From: Tom Young (gitsyoung@xxxxxxxxxxx)
Date: Wed Jul 17 2002 - 20:52:33 GMT-3
Shuyi:
Your description about the bandwidth and cost was
right. But I want to know the metric, and the relevance
about metric and cost.
Thanks
Tom
--- Brian McGahan <brian@cyscoexpert.com> $B$+$i$N%a%C%;(B
$B!<%8!'(B
> Shuyi,
>
> The "bandwidth" value of a link doesn't have
> anything to do with
> the physical bandwidth of the interface. For
> example, a serial
> interface on a 2500 series router has a bandwidth
> *value* of 1544 Kbps.
> This does not reflect that these interfaces can
> physically support up to
> 2Mbps or 4Mbps, and whether or not you have a
> 256Kbps frame-relay
> circuit attached to it. The "bandwidth" value of an
> interface is
> static, and is set using the interface "bandwidth"
> command.
>
> OSPF computes it's cost value by taking
> (ReferenceBandwidth /
> InterfaceBandwith) ReferenceBandwidth has a default
> value of 10^8 bps,
> or 100Mbps. Therefore a 100Mbps FastEthernet
> interface has a cost of 1.
> The reference bandwidth value can be changed with
> the OSPF command "
> auto-cost reference-bandwidth X" where X is the
> reference bandwidth in
> terms of Mbits per second. If you want a Gigabit
> link to have a cost of
> 1, the reference bandwidth should be 1000.
>
> HTH
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> http://www.cyscoexpert.com
> Voice: 847.674.3392
> Fax: 847.674.2625
>
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> Shuyi Li
> Sent: Wednesday, July 17, 2002 1:20 PM
> To: Jason Sinclair
> Cc: 'Tom Young'; ccielab@groupstudy.com
> Subject: RE: OSPF 's cost and metric
>
> Jason,
>
> Regarding the OSPF metric, I have a question for you
> that, the cost of
> links is considered to be the current available BW,
> or just the total BW
>
> even it's being occupied, say 50%. Please advise.
>
> thanks in advance.
> /shuyi
>
>
> At 05:22 PM 7/17/2002 +1000, Jason Sinclair wrote:
> >Tom,
> >
> >In OSPF the metric is the cost. What I mean here is
> best clarified as
> >follows:
> >
> >1. In RIP the metric as we know is hop count.
> >2. EIGRP/IGRP use a composite metric based on
> things such as bandwidth,
> >delay, etc
> >3. In OSPF the metric is based on the cost of
> links. The lower the cost
> the
> >more preferred the path
> >
> >Hope this makes sense.
> >
> >Regards,
> >
> >Jason Sinclair CCIE #9100
> >Manager, Network Control Centre
> >POWERTEL
> >55 Clarence Street,
> >SYDNEY NSW 2000
> >AUSTRALIA
> >office: + 61 2 8264 3820
> >mobile: + 61 416 105 858
> >email: sinclairj@powertel.com.au
> >
> >-----Original Message-----
> >From: Tom Young [mailto:gitsyoung@yahoo.co.jp]
> >Sent: Wednesday, 17 July 2002 16:35
> >To: ccielab@groupstudy.com
> >Subject: OSPF 's cost and metric
> >
> >Hi, group.
> >
> > The OSPF's "cost" and "metric" parameters made
> me
> >confused. Who can clear it for me?
> >
> >
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