[j-nsp] GigE: M10 <-> Cisco Catalyst 6509: oversized and corrupted frames

Matti Saarinen mjs at cc.tut.fi
Fri Mar 28 08:14:40 EST 2003

Josef Buchsteiner <josefb at juniper.net> writes:

>> Both ends complain about the packets they are seeing. On M10, the
>> number in oversized frames counter increases.
> this might be normal if you use tagged interface connections
> and the frame is longer then 1518 including FCS. Although all
> works perfect the counter is increasing as oversizd frames.

     Thanks, now I'm able to iterpret the counters a little bit
     better. I do indeed use tagged frames.

>>  The 6509 complains about corrupted IP packets, too.
> so you get checksum error when you ping the interface address
> of the cisco ?  is this consistent ?

     No, I don't get any errors and the errors do show up a few times
     in a day. The interval between the errors isn't contant.

     I attached an analyser to a another GigE port on Cisco and
     configured the switch to copy all the traffic it receives from
     M10 to that port. The analyser has now been scanning the packets
     for a three days and it has seen no errors. I could be that the
     Cisco doesn't mirror packet containing errors.

     Still, I think that there's nothing wrong in a way Juniper sends
     the packets. The errors must be caused by some other equipment.


- Matti -

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