Does patch-panels affect network speed?
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Posted by on June 29, 2008, 3:45 pm
Please log in for more thread options > lawrence.jones@siemens.com writes:
> >No, it won't ever fall back. The speed negotiation is done (at 10 Mbps)
> >based entirely on the capabilities of the devices at each end -- the > >quality of the connection between them doesn't enter into it at all. >
> Except when all the newbies come around with their home-made cables > with split pairs asking why their 100Mbps connections have failed to > negotiate at 100Mbps and only at 10Mbps because of the degraded signal? That doesn't happen. If both devices support 100 Mbps and can talk to each other at all, they'll negotiate 100 Mbps, no matter how dreadful the cable. The only way you get 10 Mbps is if at least one of the devices is manually forced to 10 Mbps or if the devices can't communicate at all (in which case 10 Mbps won't work, either). -- Larry Jones That's the problem with nature. Something's always stinging you or oozing mucus on you. -- Calvin | ||||
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Posted by Robert Redelmeier on June 29, 2008, 10:04 pm
Please log in for more thread options > That doesn't happen. If both devices support 100 Mbps and can talk
> to each other at all, they'll negotiate 100 Mbps, no matter how > dreadful the cable. The only way you get 10 Mbps is if at least > one of the devices is manually forced to 10 Mbps or if the devices > can't communicate at all (in which case 10 Mbps won't work, either). IOW, fallback from 100 to 10 is very unreliable/nonexistant. That matches my experience. -- Robert | ||||
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Posted by Mark Evans on June 30, 2008, 5:03 am
Please log in for more thread options > lawrence.jones@siemens.com wrote in part:
> > That doesn't happen. If both devices support 100 Mbps and can talk
> > to each other at all, they'll negotiate 100 Mbps, no matter how > > dreadful the cable. The only way you get 10 Mbps is if at least > > one of the devices is manually forced to 10 Mbps or if the devices > > can't communicate at all (in which case 10 Mbps won't work, either). > IOW, fallback from 100 to 10 is very unreliable/nonexistant.
> That matches my experience. IME "lights on, nobody's home" is the more common result. -- Mark Evans St. Peter's CofE Aided School Phone: +44 1392 204764 X241 Fax: +44 1392 204763 | ||||
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Posted by Robert Redelmeier on June 30, 2008, 9:38 am
Please log in for more thread options >> lawrence.jones@siemens.com wrote in part:
>> > That doesn't happen. If both devices support 100 Mbps and can talk
>> > to each other at all, they'll negotiate 100 Mbps, no matter how >> > dreadful the cable. The only way you get 10 Mbps is if at least >> > one of the devices is manually forced to 10 Mbps or if the devices >> > can't communicate at all (in which case 10 Mbps won't work, either). >
>> IOW, fallback from 100 to 10 is very unreliable/nonexistant.
>> That matches my experience. >
> IME "lights on, nobody's home" is the more common result. Agreed. Lights mean signal and activity. Not _clear_ signal and good frames, at least for 10/100 on most equipment. -- Robert >
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Posted by Doug McIntyre on June 30, 2008, 3:18 pm
Please log in for more thread options >lawrence.jones@siemens.com wrote in part:
>> That doesn't happen. If both devices support 100 Mbps and can talk
>> to each other at all, they'll negotiate 100 Mbps, no matter how >> dreadful the cable. The only way you get 10 Mbps is if at least >> one of the devices is manually forced to 10 Mbps or if the devices >> can't communicate at all (in which case 10 Mbps won't work, either). >IOW, fallback from 100 to 10 is very unreliable/nonexistant.
>That matches my experience. I've gone into a few situations where exactly that did happen. Split pairs, and the interface only links up at 10Mbps. Fix the split pairs, and it works at 100Mbps with no gear (or config) change. And there have been many posts over the years to this group with people coming here with that exact same problem. I'm not saying that it happens all the time, but it does happen from time to time. | ||||
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