[c-nsp] Cheap 10G between 7600 and Procurve 5406zl

[Nick Hilliard]

On 17/03/2010 21:28, Lincoln Dale wrote:
> this assertion is also false.  i can categorically state that there
> has not been, there have been any number of quirks with "standards
> compliant" MSA transceivers.

To be fair, Lincoln, Marian is talking about a different level of 
incompatibility going on here.  There are quirks in all hardware 
interfaces (the free unix ethernet and SCSI drivers make interesting 
reading), but getting good compatibility between 10G chipsets and 
arbitrary SFP+ transceivers is going to be a whole lot more difficult 
than writing a driver to take into account that SFP+ model X does action 
Y in circumstance Z.  Analog to digital conversion is a black art.

> in either case the EDC issue to what i talked about is really only
> specific to LRM and Passive CX1 on SFP+. SR/LR are just fine.

I had been planning a small short-reach (800m) CWDM deployment using 
SFP+ optics.  What you say comes as rather bad news.

> what is used behind the scenes (XAUI, XFI) has no bearing on you as
> an end customer AFAIK - beyond whether something is available or
> not.

It's not particularly the transceiver MII which is the problem here, 
it's the form factor / end product.  XFP already delivers a good variety 
of optical interfaces, while X2 doesn't really come close in terms of 
range or suppliers.  This means that if you need an exotic X2, both 
purchase and support/replacement lead times are going to be bad.  This 
isn't a huge problem if you're a large customer buying lots of kit, but 
if you're a small customer, it's incredibly expensive to ask your local 
Cisco partner to keep 10 different types of DWDM X2s in stock as spares.

Also, the price won't be as good, because there are fewer manufacturers 
producing fewer varieties.

In addition, by buying kit which takes X2 modules, you're committing a 
huge amount of transceiver capex on a particular vendor (i.e. Cisco or 
HP) which cannot then be moved to another vendor, because no-one else in 
the industry uses them.  This is strong vendor lock-on.

Nick