Back to RIP Guide RIPv2 configuration

RIP Configuration Commands and Internal Tables

Deploying RIPv2 in a network environment requires precise command execution so classless masks are honored, interfaces are selected correctly, and loop-prone backup paths stay out of the active routing table.

RIPv2 Network Statement No Auto-Summary RIP Database RIB

RIP Configuration Commands and Internal Tables: Quick Summary

RIPv2 is enabled globally with router rip, forced into classless operation with version 2, and protected from classful boundary summarization with no auto-summary. The network command uses major classful boundaries, but the actual interface subnet is what gets advertised. Internally, RIP stores candidate paths in its own database before the best route is selected for the IP routing table.

Routing process router rip
Version control version 2
Classless behavior no auto-summary
Default RIP AD 120

RIP Configuration Commands and Internal Tables: Table of Contents

  1. Step-by-Step Initializing Commands
  2. Mechanics of the Network Statement
  3. RIP Database
  4. IP Routing Table and RIB Selection

Section 2: Deep-Dive Command Syntax and Multi-Interface Behavior

To activate the routing process globally and bring RIP up to classless standards, execute the following command block.

Router - Initialize RIPv2

Router> enable
Router# configure terminal

! Initialize the global routing instance inside memory
Router(config)# router rip

! Force the processor to use classless v2 features and multicast
Router(config-router)# version 2

! Disable automatic classful fallback boundary matching
Router(config-router)# no auto-summary
  • router rip: Starts the RIP process and moves the router into RIP configuration mode.
  • version 2: Enables RIPv2 behavior, including classless route advertisements and multicast updates.
  • no auto-summary: Prevents automatic classful summarization at major network boundaries.

1. The Mechanics of the Network Statement

The network command in RIP behaves differently than in protocols such as OSPF. RIP expects the major classful network boundary, even when the actual interface uses a more specific subnet mask.

Router - Advertise RIP Networks

Router(config-router)# network 10.0.0.0
Router(config-router)# network 192.168.1.0
Classful requirement: Declare the major classful network boundary, such as 10.0.0.0, even if the router interface is configured as 10.1.5.1/24.

When you enter a RIP network statement, two actions happen at the same time:

  • Interface activation: RIP scans the router for physical interfaces whose IP addresses fall within that major network block, then begins sending and receiving RIP updates on those ports.
  • Route advertisement: The specific subnet assigned to the matched physical interface is bundled into outbound RIP packets and advertised to neighbors.

Section 3: Internal Table Architecture - RIB vs. RIP Database

A common mistake is assuming the active routing table is where RIP does all of its calculation. RIP maintains a separate protocol database before the best routes are handed to the routing table.

1. The RIP Database

The RIP database, viewed with show ip rip database, acts as the raw storage repository for the protocol. Every route update that enters UDP port 520 from any neighbor is collected and logged here.

Path redundancy: If three neighbors advertise a path to the same target network, all three candidate paths can be stored in the RIP database, even if some have poor hop counts.

Router - RIP Database Output

Router# show ip rip database
10.0.0.0/8    auto-summary
10.1.1.0/24   directly connected, GigabitEthernet0/0
192.168.5.0/24
    [2] via 192.168.12.2, 00:00:18, GigabitEthernet0/1
    [4] via 192.168.13.3, 00:00:05, GigabitEthernet0/2

In this example, RIP knows two ways to reach 192.168.5.0/24. One path is 2 hops away through 192.168.12.2, and the backup path is 4 hops away through 192.168.13.3.

2. The IP Routing Table and RIB

The Routing Information Base (RIB), viewed with show ip route rip, is the official forwarding decision table. It only contains the best selected paths after the router compares candidate routes.

  • Selection process: The RIP engine scans the internal RIP database, extracts the entry with the lowest hop count, and passes that route to the RIB.
  • Administrative distance: If no other routing protocol has a lower AD to that destination, the RIP path is installed with an administrative distance of 120.

Router - RIP Routes in the RIB

Router# show ip route rip
R    192.168.5.0/24 [120/2] via 192.168.12.2, 00:00:18, GigabitEthernet0/1
Analysis: The 4-hop path remains out of the active routing table. The router installs the preferred 2-hop route to optimize lookup behavior and reduce loop risk.