RIP2 (Routing Information Protocol)

1
RIP2 (Routing Information Protocol)

• Team Agile

2
Routing Protocols

• Link State
• OSPF
• ISIS
• Distance vector
• RIP (version 1 and 2)
• IGRP (Cisco Proprietary)

3
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

4
RIP

• Only best route is maintained (Route with lowest
  metric value)
• Number of hops as metric
• No Authentication

5
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 (630) to declare neighbor
  unavailable)

6
Response / Update message
7
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

8
Count to infinity

• 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

9
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
  

10
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)

11
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)

12
RIPv2 Packet Format
13
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

14
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

15
References

• RFC 1058
• http//www.ietf.org/rfc/rfc1058.txt
• RFC 2453
• http//tools.ietf.org/html/rfc2453
• Routing Information Protocol
• http//www.cisco.com/univercd/cc/td/doc/cisintwk/i
  to_doc/rip.htm

16
Q A