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RIP and OSPF Routing Protocols

This document discusses several routing protocols, including RIP and OSPF. RIP is an older distance-vector routing protocol that uses hop counts as its routing metric. It has a maximum hop count of 15 and converges slowly using the Bellman-Ford algorithm. RIP periodically sends routing updates every 30 seconds. OSPF is a newer link-state routing protocol that converges faster than RIP using Dijkstra's algorithm. It floods link state advertisements throughout an autonomous system to build an accurate topology map at each router. OSPF encapsulates its advertisements directly in IP packets rather than using UDP or TCP. It also supports authentication to restrict rogue routers.

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Aayushi Singh
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111 views30 pages

RIP and OSPF Routing Protocols

This document discusses several routing protocols, including RIP and OSPF. RIP is an older distance-vector routing protocol that uses hop counts as its routing metric. It has a maximum hop count of 15 and converges slowly using the Bellman-Ford algorithm. RIP periodically sends routing updates every 30 seconds. OSPF is a newer link-state routing protocol that converges faster than RIP using Dijkstra's algorithm. It floods link state advertisements throughout an autonomous system to build an accurate topology map at each router. OSPF encapsulates its advertisements directly in IP packets rather than using UDP or TCP. It also supports authentication to restrict rogue routers.

Uploaded by

Aayushi Singh
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Routing Protocols

Prof. Ayaskanta Mishra


Internet Structure
Hierarchical Routing
Autonomous System
Routing Information Protocol (RIP)
• DV Algorithm
• Periodic Updates
Bellman Ford Algorithm/ Equation
RIP (Mathematics)

• distance vector algorithm set of rules


Software implementation

included in BSD-UNIX Distribution in 1982


distance metric: # of hops (max = 15 hops)
A RIP
can allow
maximum
15 hops

More than
15
infinite
Hop counts in RIP
Forwarding Tables

R1 R2 R3
App

RIP Implementation
Transport Routing Protocols (RP) --> TCP/IP (Complete) --> Software solution
Network Info about Routes
Data-Link
Physical Cost. Link,
Providing Service to the Network Layer --> Routing informatics
Shortest path
UNIX
Environment

Database
OS

Process

Daemon

Routing
Table
RIP Messages

Decimal --> Binary --> HEX


HEX-CODE
RIP Request/ Response
RIP has two types of messages:
1. Request ( Sent by Router)
2. Response

Request:
1. Sent by router when a new Router come online
2. Router has time-out entries
3. Request message can ask about specific entries or all entries
Response:
1. Response Message (update) can be either solicited or unsolicited
response message
2. Solicited response message message is sent only in answer to a
request message, It contains destination specific information
corresponding to request
3. Unsolicited message sent periodically every 30 seconds when
there is a change in forwarding Table
RIP Algorithms
DV --> B_F Algorithm

The value is comming from the


neighbour
RIP Performance
15 x 15 Max. 15 iterations ---> Convergence
RIP Zone_3
Zone_2
Zone_1
15 Max
15 15 Max
Matrix Max

15 hops

15 hops
Open Shortest Path First (OSPF)
• Link State Algorithm
• Convergence is faster
Global
Centralized

• Flooding
All Routing Table updates ---> Flooding
N iterations
Dijkstra's Algorithm Routing Table is Advertised to ALL NODES

1. “open”: publicly available


LS Algorithm

2. uses Link State algorithm


Network

3. LS packet dissemination
AS- Autonomous System

4. topology map at each node


5. route computation using Dijkstra’s algorithm
6. OSPF advertisement carries one entry per neighbor router
7. advertisements disseminated to entire AS (via flooding)
8. carried in OSPF messages directly over IP (rather than TCP
or UDP
OSPF Encapsulated
in IP payload
IP Payload
Header
D1
S D S D2
Unicast Broadcast
Multicast D3

Load-Balancing

DTRC

Flooding (AS)
Forwarding Tables
OSPF Areas
Areas in AS
Link State Advertisements
AS1 AS2

Five different LSPs


1
2 Ar0 Ar0
3
OSPF Implementation

Latest Version

Protocol (89) Encapsulated

IP Datagram IP Header Payload


( 20 ~ 40 bytes)
u z w

OSPF Message Format


R1 R2
v x
Network Security

Authentication & OSPF Algorithm


Authentication Encryption

Authentication:
•OSPF Common header has provision for authentication
•It restrict rouge routers to participate
OSPF Performance

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