Re: OSPF Costs Formula that include delay.

[Bill Blackford <bblackford () gmail com>]

+1
On Jan 24, 2014 12:41 PM, "Owen DeLong" <owen () delong com> wrote:

> Some networks I have worked with took the average latency of each link and
> assigned that (with some constant multiple) as the interface cost.
>
> Of course this all fails miserably if you are using anything like MPLS
> underneath your OSPF.
>
> Owen
>
> On Jan 24, 2014, at 12:26 PM, Erik Sundberg <ESundberg () nitelusa com>
> wrote:
>
> > 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
> factors in delay.
> > When using OSPF's default costs, the shortest path is not always the
> optimal 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 lower 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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