Unsupported SFP support on Catalyst 2960S and 3750

Hi all,

I'd be looking for any experience on the use of 'service unsupported-transceiver' on the following boxes:

Specifically: working/not, what IOS version, what transceiver type/model, etc.
Somehow I didn't find a nice support matrix for it on the Cisco site...
Please don't tell me it's not recommended and all, I know that. ;)

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TimotiStDatacenter TechnicianAsked:
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IOS version - should work from 12.2(25)SE
Fiber Optic Equipment Solutions | Fiberstore
TimotiStDatacenter TechnicianAuthor Commented:
Thanks, the reason I've asked for actual experience is that 'should' is not enough to start buying for a client. :)
Checked the two links, couldn't find any info on them about the Catalyst models in question.
My company use only Cisco SFPs in Cisco switches and sometimes even brand new Cisco SFPs do not work, but if they do usually don't get broken. One of my colleagues told me that he bought some SFPs and those worked (most of them about 2 months or so), so that experiment failed. Client will blame you if/when there are problems. If you save them money and everything works no one cares. I don't think it's worth to risk your reputation over it.
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TimotiStDatacenter TechnicianAuthor Commented:
Thanks, noted.

Anybody with experience?
Garry GlendownConsulting and Network/Security SpecialistCommented:
"service unsupport-transceiver" is helpful in a pinch, though the results may greatly differ between different SFPs. E.g., for a current update of the IOS (15.3/4 I believe), coding has been changed, so even some Cisco-coded OEM SFPs that worked fine before stopped working - specifically, they even are still recognized, but the link will not come up. The unsupported-transceiver feature doesn't fix it, either.

My recommendation is to find a decent reseller that supplies specifically Cisco-compatible SFPs, for the devices you want to use them in, and will allow you to return and replace them if they do not work. They might be a buck or two more expensive, but that way, you and your customer will have some peace of mind there ... this has worked for us the last 10+ years ... and paying 4-10x the price just to get the same f'ing piece of hardware from the same manufacturer just with a different sticker on it does not make the original SFPs work any more reliably ...

Oh, and durability isn't a problem either with our suppliers - we must have used and re-sold at least something like 500-800 1G and a couple dozen 10G SFPs from the two suppliers over the last 10 years, and out of all of them, I know of only one (1!) that has had a hardware failure ... YMMV, of course ... problem is, without some past experiences with a supplier, it will be harder to judge whether you have a decent supplier or not ...

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Here's the deal.  You MUST only use SFPs that are on Cisco's qualified list.  No substitutions.  That isn't just for Cisco, they go for Fibre-channel attached storage as well.  SFPs are radically different even though specs "seem" to be the same.    I've been a storage architect for 25 years and will spare you the all the differentiators.  You can go to any of the manufacturer's websites and look at the data sheets for a SFPs and see how much they differ.  (Try:   http://www.globalsources.com/manufacturers/SFP-Module.html)

I really don't see why you have problems.  I googled "Cisco certified SFP WS-C3750G-12S" and the link below came up that listed the Cisco part numbers.   Just buy the Cisco labeled one for the appropriate distance and cable type and be done with it.

Garry GlendownConsulting and Network/Security SpecialistCommented:
Not wanting to start a discussion about vendor policies, but ... Yes, that is true, any vendor will always very clearly advise you to only use that vendor's original, certified SFPs, as this will prevent the hardware from failing 100% of the time ...

Yes, right. A couple years back, HP I believe it was published some updates for their switches, which caused older, original-spec SFPs to be recognized as non-HP-SFPs ... so much for reliability.

I do understand EVERY customer who will - rightfully - ask why a simple 1G SFP will be charged at three- and four-figure prices, while OEM/compatible are offered at sometimes a tenth of the price.

Well, if vendors like Cisco would start charging somewhat more sensible prices, less customers would go out and buy OEM ... just pulled these from a Cisco reseller page, all parts listed are original Cisco SFPs

* 1G MM - list price 444€, reseller price 268€
* 100M (!) MM  - LP 355€, RP 214€
* 1G BiDi SM - LP 1155€ RP 698€
* 1G TX - LP 391€ RP 201€
* 10G MM - LP 884€ RP 532€
* 10G SM LR - LP 3549€ RP 2136€

Please do explain how a piece of hardware that has been identically manufactured by maybe half a dozen or dozen different manufacturers world wide and sold as OEM - partly with the correct coding and tested to work in a device - for anywhere between 25-30€ (1G SFPs) and 100-150€ (10G SM) is marked up 10-20 fold? Even considering rigorous testing and higher rejects quota, that amount of price-increase is way over the top ... so, unless vendors like Cisco stop over-charging stuff like SFPs, people will keep on going out and look for cheaper, more sensible replacements. At least any customer that does not use tax money to buy their stuff. And as for perceived or supposed earlier failure - just pick up a hand full of extra SFPs, keep them on site, even with those extras, you'll come out well below the originals SFPs ...
SFPs are PROGRAMMABLE just like HDDs are programmable.   I'm sure it is no surprise that any particular model of Seagate SAS HDD is OEMed by IBM, HP, Dell, and EMC to name a few.  But those drives have different operational characteristics.

So there you have your reason.   Same physical component from manufacturer ... but different operational characteristics.   That is why you buy the Cisco SFP.  It is programmed to behave differently, just like disks are tuned.

(And no, you just can't reprogram them and reverse engineer with software, you need to buy some expensive equipment, and getting into those details would probably violate TOS by explaining further.   Suffice to say with 25+ years experience in this, SFPs ARE DIFFERENT, AND YOU MUST GET THE CORRECT P/N FROM THE MANUFACTURER, unless you have 100% confidence they are using a stock product.  There are ways to determine if it is an unmodified SFP EEPROM but again TOS issues and outside the scope of this discussion).
I got some CX4 cables from my storage array vendor and were able to get them working with my Cisco 6509 by using the "service unsupport-transceiver" command. For all the others, I have bought used Cisco SFP and SFP+ optics, which are usually cheaper than new third party optics.

I am looking at buying new gear for a new building, and after looking at the pricing for optics it made me wonder if optics would be the majority of the cost.
The "service unsupport-transceiver"  basically just says to suppress error/warning messages.  It doesn't change how it works.

Now buying used is a reasonable thing to do.  But remember that most SFPs are limited to around 50 insertions, and you have no idea whether or not the ones you buy have any dust or scratches on the optics.

Furthermore, read the fine print on the support/warranty documentation.  Using 3rd-party SFPs can disqualify you from support IF you have a problem that can be traced to SFPs.    (I.e, performance/connectivity issues).

IN grand scheme of things, considering how much money you pay for the Cisco equipment and the hardware that the Cisco units plug into, just buy the darn product that Cisco spends hundreds of thousands of dollars certifying.   The money you save isn't statistically significant.
TimotiStDatacenter TechnicianAuthor Commented:
@kevinhsieh: thanks for the idea about used Cisco originals, I didn't really think about that.

@dlethe: thanks for the warnings and all, but as the original question said, I'm well aware of these issues and disregard them at the moment. The client has existing Cisco gear. They used to have the big bucks to buy them, they don't anymore and I need to extend their network. I would love to buy genuine ones to cover my arse, but not an option. I'll let them know what they are buying, the risks, etc. Nothing is under warranty/support anymore.

@Garry-G: do agree on the overpriced part. I'm working for a very very big networking company as well who buys brand new Cisco Nexus/ASR with OEM 10G optics because of the price point. They die like flies, we have a 10% failure rate, but are still well within money with them.

Original question stands: please give me model numbers of 1G optics, that is known to work with the above switches, preferably with IOS version to go along with.

Cisco does NOT use stock unmodified SFPs.  They reprogram them.  So the official answer is that what you ask for doesn't exist.
The command is available.  This is the result when used.

config t
(config)#service unsupported-transceiver
 Warning: When Cisco determines that a fault or defect can be traced to
the use of third-party transceivers installed by a customer or reseller,
then, at Cisco's discretion, Cisco may withhold support under warranty or
a Cisco support program. In the course of providing support for a Cisco
networking product Cisco may require that the end user install Cisco
transceivers if Cisco determines that removing third-party parts will
assist Cisco in diagnosing the cause of a support issue.
" ...  They used to have the big bucks to buy them, they don't anymore and I need to extend their network."

In other words, they are doing the equivalent of running 1GigE over CAT6, and now can't afford that cable, and they want you to suggest a less expensive CAT5 cable that will reliably do 1GigE.

It is the same thing.  Man up and tell the customer that they need to purchase the right tool for the job, which is new or (gently) used Cisco SFPs.   Final answer.  SFPs ARE PROGRAMMABLE.  CISCO PROGRAMS A FEW OFF-THE-SHELF SFPs for proper timeouts, retries, voltage thresholds, delays, etc..   That is one of the reasons why Cisco networks are so fast & reliable compared to other solutions.  They tune and certify connectivity to minimize errors and dropped packets.  The low-cost vendors do not.

If they value their data they need to save money elsewhere and buy the right product.
TimotiStDatacenter TechnicianAuthor Commented:
@dlethe: appreciate your comments, but as in the original question, I'm not here for the morals this time. I also can't magically create money for their budget, either.
It isn't morality, it is suitability to do the job.  You seem to believe that the difference is hardware alone.  It isn't.  The difference is also firmware, as such, the difference is operational characteristics that are programmed into SFPs.

SFPs are not passive devices.
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