[c-nsp] OSPF VS ISIS

[Wayne Xiao]

To achieve fast convergence after a link or router failure, your network
need to be able to detect the failures quickly and react to it quickly.
Strike a balance between recovery speed and network stability. The OSPF
default value is way too conservative/slow.

Some techniques I used in my network to achieve fast convergence:

1. use ether-channel. If one physical link down, no convergence happen
2. design network to have 2 equal cost routes over 2 links, if one link
down, 0 second converge time
3. For router to router connection, use direct cable connection as
possible as I can. If a link fails, 0 second to detect it. 
4. For Ethernet and above speed connection, configure OSPF keepalive
timer to sub-second (if it's not WAN link).
5. tune the OSPF timer:
	timers throttle spf 10 100 5000
	timers throttle lsa all 10 100 5000
	timers lsa arrival 80






-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Vincent De
Keyzer
Sent: 27 February 2006 13:46
To: 'Oliver Boehmer (oboehmer)'
Cc: cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] OSPF VS ISIS


> But in a properly designed network, both protocols can converge in 
> sub-second..

My OSPF network is far from converging sub-second (so according to you
it is far from being properly designed - fine, I can take criticism :)

First of all, link failure on Ethernet links takes 30 to 40 seconds to
detect... is there anyway to speed this up?

Then, even after failure detection, I have the feeling it still takes 3
to 5 seconds to converge...

What am I doing wrong?

Vincent

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