Showing posts from February, 2012

Cisco Configuration Tip - 3rd Party SFP Modules

It is possible to use non-Cisco SPF modules in a Cisco Catalyst switch. By default this is forbidden not allowed, but a top secret hidden command can make this happen.

switch(config)#service unsupported-transceiver
switch(config)#no errdisable detect cause gbic-invalid

In the SFP modules EEPROM, a Serial Number, Vendor Name & ID, Security code and a CRC. The switch reads these values and if they are not "Cisco" values reports an error such as:

%PHY-4-UNSUPPORTED_TRANSCEIVER: Unsupported transceiver found in Gi1/0/1
%GBIC_SECURITY_CRYPT-4-VN_DATA_CRC_ERROR: GBIC in port 65538 has bad crc

The official position from Cisco is:
Q. Do the Cisco Catalyst 3750 Series Switches interoperate with SFPs from other vendors?
A. Yes, starting from 12.2(25)SE release, the user has the option via CLI to turn on the support for 3rd party SFPs. However, the Cisco TAC will not support such 3rd party SFPs. In the event of any link error involving such 3rd party SFPs the customer will have to …