Comcast Ethernet Feed

Derek Ivey derek at
Thu Mar 29 19:56:57 CDT 2012


We have a Comcast MetroE PtP connection between our office and our datacenter and I found that it was defaulting to half duplex. I forced both of my ends to 100 Full and it fixed my issue.


On Mar 29, 2012, at 8:47 PM, Brielle Bruns wrote:

> 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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