RIP Version2

The characteristics of RIPv2 are as follows:
  • RIPv2 is Distance-vector protocol which uses well-known UDP port number 520. RIPv2 is Classless protocol and supportsVLSM or CIDR, however, RIPv2 also behaves classful if auto-summarization is enabled.
  • Metric is router hop count. Metric/Hop Count increases when update is received on inbound interface and not when it exits via outbound interface.
  • Maximum hop count is 15; unreachable routes have a metric of 16.
  • RIPv2 sends Periodic route updates broadcasted every 30 seconds.RIPv2 uses Multicast addresses at both Layer 2 (01:00:5e:00:00:09) and Layer 3 (224.0.0.9) for advertising.
  • RIPv2 can advertise 25 routes per RIP message.
  • RIPv2 Implements split horizon with poison reverse.
  • RIPv2 can also generate triggered updates using interface level command "R1(config-if)#ip rip triggered"
  • RIPv2 supports authentication. Kindly read article RIPv2 Authentication for more details.
  • Default Administrative distance for RIPv2 is 120.
  • It Used in small, flat networks or at the edge of larger networks.

Enabling RIPv2 on a router along with disabling auto-summarization

R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#no auto-summary
R1(config-router)#



RIPv2 Packet Format:
  • Command: Indicates whether the packet is a request or a response message. The request message asks that a router send all or a part of its routing table. Response messages contain route entries. The router sends the response periodically or as a reply to a request.
  • Version: Specifies the RIP version used. It is set to 2 for RIPv2 and set to 1 for RIPv1.
  • AFI: Specifies the address family used. RIP is designed to carry routing information for several different protocols. Each entry has an AFI to indicate the type of address specified. The AFI for IP is 2. The AFI is set to 0xFFF for the first entry to indicate that the remainder of the entry contains authentication information.
  • Route tag: Provides a method for distinguishing between internal routes (learned by RIP) and external routes (learned from other protocols). You can add this optional attribute during the redistribution of routing protocols.
  • IP address: Specifies the IP address (network) of the destination.
  • Subnet mask: Contains the subnet mask for the destination. If this field is 0, no subnet mask has been specified for the entry.
  • Next hop: Indicates the IP address of the next hop where packets are sent to reach the destination.
  • Metric: Indicates how many router hops to reach the destination. The metric is between 1 and 15 for a valid route or 16 for an unreachable or infinite route.
R1#show ip protocols
Routing Protocol is "rip"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Sending updates every 30 seconds, next due in 13 seconds
  Invalid after 180 seconds, hold down 180, flushed after 240
  Redistributing: rip
  Default version control: send version 2, receive version 2
    Interface             Send  Recv  Triggered RIP  Key-chain
    FastEthernet1/0       2     2
    Loopback0             2     2
  Automatic network summarization is not in effect
  Maximum path: 4
  Routing for Networks:
    10.0.0.0
  Routing Information Sources:
    Gateway         Distance      Last Update
    10.10.12.2           120      00:00:06
  Distance: (default is 120)


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