[c-nsp] Cisco and third party transceivers

[Nick Hilliard]

On 30/09/2011 00:39, Martin T wrote:
> ..but manufactured in Asia. On the other hand, there are manufacturers
> like Finisar, Prolabs, Agilent etc, which make decent transceivers as
> much as I have experience. In addition, according to this article:
> http://www.lightreading.com/document.asp?doc_id=102950 ..Cisco buys
> SFP directly from Finisar. Do you see a difference in "Cisco branded
> Finisar SFP" and "Finisar SFP" other than content of EEPROM?

Cisco buys transceivers from several companies.  Sometimes the same product
SKU from a particular vendor might actually be sourced from several
different transceiver manufacturers.  Do you think for a moment that that a
GLC-LH-SM bought in 1999 is going to be exactly the same component as a
GLC-LH-SM bought in 2011?  Of course it isn't.

Transceiver compatibility is a really difficult area.  And one transceiver
is not the same as another.  Bugs slip into the transceiver firmware and
hardware.  Some vendors produce complete trash.  Some vendors produce
really high quality products (e.g. finisar, opnext, etc)

> It's a third-party SFP directly from China. As much as I understand,
> it doesn't have any sort of Cisco-branding, does it? Regardless it
> supports DDM.

DDM is defined in SFF8472.  It's nothing particularly to do with Cisco.

> In addition, in the past, has there been times where one really was
> forced to use transceivers with Cisco serials because there were no
> "service unsupported-transceiver" and "no errdisable detect cause
> gbic-invalid" commands? Maybe some seasoned network engineer
> remembers..

Yes, that was the case in the past.  And unfortunately, Cisco have recently
either deliberately started ignoring "service unsupported-transceiver" on
some of their new products, or else the transceiver device drivers are
sufficiently portably written that they no longer work with many types of
transceiver.  Either way, transceiver compatibility problems are rearing
their ugly head again in a major way.

Nick