RIP2 (Routing Information Protocol)

Team Agile

Routing Protocols

Link State– OSPF– ISIS

Distance vector– RIP (version 1 and 2)– IGRP (Cisco Proprietary)

RIP

Interior Gateway Protocol Oldest Distance Vector Routing Protocol still

in use Based on Bellman-Ford algorithm 1982 in BSD UNIX (4.2) Classful Routing protocol Designed for Modest size network

RIP

Only best route is maintained (Route with lowest metric value)

Number of hops as metric No Authentication

RIP Updates

Sends Periodic Update and when topology changes (about 30 sec)

Updates are sent to all the neighbor Sends Complete Routing table Slow convergence (Router typically waits for

about 180 sec (6*30) to declare neighbor unavailable)

Response / Update message

RIP Message types

Request Message– Command 1– Specific Query about one or multiple address– If requested IP is 0.0.0.0 that mean Requesting complete

Routing table Response Message

– Command 2– Unsolicited response (regular updates)– Triggered Updates – Build in response to Request

Count to infinity

A B C D

1

2 3

4

Router B sends complete (including information which it learned from router C) routing table to Router C

In case of failure of link between C and D Router C will still think it can reach Router D via router B

This will cause routing loop and traffic will be bouncing between Router B and C

Split Horizon

Eliminate routing loops Used to eliminate count to infinity problem The updates received on interface 1 will not

be advertised back on the same interface– Router B will not send the information back to C

learned from C– In case of failure between C and D. Router C will

declare the Router Dead and Network 4 unreachable

RIPv2

Classless Multicast address for sending updates Authentication Triggered updates Backward compatible Split Horizon with Poisoned Reverse

– Router will send advertisement with metric value of 16 (unreachable)

RIPv2 Authentication

Per message Authentication Only one Authentication type (Clear text

password) First router entry Address family identifier

should be FFFF to tell the receiving end that first entry is password

If password is small then given length, it is padded with nulls (000..0)

RIPv2 Packet Format

Packet details

Address Family Identifier– Used to identify which

Route tag– Preserve externally advertised metric

IP address– IP address of the Destination network

Subnet mask– Subnet mask of the advertised network

Next hop– Immediate next hop IP to which the router will forward the

packets for destination

RIPv2 Compatibility with RIPV1

Fully compatible Compatibility Switch required

– To disable use of Multicasting on outgoing messages

When using RIP1 and RIP2 in network, a single subnet mask should be used, to avoid routing black holes

References

RFC 1058http://www.ietf.org/rfc/rfc1058.txt

RFC 2453http://tools.ietf.org/html/rfc2453

Routing Information Protocol http://

www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/rip.htm

Q & A