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RE: auto-cost reference-bandwidth posted 08/03/2006
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Thx. I see now. The reason why my lab book wanted me to use 20000 was
because they where looking for a specific cost on the interfaces. 

 

  _____  

From: Shanky [mailto:shankyz@xxxxxxxxx] 
Sent: Thursday, August 03, 2006 9:33 AM
To: Robert Jones
Cc: Elias Chari; ccielab@xxxxxxxxxxxxxx
Subject: Re: auto-cost reference-bandwidth

 

Hi Robert,

 

by default auto-cost reference-bandwidth for OSPF is 100. This means a link
with 100  Mbps bandwidth will have a cost of 1.

 

Now if we want a gig link to have a cost of 1, the auto-cost
reference-bandwidth is 1000

 

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cr/hirp_r
/rte_osph.htm#wp1089647

you can test it , bt specifying different bandwidth values on an interface
and making corresponding changes to auto-cost.

 

So the easy way to calculate is ..it is the value in MB which should have a
cost of 1, so if u want a 10gig link to have a cost of 1, auto-cost
reference-bandwidth is 10000.

 

Hope it helps

 

Shanky

On 8/3/06, Robert Jones <trevelle@xxxxxxxxxx> wrote: 

So I take it that the options for MBITS (20000) used with command is
irrelevant.  R4(config-router)#Auto-cost REference-bandwidth 20000. 



Thx.

_____

From: Elias Chari [mailto:elias.chari@xxxxxxxxx]
Sent: Thursday, August 03, 2006 9:03 AM
To: trevelle@xxxxxxxxxx  <mailto:trevelle@xxxxxxxxxx> 
Cc: ccielab@xxxxxxxxxxxxxx
Subject: Re: auto-cost reference-bandwidth



There is no method...it's a design decision. The router uses this value to
calculate the interface cost as opposed to the default. 



In a production network all routers should be configured with the command,
in the ccie lab who knows...-)



Rgds

Elias






On 8/3/06, trevelle@xxxxxxxxxx < trevelle@xxxxxxxxxx
<mailto:trevelle@xxxxxxxxxx> > wrote:

I understand that the auto-cost refernce-bandwidth command is used for 
interface that are greater than 100 mbs so that you can have the correct
cost associated with that interface. My question is what method is used to
come up with the MBITS per second when using the auto-cost reference 
bandwidth  command.


R4(config-router)#AUto-cost REference-bandwidth ?
<1-4294967>  The reference bandwidth in terms of Mbits per second

Thx in advance.

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