[c-nsp] Will UDLD work with converters ?

[Justin Shore]

Jeff Fitzwater wrote:
> Is there any issues with running UDLD with TX to Fiber converters at 
> each end of a gig cisco to cisco link?   We are just over the distance 
> budget with the 10KM optics.
> 
> 6500 TX port--- to fiber converter--- 18KM fiber--- to converter--- back 
> to TX port on 3750.

Should work fine.  I'm doing the same thing over several back to back 
media converters with 80k optics.  I'd love to replace the MCs with 
something better but otherwise UDLD works fine over them.

> We are looking at the converters because the Cisco ZX optics are very 
> expensive and the converters with 30KM optics are much cheaper than the 
> 60 KM ZX optics.

Agreed.  This is on my list of major Cisco gripes.  10km is laughable in 
the SP world.  Where are the 20k and 40k optics?  Where are the 80k and 
110k optics?  Cabletron had 110k optics a decade ago.

The single-strand Cisco GigE optic is limited to 10km too. 
Single-strand optics are critical in the SP world.  Not everyone has 
excess bundles of dark fiber to play with to turn up a simple GigE link. 
  I understand that Cisco wouldn't sell a lot of these since most of 
their business is enterprise.  I get that.  I would suggest that they 
pick a well-known and reliable SFP manufacturer like Champion and 
support their optics.  Fill in the void with someone else's gear if you 
don't think the cost would justify the benefits of doing it yourself. 
There are other ways to do things besides doing it all in-house.

Another major Cisco SFP gripe I have is that some BUs require optics 
that no other BU supports which makes common sparing across your product 
lines impossible.  The ONSs require specific optics.  The GLC- and SFP- 
that the switches and routers support don't work in ONS's LCs like the 
XPonder.  We've found that the SFP- optics aren't supported in some 
switches with older code.  DOM isn't universally supported so why pay 
for thee DOM optic when your switch or linecard doesn't support it. 
DWDM SFP support was added to some switches in the later 12.2(40+)SE 
releases such as 12.2(46)SE for the ME3750.  However it wasn't added to 
all switches such as the 3560, 3750, or 2960 but it was added to the 
3560/3750 E series.  The beefy 4948s and monster 4900Ms are still out in 
the cold on DWDM support for SFPs too (I know that the 10G X2 optic 
supports DWDM).

It seems to me that there should be a standards body within Cisco that 
should mandate certain minimum requirements of all product lines.  If 
and when there is the ability for BUs and product lines to share common 
and trivial products like SFPs then they should require it.  It would 
save them R&D and QA money if nothing else.

Back to your question though, yes UDLD should work fine over MCs.

Justin