Introduction To Routing Protocols

Introduction to Routing Protocols

What are protocols? The same set of rules and regulations for the communication between two different machines the same layer level.

What is Routing?

To route, a router needs to know: Destination Address Source it can learn from Possible Routes Best Route Maintain and Verify routing information

Routing Types Static Routing: Uses a route that a network administrator enters into the router manually.

Dynamic Routing: Uses a route that a network routing protocol adjusts automatically for topology or traffic changes.

Default Routing: Uses a route that allows a stub network to reach all known networks against it.

Static Routing Example Stub network 172.16.1.0 Network

so 176.16.2.2

172.16.2.1

Ip route 172.16.1.0 255.255.255.0 172.16.2.1 This a unidirectional route. You must have a route configured in the opposite direction.

Default Routing Example Stub network 172.16.1.0 Network

so 176.16.2.2

ip route 0.0.0.0

172.16.2.1

0.0.0.0

172.16.2.2

This route allows a stub network to reach all known networks beyond router A.

Protocol Types

Routing Protocols Routed Protocols

Routing Protocols Routing protocols are used between routers to determine paths and maintain routing tables. Examples:

RIP EIGRP OSPF Once the path is determined a router can route a routed protocol.(i.e. IP,IPv6)

Administrative Distance I need to send a packet from Router A to Router D.

Interface 128.31.7.1 Administrative Distance=100

Both router B and C will get it there. Which route is more reliable? Router A

Interface 128.5.1.3 Administrative Distance=120

Router C

Router B

Router D

e.g. RIP “AD-120” & IGRP “AD-100”

Autonomous System: Interior or Exterior Routing Protocols IGPs : RIP, IGRP

Autonomous System 100

EGPs :BGP

Autonomous System 200

•An autonomous system is a collection of networks under a common administrative domain •IGPs operate within an autonomous system •EGPs connect different autonomous systems

Classes of Routing Protocols B

Distance Vector

A

C D

Hybrid Routing

B A

C D

Link State

Distance Vector Network Discovery 10.1.0.0 E0

10.2.0.0 A

S0

Routing Table 10.1.0.0

E0

0

10.2.0.0

S0

10.3.0.0 10.4.0.0

S0

10.3.0.0 B

S1

Routing Table

10.4.0.0 S0

C

E0

Routing Table

0

10.3.0.0

S0

0

0

10.2.0.0 S0 10.3.0.0 S1

0

10.4.0.0

E0

0

S0

1

10.4.0.0 S1

1

10.2.0.0

S0

1

S0

2

10.1.0.0 S0

1

10.1.0.0

S0

2

• Routers discover the best path to destinations from each neighbor

Link-State Network Discovery Y

X

W A

E0

S1

Routing Table

B

S1

S0

Routing Table

Z S1

C

E1

Routing Table

E0W

0

S1X

0

S1Y

0

S1X

0

S0Y

0

E1Z

0

Topological Database

SPF Tree

SPF A Routing Table

Topological Database

SPF Tree

SPF B Routing Table

Topological Database

SPF Tree

SPF C Routing Table

• Routers calculate the shortest path to destinations in parallel

Hybrid Routing Choose a routing path based on distance vectors Balanced Hybrid Routing Converge rapidly using change-based updates

• Share attributes of both distance-vector and link-state routing

Thank You!