Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

CISCO MDS switch port unavailable

Hi there,

I have a backup project i am carrying out for our customer. we have had an issue with Cisco MDS FC switch zoned with a tape library and SAN storage.

Every time i run a backup to tape, the FC ports on the tape drive go offline, the FC ports on the switch go offline as well. When i change the cabling on the Cisco switch,the ports on the drive work for a while and then goes offline again.

Please advice if there are any performance configurations to run in the cisco switch since i am backing up TBs of data?


Your help will be appreciated.




VIP Green

What is the status of the

What is the status of the port in the down state ?

error disable ?

post show port counters

will the port come up again, or do you disable / enable port ?

New Member

hi wdey,the ports are showing

hi wdey,

the ports are showing errDisable, i have disabled and enabled ports and the backup is running..

how do i resolve this permanently?





VIP Green

see eg.

see eg.

Do you see a console / syslog message which should indicate the cause of the errdisable ?

I guess this must be a physical link issue: cable, port, transceiver; do you see crc error counter going up ?


New Member

Hi wdey,this is the port

Hi wdey,

this is the port status when it goes offline:

SW01# sh int fc1/27
fc1/27 is down (Error disabled - bit error rate too high)
    Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
    Port WWN is 20:1b:54:7f:ee:e2:8d:00
    Admin port mode is auto, trunk mode is on
    snmp link state traps are enabled
    Port vsan is 2
    Receive data field Size is 2112
    Beacon is turned off
    5 minutes input rate 0 bits/sec, 0 bytes/sec, 0 frames/sec
    5 minutes output rate 0 bits/sec, 0 bytes/sec, 0 frames/sec
      263045 frames input, 12907156 bytes
        0 discards, 0 errors
        0 CRC,  0 unknown class
        0 too long, 0 too short
      4308477 frames output, 8677425352 bytes
        1 discards, 0 errors
      2 input OLS, 2 LRR, 0 NOS, 3 loop inits
      5 output OLS, 2 LRR, 1 NOS, 3 loop inits
    Interface last changed at Mon Oct 13 07:36:46 2014


There is this link:

I referred to the customer to this link on disabling, bit-rate error threshold but the customer is concerned about any disruption on Production Storage (there is a redundant MDS with redundant connectivity to production storage).

does disabling bit-rate affect performance/availability of the switch?



VIP Green

I would investigate what the

I would investigate what the real problem is; disabling bit-error threshold is bad; in the end, you will have to retransmit the broken FC frames, which will severly impact the performance.

Is this port actually a F-Port ?

switch# show interface 

fc1/1 is up

    Hardware is Fibre Channel, SFP is short wave laser

    Port WWN is 20:0b:00:05:30:00:8d:de

    Admin port mode is F

    Port mode is F, FCID is 0x610000

    Port vsan is 2
CreatePlease login to create content