Checking for noise on an optical line

Enter the show interface command and check the output for CRC errors or TX discards.

device# show interface eth 0/1 
Ethernet 0/1 is admin down, line protocol is down (admin down)
Hardware is Ethernet, address is 0000.aaaa.bbbb
    Current address is 0000.aaaa.bbbb
Pluggable media present
Interface index (ifindex) is 203431936 (0xc202000)
MTU 1548 bytes
10G Interface
LineSpeed Actual     : Nil
LineSpeed Configured : Auto, Duplex: Full
Priority Tag disable
Forward LACP PDU: Disable
Route Only: Disabled
Tag-type: 0x8100
Last clearing of show interface counters: 11:18:42
Queueing strategy: fifo
Receive Statistics:
    0 packets, 0 bytes
    Unicasts: 0, Multicasts: 0, Broadcasts: 0
    64-byte pkts: 0, Over 64-byte pkts: 0, Over 127-byte pkts: 0
    Over 255-byte pkts: 0, Over 511-byte pkts: 0, Over 1023-byte pkts: 0
    Over 1518-byte pkts(Jumbo): 0
    Runts: 0, Jabbers: 0, CRC: 0, Overruns: 0
    Errors: 0, Discards: 0
Transmit Statistics:
    0 packets, 0 bytes
    Unicasts: 0, Multicasts: 0, Broadcasts: 0
    Underruns: 0
    Errors: 0, Discards: 0
Rate info:
    Input 0.000000 Mbits/sec, 0 packets/sec, 0.00% of line-rate
    Output 0.000000 Mbits/sec, 0 packets/sec, 0.00% of line-rate
Route-Only Packets Dropped: 0
Time since last interface status change: 11:18:42

If errors are reported in the previous step, check the SFP transceiver and cable on the local switch and on the peer switch at the other end of the cable.
1. Enter the show media interface command on each device and check the Vendor Name field to check that the optics are Brocade- or Extreme-certified.
2. Try replacing the SFP transceiver.
3. Try replacing the cable.
If needed, enter the show media optical-monitoring interface ethernet command.