Introduction Open Shortest Path First (OSPF) is a link state protocol that has been around for a long time. It is geneally well understood, but design considerations often focus on the maximum number of routers in an area. What other
OSPF – Non Broadcast and Point to Multipoint
Introduction There was a discussion on a forum about the point to multipoint network type in OSPF. What is the purpose of it and why are /32 endpoints advertised? To understand the solution we must first understand the problem. This
Some pointers on OSPF as PE to CE protocol
There was a discussion at the Cisco Learning Network (CLN) about OSPF as PE to CE protocol. I wanted to provide some pointers on using OSPF as PE to CE protocol. RFC 4577 describes how to use OSPF as PE
Default routes in BGP
I have seen in forums and in other places that some find that the default route in BGP is a bit confusing. There are multiple ways of orginating a default route in BGP. To start this is the topology used:
Why OSPF FA is only set on broadcast networks
A friend of mine asked me about the OSPF forwarding address. The question was why must the network type be broadcast for the FA to be set? Why is not point to point and point to multipoint network type valid?
Tiebreakers with routes from different OSPF processes
This post is inspired by a discussion at Twitter with Ivan Pepelnjak and Nicolas Michel. Nicolas asked what happens when there is the same route from two different OSPF processes. Which one will be selected? Ivan explained how to use
ASBR in NSSA – Choosing what IP to use as forwarding address
OSPF is one of the protocols where the details are very important. It has lots of bits and pieces to make it run in a proper way. I have described the forwarding address in an earlier post and this time
INE 10 day bootcamp – Review
I’m back from London and it’s been a great experience. Many readers are interested in what the bootcamp is like. It is a big investment to go for so it is understandable that you want to know if it will
Route redistribution – Route-maps and tagging
Earlier I have done some posts on route redistribution and on route filtering in different protocols. I wanted to expand on this by showing different ways we can tag and do filtering with route-maps when doing route redistribution. We start
OSPF – Use of forwarding address
In OSPF and other routing protocols we have something called forwarding address. This can be used to route traffic in another direction than to the router that originated the LSA. We start with the following topology. It’s a basic OSPF