Reception problem with frames coming from a 3560-E

Unanswered Question
Dec 3rd, 2007
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Hi,


I'm transmitting frames between 2 electronic board via a 3560-E switch. Each board is made with FPGA and broadcom ethernet chip. Frames are raw ethernet. I observed transmission problems for switch to board communication. I did some experiences:


Board 1 => 3560-E => board 2 : OK at 100 M

Board 1 => 3560-E => board 2 : Problem at 1Gb

Board 1 => Netgear switch => board 2 : OK at 1Gb

Board 1 => 3560-E => Netgear switch => board 2 : OK at 1Gb


Board 1 and board 2 are the same. Netgear switch is not configurable. Problems appears for transmission from switch to board at 1 Gb. The only signals I can access on my board are an error bit, an enable bit and a data bus coming from broadcom chip and going to FPGA. About 50% of frames are gave with an error by broadcom chip at 1Gb (output chip frames are gave with error bit set to 1 and 1 preamble byte is missing in data frames). This problem disappears when I put a netgear switch between my board and the switch (So transmission from board to switch is working at 1Gb). Broadcom board is set to autonegociation and it seems there is no problem.

The switch doesn't give errors. Autonegociation is going well. There are no other ethernet links connected to switch. Results are the same using the switch with no configuration or configurating ports (assigning static mac addresses, disabling spanning tree, disabling keepalive, disabling CDP). I did it with autonegociation and forcing switch to 1Gb.

I observed same errors with a 2960-G instead of 3560-E.


Do you know what could be the problem ? Could it be because of physical interface problems ?



Thanks


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