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Occasional Contributor
Posts: 9
Registered: ‎02-10-2008

ISL CRC Errors_ what is an acceptable threshold

One of the ISL cables we have laid seems to displaying CRC errors. We have since relaid it and the errors have reduced but not gone away. I've sent some data through this link and pasted the ports in question below (ouput is from porterrshow).


        frames  enc  crc  too  too  bad  enc disc link loss loss frjt fbsy
       tx   rx   in  err shrt long  eof  out   c3 fail sync  sig
     =====================================================================
  4:  617m 2.8g   0    2    0    0    0  268k   0    0    2    9    0    0   << switch_one
  4:  2.8g 617m   0   29    0    0    0    1  333    0    1    5    0    0   << switch_two


I'm trying to find advice & documentation which might tell me:
- what threshold of CRC errors is acceptable on an ISL link.

There are some possibilities:
- error is caused by dirty/faulty SFP
- new cable laid is also faulty

- firmware incompatibilities between host-hba, array-hba and SFP  (I'm discounting this as Firmwares are consistent and other ISL links are unaffected).

I plan to swing the new cable to a vacant set of SFPs on either ends of the ISL. I am however concerned whether this will 'transfer dirt' from one sfp to another via the cable's surface during the switch. I have very little experience of this .. any suggestions?

I'd love some pointers but I'd appreciate is pointers to some documentation for a little RTFM (my google batting average is low recently).


Any thoughts? (Thanks in advance)

Frequent Contributor
Posts: 140
Registered: ‎02-27-2008

Re: ISL CRC Errors_ what is an acceptable threshold

HI in_the_corner

How long are your ISL cables ? are you running single mode fiber or mulitmode fiber ? Which kind of SFP's are you using.

I setup a cross campus fiber channel fabric last year , which was using single mode fiber , which was about 1km (give or take going through all the distrubtions points around campus)

What type of SFP's are you using ? , I had to get special SFP's from Sun in order to get our link up at running. What version of Fabric OS are you running on your switches

Cheers

David

Occasional Contributor
Posts: 9
Registered: ‎02-10-2008

Re: ISL CRC Errors_ what is an acceptable threshold

I'm using:


single-mode fibre

Sun-branded SFPs

FABOS 5.2.0a

It's been suggested I check out www.t10.org and also google for SNIA on the off-chance there is something there. Again, if anyone suggests any pointer, or hints or even 'musings', they'd be all welcome.

External Moderator
Posts: 4,811
Registered: ‎02-23-2004

Re: ISL CRC Errors_ what is an acceptable threshold

in the corner
the answer is very simple the correct acceptable treshold is NO crc error
CRC Error are fatal error witch other word if you get a crc error is this most caused by defective components or wrong or missing config parameter
another reason can be also errors on the SWITCH Port i would reset the port and delete all port log

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