[c-nsp] SFP & GBIC module compatibility

[Mikael Abrahamsson]

On Wed, 20 Dec 2006, Pak Tong Poy wrote:

> From my understandings, SFP or GBIC are of open standard. And the standard
> modules should work with any router. Is it a marketing ploy that some
> vendors (say Cisco reseller) say that we must buy the modules from them in
> order have 100% compatibility?

Yes and no. Generally GBICs have been open so you can use any brand. If 
you run into trouble, the vendor of the equipment won't support you. With 
SFPs it changed in that some manufacturers (mainly Cisco and Extreme 
Networks afaik) started to make their software check so that any SFP 
inserted into the equipment required to have a certain string/code in its 
NVRAM, otherwise the software wouldn't activate the port.

It's widely known that interoperability is not as easy as it might sound, 
and vendors have been hit by it. That's one reason why they want you to 
buy their optics instead of buying it from someone else, because they will 
have tested it ahead of time, so you don't have to.

Now, there is another reason also for them to do it, and that's economics. 
The businesscase selling branded optics for 1GE for instance, is simply 
excellent. You rebrand something and upcharge 3-5x, you get less support 
calls, and the only thing you have to do is test it ahead of time and make 
the OEM keep their promises. For 10GE (XFP and Xenpaks) margins have gone 
down considerably, hopefully this will remain in the future. I prefer to 
buy vendor tested optics, but the price difference needs to be reasonable.

Of course customers have realised this and cried bloody murder, so 
eventually first Extreme Networks and then Cisco started shipping software 
that did remove the optics checks, or at least introduced a command to 
disable the check. This is an operational nightmare as you have to keep 
track of which software the unit is shipped with and if it has this check, 
and you have to educate the installer to configure the unit properly. You 
also might run into what others have mentioned, namely SFPs stop working 
after software upgrade because you intalled a software that had SFP 
checks.

There are two main advantages to being able to interchange optics between 
vendors. Price and spare parting. Keeping Cisco SFP LX and Extreme 
Networks SFP LX spareparted, when both might be from Finisar, is just bad 
economics. You want to spare part just "SFP LX" and don't have to care 
about brand.

So don't forget to include the requirement to use "any SFP" next time you 
do RFQ. Only market pressure can influence vendors to stop locking us into 
their own pluggable optics.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se