Ethernet Switches & Routers

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New Contributor
Posts: 3
Registered: ‎08-23-2016
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auto-cost reference-bandwidth command (OSPFv2)

In all documentation I can find on the Brocade site, Everything seems to indicate that the defualt reference bandwidth is 100 Mbps. Is this really correct? This would mean that a 100Mb link is treated the same cost in OSPF as my two 40Gbps LAG links. I would say that the traffic should definately try to take the faster 80Gig link as opposed to the 100Meg or 1 Gig links. But this seems to suggest they will see both these links at a cost of 1 for directly connected links like this. I am thinking of setting this auto-cost Reference-bandwidth to something around 400,000 network wide. This involves changing around 100 routers on my campus. I want to ensure I am reading the documentation correctly though before I do this. It seems to be the case when I run the cost metrics in the CLI on my routers though. All the costs are very low (single digits) all around campus regardless of their speeds. I would think I would want to change this moving forward though as we deploy the 40 Gig Fabric links and enable routing through the fabric. I want those faster links to look more desirable correct? 

Brocade Moderator
Posts: 100
Registered: ‎02-04-2015

Re: auto-cost reference-bandwidth command (OSPFv2)

Hello Brandon,

 

Please find answers inline to your questions.

 

1) In all documentation I can find on the Brocade site, Everything seems to indicate that the defualt reference bandwidth is 100 Mbps. Is this really correct?

 

Yes. Meaning that all link faster than 100M are equal in cost.

 

2) I would think I would want to change this moving forward though as we deploy the 40 Gig Fabric links and enable routing through the fabric. I want those faster links to look more desirable correct?

 

This is true. Although 400,000 (i.e 400G) seems a bit steep.

 

As you mentioned, you will need to apply the new reference to all OSPF routers.

 

Hope this helped addressing your concerns

 

Regards,

Os

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