North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Problems connectivity GE on Foundry BigIron to Cisco 2950T
On Mon, 16 Jan 2006 00:24:35 +0000 (GMT Standard Time) Sam Stickland <[email protected]> wrote: > > On Mon, 16 Jan 2006, Mark Smith wrote: > > > On Sun, 15 Jan 2006 23:50:07 +0000 (GMT Standard Time) > > Sam Stickland <[email protected]> wrote: > > > >> > >> Hi, > > > > <snip> > > > >> > >> The cabling arrangement is: > >> > >> Foundry -- Straight -- Patch -- Underfloor -- Patch -- Crossover -- Cisco > >> GBIC Cable Panel Straight Panel Cable > >> > >> If I replace the final crossover cable with a straight, > > Just do that ^^^ and give it a try. > > Will do. > Having done a bit more looking into this myself, one thing that might be a cause is the cross-over, in the sense that if it is a 100BASE-T crossover, only two of the pairs will be crossed, and the other two pairs are usually wired straight. A GigE cross over, assuming you need one if you're ports don't support automatic cross over, has all four pairs crossed over (1-3,2-6,3-1,6-2,4-7,5-8,7-4,8-5). My guess would be that if a device only detects two of the four pairs crossed, it drops back to 100BASE-T. In other words, GigE cross overs are backwards compatible with 10/100BASE-T, but 10/100BASE-T crossovers aren't forward compatible with GigE. A GigE rated straight through path would be the first thing I'd test, after that, possibly try a GigE crossover somewhere between the devices. Regards, Mark. -- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
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