Subjects Covered On Monday 12/11/07

OSPF

When changing an interface from one area to another, if you change this under the routing process, ensure that there isn’t an”ip ospf 1 area (id)” command under the interface as this command takes precedence over the “network” command.  Under the routing process everything will look correct, under the output of “show ip ospf interface brief” you will see that the interface you wanted to change to another area will still show up as the old area and adjacencies won’t come up.

When mutual redistribution is occuring in a hub and spoke environment and the spokes are redistributing, to filter selected routes via AD use the following command:

access-list 1 permit 155.1.23.0 0.0.0.255
access-list 1 permit 155.1.37.0 0.0.0.255
access-list 1 permit 150.1.33.0 0.0.0.255
access-list 1 permit 150.1.3.0 0.0.0.255
!
distance 180 150.1.1.1 0.0.0.0 1

The IP address in the command is the RID of the router that is advertising the route in.  This will be the RID of the ASBR. 

I kept placing the RID of the hub and wondered why I was still seeing the routes as an E2 and not learned from RIP.  Look in the ospf database and look at the IP under the “ADV Router” column to see which IP address you need to specify in the above command.
Also, before the command goes on, ensure you look on both routers routing tables to see the E2 routes that you want to match.

 Also look at the Connected interface on each router that is part of the RIP domain, remember this will also show as an E2 route (as well all other RIP routes) when redistributed so make sure you take that into consideraton when viewing which routes to change the AD of.

Also started to cover some QoS as this is a weak subject of mine.

Amount of time studying today – 4hrs 50 mins
Total Studying hours so far since starting this blog – 32hrs 58 mins