Cisco Catalyst IOS Blocks Compatible Transceivers

My Cisco switch disables the port when I install a compatible transceiver module. Help!?

Cisco Compatible SFP Transceiver
GLC-SX-MM
Cisco Compatible SFP Transceiver

Cisco has dominated the IP/Ethernet switching and routing market since its very beginnings. While Cisco has continued to innovate with many exciting and useful features, they have also taken advantage of their dominant position with various ‘strong arm’ tactics, creating barriers to competitors to beef up profits. A perfect example is their tactic of attempting to discriminate between ‘Cisco original’ and ‘Non-Cisco’ optical transceivers. The idea is that if customers are forced to equip their Cisco brand switches only with Cisco brand optical transceivers, then Cisco can charge almost any price they want for those transceivers.

Back in 2003, Cisco slipped a new little feature into a routine Internet Operating System (IOS) update on their Catalyst line of switches: rejection of optical modules that were not deemed ‘Cisco brand’. With this ‘feature’, when a non-Cisco transceiver was installed in a Cisco Catalyst port, an “errdisable cause gbic-invalid” error is generated and the port is disabled. The participants in the development of the Multi-Source Agreement (MSA), the defining standards of various pluggable optical transceivers, would probably find this tactic especially ironic. Cisco was among the system vendors most strongly encouraging the largest optical transceiver component vendors in the world to work on these standards… only to undermine the standard by only allowing Cisco brand components to function in their systems!

So… am I really stuck paying exorbitant prices for optics?

The good news is, within a few years of Cisco’s restriction against non-Cisco transceivers two things happened to allow customers to take advantage of competitively priced, standards compliant optical transceivers. First, many of Cisco’s largest customers argued loudly, and often, that they would switch to other vendors if they were not allowed to ‘plug-and-play’ standards compliant transceivers between their Cisco and non-Cisco gear. Second, many non-Cisco suppliers figured out what the IOS was looking for and simply made their optical transceivers look indistinguishable from Cisco original ones. When Cisco equipment operators plug these ‘fully Cisco-compatible’ optical transceivers in their switch they just come up and run with no error messages, so…problem solved!

In response to the hue and cry raised by their largest customers, Cisco add a couple of new CLI commands (IOS versions 12.2(25) or later). These commands override the ‘feature’ restricting use to Cisco brand optical modules. The following are these two commands:

  • service unsupported-transceiver: Upon entering this command, the switch will generate a warning message but, subsequently the system should allow non-Cisco transceivers to function properly. When a port goes into the ‘errdisable’ state, it typically takes five minutes (300 seconds default) to clear. To be absolutely certain this does not occur, the following command should be entered.
  • no errdisable detect cause gbic-invalid: This command instructs the switch specifically to ignore any ‘gbic-invalid’ condition that should occur. No error or warning message is generated; so the operator should be good to go with any standards compliant optical transceiver, regardless of vendor.

 The bottom line…

Though Cisco has attempted to force their customers to buy a fully standardized part at hugely inflated prices, market forces have won out. So network operators have two choices when dealing with Cisco IOS attempts to block 3rd party optical transceivers. One option is to enter two special commands on each Catalyst switch to disable the ‘feature’. The second, our recommendation, is to simply purchase fully-Cisco-compatible optical transceivers from one of several reputable 3rd party sources.

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