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Cisco SFP not connecting, shows signal, but with a fault

Cisco SFP not connecting, shows signal, but with a fault

Steve_Ballantyn
Contributor
Hello,

I have an Extreme X450-G2-48P-GE4 which I am linking to a Cisco 3750 series switch using two Cisco SFP 1000base SX modules (GLC-SX-MM). I am running ExtremeXOS version 16.1.2.14. I have no link lights, and no errors in my logs.

When I pull a debug on the port it shows signal is present, but that there is a "TX fault". I have tried increasing the debounce to 150 and then to 900, and rebooted the switch several times --- but still no connection.

Does anyone have any ideas on what I can try? I have two Extreme brand SFP's on the way, but I am trying to get this connection up in a hurry as users are anxious to get into new office space.
* X450G2-48p-G4.14 # debug hal show optic port 49
Port 49
SFP or SFP+: SFP
Signal: present
TX Fault: yes
SFP/SFP+ Vendor: CISCO-AVAGO
SFP/SFP+ Part Number: QFBR-5766LP
SFP/SFP+ Serial Number: AGS104255PX
SFP/SFP+ Manufacture Date: 061018
SFP/SFP+ Type: SFP/SFP+
Connector: LC
GE Compliance: 1000BASE-SX
Wavelength: 850
Also, I am *assuming* that the physical cable is good. But I had better be sure that it's not before I have the company come out to run a new line.

16 REPLIES 16

According to AVAGO specification SFP module asserts TX_Fault with "1A" hex data at the byte 65. This could happens due to next reasons:

TX_FAULT
A laser fault or a low VCC condition will activate the transmitter fault signal, TX_FAULT, and disable the laser. A low signal indicates normal laser operation and a high signal indicates a fault.

Eye Safety Circuit
Under normal operating conditions, the laser power will be maintained below the eye-safety limit. If the eye safety limit is exceeded at any time, a laser fault will occur and the TX_FAULT output will be activated.

So there is no restriction to use this module from switch side.
Try to use another SFP as this module could be deffective.

Here is the output from running the above command ...

X450G2-48p-G4.4 # debug hal show optic-info eeprom port 49
Port 49
SFP or SFP+: SFP
Signal: present
TX Fault: yes
SFP/SFP+ Vendor: CISCO-AVAGO
SFP/SFP+ Part Number: QFBR-5766LP
SFP/SFP+ Serial Number: AGS104255PX
SFP/SFP+ Manufacture Date: 061018
SFP/SFP+ Type: SFP/SFP+
Connector: LC
GE Compliance: 1000BASE-SX
Wavelength: 850

eeprom: Total Size 128, Values in Hex
00 01 02 03 04 05 06 07 08 09
-----------------------------------
000: 03 04 07 00 00 00 01 00 00 00
010: 00 01 0d 00 00 00 37 1b 00 00
020: 43 49 53 43 4f 2d 41 56 41 47
030: 4f 20 20 20 20 20 00 00 17 6a
040: 51 46 42 52 2d 35 37 36 36 4c
050: 50 20 20 20 20 20 20 20 20 20
060: 03 52 00 dd 00 1a 00 00 41 47
070: 53 31 30 34 32 35 35 50 58 20
080: 20 20 20 20 30 36 31 30 31 38
090: 20 20 00 00 00 de 00 00 06 e9
100: 3a 30 b9 bc 95 a3 20 f6 1a 07
110: bd 02 5a 44 7f 00 00 00 00 00
120: 00 00 00 00 21 30 5c 5a


Thanks for the hint. I am off site at the moment, and it takes a while to get up to where this switch is location. I am going to take a Raspberry Pi up there and put it on wireless, connected locally to the console port on the switch so I can do some remote troubleshooting. I will test this as soon as I can get it set up!

Stephane_Grosj1
Extreme Employee
It should work. What kind of fiber do you use?

Ooops, answered this above! Tripp Lite 25M Duplex Multimode Fiber 62.5/125 Patch Cable LC/LC 82ft.
GTM-P2G8KFN