Transmit Errors on Catalyst 2950

Unanswered Question
Jul 29th, 2009
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We have several Catalyst 2950 switches over multiple sites that are connected via a BT LES (fibre) 10Mb deditacted lines.

When looking at the port statistics for these lines they are showing multiple Transmit errors (at both ends of the connection), more specifically Total collisions and Late collisions.

I am trying to find out why this is and what we can do about it, as I'm sure it should not be happening.

These ports are all set to 10Mb half duplex.

Any advice gratefully received!

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jbrenesj Wed, 07/29/2009 - 08:19
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In a half-duplex link you will always see collisions. well, this is what half-duplex is all about don't you think?

As traffic increases, chances of getting collissions increment.

No way to avoid them unless moving to full duplex becuase the link will now have one way out and another way in.

Right now you are driving in a lane in which cars can come or go.... they'll crash

gavinwhalley Thu, 07/30/2009 - 04:51
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Thanks for the reply.

I did not realise that was the case. I'm told by BT that the line may be Full duplex and to try changing the setting and see what happens. If the link is indeed Full duplex should I see no more collisions?

rtjensen4 Thu, 07/30/2009 - 12:53
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Correct, once you switch to Full Duplex you shouldn't see any more collisions. Turns your one-lane road into a 2-lane highway.


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