Totally Stub Area - OSPF Stubby Protocol

The default routes are used to communicate with other network in totally stub area. LSAs 3, 4 and 5 are not advertised in totally stub area, only the default summary routes are advertised in this area to reducing the routing table size and processor overhead also.

The main purpose of totally stub area is to block the flooding from LSAs 3, 4 and 5 advertisements in OSPF and only OSPF injects a default router into a totally stub area. In this tip we will discuss here only about totally stub area and the remaining area types will be discussed in the next tips.

Follow the network topology of three different routers in given figure:

In this example we will configure router B as a totally stubby. So we will be concerned here only with router B and then run simple ospf protocol on other A and C routers.

OSPF configuration on Router B as totally stubby area

In global configuration mode

Router-B(config) # router ospf 1 (Here 1 indicates the process identification number)

Router-B(config-Router) # network 20.0.0.0 0.255.255.255 area 1 (Here 20.0.0.0 indicates the network ID and 0.225.255.255 wildcard mask with area 1)

Router-B(config-Router) # network 30.0.0.0 0.255.255.255 area 0 (Here 30.0.0.0 indicates the network ID and 0.225.255.255 wildcard mask with area 0)

Router-B(config-Router) #area 1 stub no-summary (Here 1 indicate the area ID and area 1 is designated as totally stubby area)

Router-B(config-Router) #exit (exit from ospf 1 on router B)

OSPF configuration on Router A

In global configuration mode

Router-A(config) # router ospf 1 (Here 1 indicates the process identification number)

Router-A(config-Router) # network 210.100.10.0 0.0.0.255 area 1 (Here 210.100.10.0 indicates the network ID and 0.0.0.255 wildcard mask with area 1)

Router-A(config-Router) # network 20.0.0.0 0.255.255.255 area 1 (Here 20.0.0.0 indicates the network ID and 0.225.255.255 wildcard mask with area 1)

Router-A(config-Router) #exit (exit from ospf 1 on router A)

OSPF configuration on Router C

In global configuration mode

Router-C(config) # router ospf 1 (Here 1 indicates the process identification number)

Router-C(config-Router) # network 210.100.30.0 0.0.0.255 area 0 (Here 210.100.30.0 indicates the network ID and 0.0.0.255 wildcard mask with area 0)

Router-C(config-Router) # network 30.0.0.0 0.255.255.255 area 0 (Here 30.0.0.0 indicates the network ID and 0.225.255.255 wildcard mask with area 0)

Router-C(config-Router) #exit (exit from ospf 1 on router C)

Routing Information Protocol (RIP) Configuration

Interior Gateway Routing Protocol (IGRP) Configuration

COMPUTER TIPS