How to test SFP module in Cisco
Cisco brand switches are most widely used networking devices in the world. They are key building blocks for any network, and they connect multiple devices, such as computers, wireless access points, printers, and servers on the same network within building or campus.
Cisco switches utilize different form-factor transceivers which helps to achieve many different functions and usage scenarios. The most common transceivers are SFP+, XFP, QSFP+, QSFP28 and CFP2. Nevertheless, Cisco offers also copper transceivers, which allows to transform the SFP+ port to RJ45 (CAT5, 6) cable compatible port – 10G or 1G data rate, depending on required configuration and hardware setup.
Important factor is to make sure that Cisco compatible transceivers are fully compatible with your Cisco switch. This can be done through transceiver testing steps. Steps described here will be based on CISCO NX-OS.
First step would be to know your switch or router and what kind of transceivers it actually supports. To find out your switch model number and software version used, you can issue the show version command in the command-line interface (CLI).
switch# show version
Cisco Nexus Operating System (NX-OS) Software
Software
BIOS: version 07.59
NXOS: version 10.2(6)
BIOS compile time: 08/26/2016
NXOS image file is: bootflash:///nxos64-cs.10.2.6.M.bin
NXOS compile time: 8/31/2023 12:00:00 [08/29/2023 21:07:36]
Hardware
cisco Nexus9000 C93180YC-EX chassis
Intel(R) Xeon(R) CPU @ 1.80GHz with 24617872 kB of memory.
Processor Board ID FDOXX..
Device name: switch
bootflash: 53298520 kB
Kernel uptime is 0 day(s), 0 hour(s), 30 minute(s), 10 second(s)
Second step is to identify which transceiver module part numbers does your Cisco switch support. This can be done by searching the Cisco switch hardware model in the Cisco Optics-to-Device Compatibility Matrix website. Search results should display all the possible cisco transceiver part numbers and they respective requirements for switch software version.
Third step after module part number identification is to test the exact transceiver module in the switch. Module identification can have two different states – transceiver is accepted and hardware type changes accordingly to transceiver data rate, or on the other hand – states that transceiver is not supported. This information can be obtained at the first moments after plugging in the transceiver in the switch. You only need to issue the log command – show logging.
Successful transceiver identification:
2024 Jun 5 10:13:22 switch %ETHPORT-5-IF_HARDWARE: Interface Ethernet1/49, hard
ware type changed to 25G
Unsuccessful transceiver identification:
2024 Jun 5 10:13:31 switch %ETHPORT-3-IF_UNSUPPORTED_TRANSCEIVER: Transceiver o
n interface Ethernet1/31 is not supported
If the third step is successful then it is possible to continue to the fourth step. Fourth step is to check if transceiver has basic recognition information, as its Vendor name, Serial number, and other basic data. This kind of information can be observed after executing the show interface ethernet slot/port transceiver command. Practically this can be done like this in the switch CLI:
switch# show interface ethernet 1/17 transceiver
Ethernet1/17
transceiver is present
type is GLC-BX40-D-I
name is CISCO-EDGE
part number is BIDI1GSFP41BDSCI
revision is A
serial number is EO12408230007
nominal bitrate is 1300 MBit/sec
Link length supported for 9/125um fiber is 40 km
cisco id is 3
cisco extended id number is 4
cisco part number is 10-2940-01
cisco product id is GLC-BX40-D-I
cisco version id is V01
Additional step for this command is to include detail keyword. Then switch output offers also digital diagnostics monitor – DDM (DOM) information.
switch# show interface ethernet 1/17 transceiver details
Ethernet1/17
transceiver is present
type is GLC-BX40-D-I
name is CISCO-EDGE
part number is BIDI1GSFP41BDSCI
revision is A
serial number is EO12408230007
nominal bitrate is 1300 MBit/sec
Link length supported for 9/125um fiber is 40 km
cisco id is 3
cisco extended id number is 4
cisco part number is 10-2940-01
cisco product id is GLC-BX40-D-I
cisco version id is V01
SFP Detail Diagnostics Information (internal calibration)
----------------------------------------------------------------------------
Current Alarms Warnings
Measurement High Low High Low
----------------------------------------------------------------------------
Temperature 34.41 C 90.00 C -45.00 C 85.00 C -40.00 C
Voltage 3.22 V 3.80 V 2.70 V 3.70 V 2.80 V
Current 9.89 mA 100.00 mA 0.00 mA 90.00 mA 0.10 mA
Tx Power -1.29 dBm 0.99 dBm -6.00 dBm 0.00 dBm -5.00 dBm
Rx Power -9.26 dBm 0.99 dBm -26.98 dBm 0.00 dBm -25.22 dBm
Transmit Fault Count = 0
----------------------------------------------------------------------------
Note: ++ high-alarm; + high-warning; -- low-alarm; - low-warning
The DDM information is represented in this output only if non-copper transceiver is used.
Transceiver detail command offers to us various benefits. One of them is a quick diagnosis if transceiver is not broken and can respond to switch requests. Otherwise DDM information allows us to determine the incoming signal strength (Rx Power) which also indicates very approximate link attenuation.
Fifth step in transceiver testing with Cisco equipment would be to check link status and statistics.
switch# show interface ethernet 1/9 status
--------------------------------------------------------------------------------
Port Name Status Vlan Duplex Speed Type
--------------------------------------------------------------------------------
Eth1/13 -- connected routed full 10G 10Gbase-SR
switch# show interface ethernet 1/13
Ethernet1/9 is up
admin state is up, Dedicated Interface
Hardware: 100/1000/10000/25000 Ethernet, address: 0027.e380.11f7 (bia 0027.e38
0.1200)
MTU 1500 bytes, BW 10000000 Kbit , DLY 10 usec
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, medium is broadcast
full-duplex, 10 Gb/s, media type is 10G
Beacon is turned off
Auto-Negotiation is turned on FEC mode is Auto
Input flow-control is off, output flow-control is off
Auto-mdix is turned off
Rate mode is dedicated
Switchport monitor is off
EtherType is 0x8100
EEE (efficient-ethernet) : n/a
admin fec state is auto, oper fec state is off
Last link flapped 00:00:29
Last clearing of "show interface" counters never
1 interface resets
Load-Interval #1: 30 seconds
30 seconds input rate 88 bits/sec, 0 packets/sec
30 seconds output rate 152 bits/sec, 0 packets/sec
input rate 88 bps, 0 pps; output rate 152 bps, 0 pps
Load-Interval #2: 5 minute (300 seconds)
300 seconds input rate 16 bits/sec, 0 packets/sec
300 seconds output rate 16 bits/sec, 0 packets/sec
input rate 16 bps, 0 pps; output rate 16 bps, 0 pps
RX
0 unicast packets 3 multicast packets 0 broadcast packets
3 input packets 777 bytes
0 jumbo packets 0 storm suppression bytes
0 runts 0 giants 0 CRC 0 no buffer
0 input error 0 short frame 0 overrun 0 underrun 0 ignored
0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop
0 input with dribble 0 input discard
0 Rx pause
0 Stomped CRC
TX
0 unicast packets 3 multicast packets 0 broadcast packets
3 output packets 774 bytes
0 jumbo packets
0 output error 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble 0 output discard
0 Tx pause
In conclusion testing transceiver in a Cisco switch requires some basic CLI command knowledge, and information from Cisco equipment compatibility matrix. It is essential to acknowledge current Cisco switch hardware and software version because this information is required to successfully identify which transceiver is supported on the platform and which is not. The further testing steps can be easily executed by junior network engineer, or by professional.
The last two commands display information whether port is connected, not connected or error disabled and offers us with information about port statistics, – if the link is error free. For example, CRC errors might indicate that patch-cord is not clean.
