Troubleshooting SFP transceivers and Packet captures

In an older blog post I was writing about Useful Cisco Commands for Troubleshooting cable problems. In this blog post I’m showing an additional, useful command for Fiber Optics troubleshooting and packet capturing on Cisco switches.

Cisco GLC-SX-MMD SFP transceiver
Cisco GLC-SX-MMDSFP transceiver

Show idprom interface

The command show idprom interface is showing the IDPROM (Identification Programmable Read-Only Memory) information of the installed SPF/SPF+ transceivers. I find this command useful to figure out the SFP/SFP+ Transceiver I am dealing with and if the SFP/SFP+ Transceiver was detected by a Cisco switch properly. Note: HEX output is truncated.

    #show idprom interface Gi2/0/26
    General SFP Information
    -----------------------------------------------
    Identifier            :   0x03
    Connector             :   0x07
    Transceiver           :   0x00 0x00 0x00 0x01 0x00 0x00 0x00 0x00
    Encoding              :   0x01
    BR_Nominal            :   0x0D
    Vendor Name           :   CISCO
    Vendor Part Number    :   FTLF8519P3BNL-CS
    Vendor Revision       :   0x41 0x20 0x20 0x20
    Vendor Serial Number  :   nnnnnnnnnnn
    -----------------------------------------------
    EEPROM PAGE A0 bytes
    -----------------------------------------------
    000:  HEXHEXHEX
    -----------------------------------------------
    EEPROM PAGE A2 Bytes
    -----------------------------------------------
    000:  HEXHEXHEX
    -----------------------------------------------
    Other Information
    -------------------------------------------------------
    Port asic num         : 04
    Port asic port num    : 02
    SFP presence index    : 01
    SFP iter cnt          : 83033469
    SFP failed oper flag  : 0x00000000
    IIC error cnt         : 0
    IIC error dsb cnt     : 0
    IIC max sts cnt       : 4
    Chk for link status   : 01
    Link status           : 01
    Autoneg enable        : 00
    Flow control Pause    : 00
    Flow control asymPause: 00
    Duplex mode           : 00
    PcsInfo               : 0x060D4E60
    MacInfo               : 0x060D4E40 0x060D4E48
    AutoNeg               : 0x060D4E48 0x060D4E50
    Sfp selection asic reg map
    --------------------------------
    stbi                 : 0x02
    sfpControl           : 0x5C
    Regs Loc             : 0xF0000000
    --------------------------------
    miscStatus
      rps300Stat1      0
      rps300Stat2      0
      rps300Present    0
      modeSwitchActive 0
    stackPhyControl
      sPhyLoopback     0
      sPhyALock1       1
      sPhyALock0       1
      sPhyBLock1       1
      sPhyBLock0       1
    stackCable
      cableIdA_1       0
      cableIdA_0       0
      eqSelectA_1      0
      eqSelectA_0      0
      cableIdB_1       0
      cableIdB_0       0
      eqSelectB_1      1
      eqSelectB_0      1
    SFF-8472 MSA EEPROM Data
    ===========================================
    000 :  HEXHEXHEX
    SFF-8472 Digital Diagnostic Monitoring Data
    ===========================================
    000 :  HEXHEXHEX
    YETI INTERNAL REGS
    -----------------------------------------------
    Location=0xD8000500     :  Value=0x00
    Location=0xD8000501     :  Value=0x00
    Location=0xD8000502     :  Value=0x00
    Location=0xD8000503     :  Value=0x00
    Location=0xD8000504     :  Value=0x00
    Location=0xD8000505     :  Value=0x00
    Location=0xD8000506     :  Value=0x00
    Location=0xD8000507     :  Value=0x02
    Location=0xD8000508     :  Value=0x00
    Location=0xD8000509     :  Value=0x40
    Location=0xD800050A     :  Value=0x00
    Location=0xD800050B     :  Value=0x00
    Location=0xD800050C     :  Value=0x05
    Location=0xD800050D     :  Value=0x00
    Location=0xD800050E     :  Value=0x01
    Location=0xD800050F     :  Value=0x00
    Location=0xD8000510     :  Value=0x0F
    yetiIICinited           :  Value=0x00000001
    yetiIICLockPassCnt      :  Value=0
    yetiIICLockFailCnt      :  Value=0
    yetiIICLockApp          :  Value=40
    -----------------------------------------------
Show idprom interface

Packet Capture

The famous packet capture commands on Cisco IOS is the monitor session command to activate the Switched Port Analyzer (SPAN). On my Cisco 3750 Switch series I would start a packet capture like in the example shown below and connect a laptop with Wireshark.

    #conf t
    (config)#monitor session 1 source interface Gi2/0/2
    (config)#monitor session 1 destination interface Gi2/0/10
Packet Capture on Cisco 3750: monitor session

On the Cisco 9200 and 9300 Switch series (IOSXE) the packet capture capability was expanded with monitor capture. To start a packet capture, an ACL (Access Control List) must be defined first. The capture session is then using the defined ACL. The packet capture in this example is running 30 minutes, after the capture I can transfer the packet capture file by SCP (Secure Copy) to my laptop for analysis with Wireshark.

    #monitor capture PCAP access-­list PCAP
    #monitor capture PCAP limit duration 1800
    #monitor capture PACP interface Tw1/0/14 both
    #monitor capture PCAP buffer circular size 10
    #monitor capture PCAP start
    ...running 30 minutes....
    #monitor capture PACP export scp://user:pass@ip:/capure.pcap
Packet Capture on Cisco 9200: monitor capture

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