[168393] in North American Network Operators' Group
RE: OSPF Costs Formula that include delay.
daemon@ATHENA.MIT.EDU (Erik Sundberg)
Fri Jan 24 15:27:01 2014
From: Erik Sundberg <ESundberg@nitelusa.com>
To: Randy <randy_94108@yahoo.com>, "nanog@nanog.org" <nanog@nanog.org>
Date: Fri, 24 Jan 2014 20:26:39 +0000
In-Reply-To: <1390532559.26143.YahooMailNeo@web181703.mail.ne1.yahoo.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
I understand OSPF default calculation for cost doesn't include delay. I am =
looking for a formula that I can use to manually set the OSPF costs that fa=
ctors in delay.
When using OSPF's default costs, the shortest path is not always the optima=
l path.
Example
New York to Los Angeles. Assuming all links are the same bandwidth and have=
a ospf cost of 1.
Path 1 (75ms) - OSPF Cost 2 - New York > Dallas > Los Angeles
Path 2 (65ms) - OSPF Cost 3 - New York > Chicago > Denver > Los Angeles
If I left the default cost's alone then path 1 would win because it has a l=
ower ospf cost, however it take traffic 10ms longer to get there.
However I would like traffic to take Path 2 by adjusting the OSPF cost.
I am looking for a formula that other people are using .p
Thanks
Erik
-----Original Message-----
From: Randy [mailto:randy_94108@yahoo.com]
Sent: Thursday, January 23, 2014 9:03 PM
To: Erik Sundberg; nanog@nanog.org
Subject: Re: OSPF Costs Formula that include delay.
----- Original Message -----
> From: Erik Sundberg <ESundberg@nitelusa.com>
> To: "nanog@nanog.org" <nanog@nanog.org>
> Cc:
> Sent: Thursday, January 23, 2014 4:47 PM
> Subject: OSPF Costs Formula that include delay.
>
> What is everyone using for an OSPF cost formula that factors in a
> circuits delay and bandwidth (10M-100G)???
>
> Thanks in advance
umm..are you sure your question is not about EIGRP?
OSPF has no concept of interface-delays.
The default reference bandwidth for OSPF is 100M
In your case if you set your reference bandwidth to 100000 your 100G links =
would have a link cost of 1, 10G - 10, 1G-100, 100M-1000 and 10M-10000
A vendor specific list would be a better place to ask.
./Randy
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