June 11, 2010

OSPF Flood Reduction

By default OSPF floods its domain with LSAs every 30 mn, that is half of the Max-Age time which is of 1h to ensure that the LSA database across all routers of the domain are in sync and the network is properly converged. While this acts as good failsafe in case LSA’s are dropped and LS databases across downstream routers become inconsistent when topology changes occur, it is reasonable on stable networks, to completely disable the LSA scheduled updates and only propagate LSA updates only once the network topology changes. ... Read more

May 6, 2010

OSPF LSA Types

Following my blog post on OSPF BDR - DR election, I have received various questions regarding OSPF and thus I decided to write a small excerpt to describe the type of LSAs generated whether it is in a stub area etc… Before I start, it is important to keep in mind, that LSAs are carried into OSPF packet 4 . Those OSPF packet 4 are referred as LSU (Link-State Update) and carries the router’s LSA (one or more). ... Read more

March 4, 2010

quaggOS 0.1a1 released - OSPF/BGP routing solution

Hi, I am pleased to announce that quaggOS in alpha version has been released. quaggOS is a live linux distribution I created which turns a server/pc into a full BGP/OSPF router. This is achieved by using the Quagga routing solution application. For more information, visit http://quaggOS.org To download and test the alpha release, click here

October 1, 2009

OSPF BDR DR election process

This post assumes that you have a basic understanding of OSPF… if not, I suggest jumping over http://en.wikipedia.org/wiki/OSPF for a first quick read. However for the sake of this post, I will go over some basic reminders. The “hello” packet The OSPF routers sends a periodic packet referred to as the hello packet ‘multicast 224.0.0.5’ which is composed of the OSPF header + different fields ID necessary for routers to neighbor and become adjacent. ... Read more