What is Wildcards? Wildcard Configuration on OSPF Network

By | 9th November 2015

OSPF Network Wildcard Configuration Example.

How to use Wildcards in OSPF Configuration.

    The main focus in this example is on wildcards. We will look at how to configure OSPF on a network using wildcards.

We will use the topology diagram below as a sample network.

wildcards config



Let begin with the HQ router, the IP address assigned to the FastEthernet0/0 is 192.168.20.33 /27. The slash notation (/27) means that the subnet mask is 255.255.255.224.

 As been explained earlier on the Wildcard page, subtract the above mask from 255.255.255.255.This will result to 0.0.0.31 which will be your wildcard for Fa0/0 of the HQ router!

For the serial interface, use the same method; /30 means 255.255.255.252 as mask, then subtract this from 255.255.255.255,

The result will be 0.0.0.3

The Configuration on HQ router will look like this:

HQ#config t

HQ(config)#router ospf 9

HQ(config-router)#network 172.17.10.32 0.0.0.31 area 0

HQ(config-router)#network 10.10.11.8 0.0.0.3 area 0

BR1(config-router)#network 10.10.11.0 0.0.0.3 area 0

HQ(config-router)#end

HQ#

 The Configuration on BR1:

BR1#config t

BR1(config)#router ospf 9

BR1(config-router)#network 172.17.10.16 0.0.0.15 area 0

BR1(config-router)#network 10.10.11.0 0.0.0.3 area 0

BR1(config-router)#end

BR1#

 BR2 Configuration:

BR2#config t

BR2(config)#router ospf 9

BR2(config-router)#network 172.17.10.64 0.0.0.63 area 0

BR2(config-router)#network 10.10.11.8 0.0.0.3 area 0

BR2(config-router)#end

BR2#

When configuring EIGRP, OSPF, and ACLs, you will need your wildcards. To do this properly, you must look at the IP address and the slash notation “/ ”. This will help you to figure out the subnet, mask, and wildcard.

How to Configure ACLs using Wildcard

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