2950T's Gigabit CRC errors.

[richardjad]

Ok, I have several 2950T's. (Version 12.1(22)EA5)

When I try and connect two of them together using their gigabit ports with a CAT6 crossover cable (all four pairs crossed, tested with gigabit fluke) I get CRC and input errors that causes severe bandwidth problems.

If I use their 100Mb ports, or tie the Gb ports down to 100Mb, it works fine.

I can't believe that the 4 or so 2950's I've tried this on all have faults. (Especially since they were bought over a period of months from different suppliers - i.e. batch roblems seems unlikely)

I've tried reverting to factory config with no difference. (write erase, reload)

Any useful suggestions would be appreciated.

[amit-singh]

Richard,

I believe its just a cabling issue. Try to get some branded cables for you. Its just the physical layer issues with the CRC and input errors.

Did you try setting the ports to 1000 MBPS on both the sides. You have 2950T with 2 10/100/1000 ports.

Its just a physical layer issue, try some different cable a branded one.

regards,

-amit singh

[richardjad]

The unbranded crossover cables I used passed all the CAT6 noise tests etc. on our Gb test gear.

However, I'm willing to use branded cables. Does anyone have any recommendations on a specific brand / cable?

I'll also try specifically setting the ports to 1Gb (rather than auto) on both sides and get back to you. (I think I already tried this though).

[richardjad]

double post.