Re: speed command basics?

If you have two interfaces directly connected and set to different speeds
the link will not come up. If you have one side hard set and the other side
auto then speed will negotiate but duplex will not. For duplex to negotiate
then both sides must be set to Auto.

Duplex mismatches are one of the most common network issues and this is the
reason I advocate always using AUTO for speed and duplex. The really tricky
thing about duplex mismatches is they don't totally bring down a link but
cause collisions and errors, these increase under load. So often someone
can bring up a link, then run some pings across it and it appears fine. It
is only later when the link is under load and performance is terrible that
the problem becomes evident.

Hope that helps.

On Sun, Jun 2, 2013 at 10:10 AM, Cisco Fanatic <ebay_products_at_hotmail.com>wrote:

> This sounds basis but after trying different IOS version I am getting
> different results. It's better to understand from experts ...
>
> !
> interface GigaEthernet1/1
> speed 100
> duplex full
> !
>
> Will this interface only capable of supporting 100MB now?
> What if the traffic received on this Gig interface is 200MB will it get
> dropped?
> I have to control over the other side router, what if it's configure for
> auto/auto?
>
> Yuri
>
>
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-- 
Marc Abel
CCIE #35470
(Routing and Switching)
Blogs and organic groups at http://www.ccie.net