiest routing protocol to configure. RIP utilizes ‘hop count‘ as metric to decide the best path among two locations. Two variations of RIP are RIP Version 1 and RIP Version 2. Applicable to small networks having less than 15 hops.
OSPF (Open Shortest Path First):
It is also an Open source protocol. OSPF is the most popular dynamic routing protocol which is used today. It detects best route based on ‘Cost’ as it’s metric. OSPF is a full-featured routing protocol and applicable to any size of network.
IGRP (Interior Gateway Routing Protocol):
IGRP is a classful routing protocol; it assumes all the elements in a given network belong to same subnet. It is a distance vector protocol developed by Cisco. IGRP was designed to overcome the limitations of RIP (maximum hop count of only 15, IGRP supports a maximum hop count of up to 255). Best route is calculated by bandwidth, reliability, load and delay.
EIGRP (Enhanced Interior Gateway Routing Protocol):
This also a distance vector protocol designed exclusively for Cisco devices. Like OSPF, EIGRP is a full-featured routing protocol. Here the best route calculated by a formula that contains bandwidth, reliability, load and delay of the link. IGRP replaced by EIGRP. EIGRP is a classless routing protocol.
These are the Cisco routing protocols summary, We will cover Cisco routing protocols tutorial one by one together with how to configure Cisco routing protocols in upcoming articles.
Now let me know this CCNA quick reference guide helpful for you? Please share your comments below.