SUMMARY: fta0: MAC CRC Error

From: <marty.cruchten_at_paulwurth.com>
Date: Fri, 31 Jul 1998 10:07:49 +0200

Hi managers,

Many thanks to Kevin Reardon and Chan George who sent me their
experience with this error message. Basically, it seems that this error
message isn't too severe and that the cause is mainly nertwork hardware
like HUB's, repeaters, routers. I will post the answer of Kevin Reardon
at the end of the original message. He gives very valuable information
and hints to analyze the problem.

==================================================
ORIGINAL MESSAGE
>From last saturday on, I have some problems with the fddi network. On
saturday, it started with our 2 servers (2100) (server1 and server2)
which are in a Digital ASE cluster. One server couldn't see the other
one any more. I could't do a ping from one server to another. On
server1, I still could do a ping to other servers but on server2, ping
answered with the message:
            ping: sendto: No buffer space available.
I rebooted server2 and everything went fine again.

On Thursday morning, during the backup of server1 to server3 (where the
tape is connected to), I got the message:
    fta0: MAC CRC Error: DA: ... => SA: ...
where DA represents the hardware address of the FDDI interface of
server1 and SA that of the FDDI interface of server3.

Today, I received on my 4 Unix servers (at the same time) the SAME
following error message:
    fta0: MAC CRC Error: DA: ff-ff-ff-ff-ff-ff => SA: 00-60-97-46-b6-5c

I have the impression that something with the network is going wrong.
Until now, we newer had this error messages.

- Could you give me any hints on this problem how I could detect the
problem source?
- Is there a way to track the HW-address 00-60-97-46-b6-5c because I
don't know to who this address belongs to?
- Is there anyone who experienced similar problems?
- I suppose it is a HW problem but could this problem also be a SW
problem?

==================================================
ANSWER OF KEVIN REARDON

Sorry, I don't know what is causing your network problems, but I have
seen
a lot of MAC CRC errors on our FDDI network without any serious
consequences. MAC stands for "Media Access Control", while DA and SA
mean
destination and sending address, respectively. Basically, I think it
involves some sort of collision on the FDDI ring and several DEC
technicians have assured me that it isn't any problem. I have had about
3000 of these messages in the past year on our network of ~200 machines
and
they seem to come preferentially from certain machines.

For associating ethernet addresses with actual IP addresses, I use
arpwatch, available from:
ftp://ftp.ee.lbl.gov/arpwatch.tar.Z
that maintains a databases of the arp addresses on the networks. It
works
fine. I also found that by telneting to our DEC router, one can also
examine the router's list of ethernet to IP addresses.

To see the details on the errors and statistics of your FDDI interface,
you
can use the command:
netstat -I fta0 -s
These statistics, which are more fully explained in Digital's "Network
Administration and Problem Solving" manual, might indicate the source of
the errors.

I hope this helps.

kevin reardon
Osservatorio Astronomico di Capodimonte

==================================================
Marty Cruchten
system manager - SAP technical consultant
Paul Wurth S.A.
Luxemburg
marty.cruchten_at_paulwurth.com
Received on Fri Jul 31 1998 - 08:09:20 NZST

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