Dmitry Tkachenko
Guest
|
 Posted:
Wed Sep 15, 2004 9:50 pm Post subject:
Re: Baystack 470 with 1000Base-SX GBIC |
|
|
| Quote: | You might want to check the release notes.
To avoid any problems,I use Nortel SX Gbics.
I check release notes and not see any remarks abount non NN GBIC's, i |
see only list supported NN GBIC. IMHO standаrt LX or SX NN GBIC
will be work on other swithes, like 3Com, may be this reasoning is
wrong? |
|
Walter Roberson
Guest
|
| Posted:
Wed Sep 15, 2004 11:37 pm Post subject:
Re: Baystack 470 with 1000Base-SX GBIC |
|
|
In article <bc93098e.0409150950.5bd96258@posting.google.com>,
Dmitry Tkachenko <tdn2@mail.ru> wrote:
: I check release notes and not see any remarks abount non NN GBIC's, i
:see only list supported NN GBIC. IMHO standаrt LX or SX NN GBIC
:will be work on other swithes, like 3Com, may be this reasoning is
:wrong?
Unfortunately, GBICs are not standardized quite enough that one can be
sure that any particular vendor's GBICs will work with any other
vendor's equipment.
Some vendor's equipment looks at the manufacturer and serial number
information on the GBIC, and will refuse to allow unapproved GBICs. I
have not run into this situation myself, but I have read about it.
Some vendors make strong statements that you should only use their
GBICs, or should only use approved GBICs. However, Nortel and Cisco do
not make their own GBICs: they buy them from OEM manufacturers. It is
common for those manufacturers to make generic GBICs to the -same-
technical specifications as the "official" GBICs, just putting a
different label on them (and perhaps putting a different internal
identification string.) This means that there are some very high
quality GBICs on the market for a fraction of what Nortel or Cisco
charge, that will work just as well as Nortel's or Cisco's.
There are other manufacturers (or other production lines at the same
manufacturers) that make GBICs to lower standards, using cheaper
components or not doing as much quality control. Those GBICs can be
very inexpensive. In some situations, the really cheap GBICs will work
quite well -- especially if the distances are relatively short and you
are not using shoddy fibre. However, the very cheap GBICs are sometimes
tempermental: they might work in one slot but not in the next slot over
in the same device. And I would not want to count on a very inexpensive
GBIC for long distance work where you do not have a lot of loss margin
available.
Sometimes, even expensive fully-branded GBICs "go flakey" and you start
getting a lot of errors on the connection. We had one piece of
equipment, supposedly high quality, which destabalized about 1 or 2
GBICs per year (out of the 4 it used). We found that for that
particular equipment, the mid-priced generic brands lasted as well or
better than fully-branded expensive GBICs. In the same time frame,
we ran a completely different set of equipment for years and had
at most 1 (of 8) GBICs have problems -- only 1 over several years,
whereas in the first set of equipment with fewer GBICs, some GBICs
went bad every year.
If you are using copper GBICs, be careful: they can draw more power
than the maximum that was specified in the original GBIC standard.
If you are using older equipment that was not designed to be able to
supply the higher current, then your results might depend upon exactly
which slot you plug the copper GBIC in to, and on exactly what else
you have connected -- some slots might be able to provide marginally
more power than others.
Also, our networking specialists at HQ have done some testing, and only
recommend using the Finisar copper GBICs on the Nortel equipment they
have tested against; the Finisar happens to be the one that Nortel
themselves recommend for the devices my HQ was testing.
[If you do happen to be looking for Finisar HSSDC copper GBICs, then
wierdstuff.com has used ones at the best prices I was able to find last
week, about $US40 each. I found one place that was selling apparently
new ones for about $US65 each. Other than those two, every other place
I looked was asking more than $US100 each -- as high as $US325 each at
one of the better-known online stores!]
In summary: sometimes you can get away with using inexpensive or
mid-priced GBICs, and sometimes you cannot, and there is no real
way to tell in advance what will work in any particular situation.
If you need high reliability, then *usually* you should go with
what the manufacturer recommends... but in some unusual situations,
less expensive GBICs can turn out to be more reliable than expensive
ones. If you are having problems with your GBICs, try other slots
before giving up on the GBIC -- and a GBIC that fails in one device
might work well in another. And always have a spare GBIC available.
GBICs problems are something you need to plan for -- you can't rely
on any one brand to always work, and you can't rely on any one GBIC
to keep working once it is in place.
--
"I want to make sure [a user] can't get through ... an online
experience without hitting a Microsoft ad"
-- Steve Ballmer [Microsoft Chief Executive] |
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in