BGP Link Bandwidth: Line Speed Question

[mhcraig]

I've been looking into BGP Link Bandwidth:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t2/ftbgplb.htm

One question I have is where do you set line speed? I don't see any references to where you manually set the bandwidth for each provider/interface. This implys that by activating BGP Link Bandwidth it automatically is configured or "knows" the line speed of each connection to each provider participating.

If you can't set the speed manually, it might be a problem with my situation. Can someone clarify?

Here is my situation:

We host sites/apps and are an endpoint soon to be connected to 2 ISPs. We are primarily implementing BGP for the purpose of fault tolerance. Each provider is running fiber to our NOC which is then converted to ethernet and physically handed off to us. One provider is allocating us the entire 100 Mbps the other will be hard capping us at 20 Mbps.

Our router won't know the difference between each connection I would assume. It will think both are FastEthernet at max speed. How can I tell BGP that this line is 100 and the other line is 20 and have Link Bandwidth proportionally even the load outbound. (I'm only really concerned about outbound traffic I might add.)

Our situation is basically this one:

Multihomed to Two ISPs Through a Single Local Router

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml#conf4

Does this make sense?

Thanks in advance,

Hutch

[Harold Ritter · Accepted solution]

The interface BW is used by BGP Link Bandwidth. In your scenario, you can set the BW (using the bandwidth command) to 20Mbps on the one interface rate-limited by the ISP and let the other default to 100Mbps.

Let me know if I answered your question,

[mhcraig]

Ahhhhh. I've never needed to use the interface bandwidth command before. I've always assumed it was more for "informational" purposes. Thanks so much - that will do the trick.

Hutch

[Harold Ritter]

You're welcome. Just as an FYI, the bandwidth command is also used by OSPF and Eigrp for the metric calculation.

Hope this helps,