Comcast Ethernet Feed

Brielle Bruns bruns at
Thu Mar 29 19:47:11 CDT 2012

On 3/29/12 6:36 PM, Brian R. Watters wrote:
> We are about to accept a 20MEG Ethernet feed via Comcast and their
> fiber plant as well as a BGP feed across the same link.
> I have a space GIGE interface on a 7206VXR and would like to know
> best practice for deploying for optimal performance across this
> interface.
> Any ideas and or direction would be extremely helpful as we are
> seeing some real issues such as.
> Direct connect (without BGP) to the CPE from Comcast (Fiber to
> Ethernet) via a laptop gives the level of performance we would
> expect, However as soon as we terminate to our router via the GIGE
> which is set to 100MB full duplex and all flow control turned off
> (Negotiation auto) per Comcast and connect up via a 100MB fast
> Ethernet interface directly connected we get a fraction of the speed
> when direct connected.

 From my own experience here with our 7200s, some of the PA based 
100BaseT interfaces (ie: not on the IO module) can not negotiate 
100-full, but rather only half.  This leaves one end diff then the other 
and creates issues with performance.  Try forcing both the laptop and 
router to 100-full and see if it helps.

Brielle Bruns
The Summit Open Source Development Group    /

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