IP Routing

1
IP Routing

• Kentaro Hayashi
• Graduate school of Information Science and
  Electrical Engineering
• Department of Advanced Information Technology
• Kyushu University

2
Contents

• Routing
• RIP
• OSPF

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Routing

• The process of selecting paths in a network along
  which to send network traffic.
• Routing table
• IP address the destination
• Metric the cost of the path through
• Next hop the IP address of the next router

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Routing table
172.16.100.0/24
.1
.2
172.16.251.0/24
.1
.1
.2
172.16.1.0/24
192.168.1.0/24
.1
.1
172.16.252.0/24
172.16.250.0/24
.1
.2
.1
172.16.50.0/24
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Routing table

• Static routing
• Dynamic routing
• Distance vector algorithms
• RIPIGRP
• Linkstate algorithms
• OSPF

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Dynamic Routing

• IGP (Interior Gateway Protocol)
• RIP (Routing Information Protocol)
• OSPF (Open Shortest Path First)
• EGP (Exterior Gateway Protocol)
• BGP (Border Gateway Protocol)
• ?AS (Autonomous System)

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RIP (Routing Information Protocol)

• The simple routing protocol
• Used in small network
• Distance vector algorithms
• IGP
• RFC 1058 (Charles Hedrick 1988)

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RIP

• RIP update
• In RIP, all router can request to send update
  information.
• Broadcast
• Every 30 seconds
• RIP metric
• The numbers of hop routers on path through
• 16 is infinity (15 is max)

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Convergence

• When the consistence of the network changed, RIP
  update is sent. And the phase which all routers
  in this RIP network received the RIP update is
  called Convergence.
• Update timer 30s
• Invalid timer 180s
• Flush timer 240s

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Default route

• Destination IP address is 0.0.0.0
• Next hop is upper router

172.16.0.0/16 20 Subnet
192.168.0.0/16 20 Subnet
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OSPF (Open Shortest Path First)

• Used in large network
• Link-state algorithms
• IGP
• Layer structure
• RFC 2328 (1998)

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Link-state algorithms

• All router has network information. It is called
  link state data base. And calculate the shortest
  path to all host, using Shortest Path First
  algorithm wrote by Dijkstra.

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Area
Backbone area
Area 1
Area 2
Area 3