[AusNOG] 3rd Party SFP+ Optics

[Glen Turner]

[not speaking for my employer, whomever that may be]


Reasons for using third-party optics:

1. Purchase price

2. Quality. You don't know who the device vendor is using this week. If you buy Finisar you know what you are getting.

3. Wider range of optics, available when they appear on the market, not years later. This reduces downstream costs (eg, avoiding additional 3R to alter frequency prior to entering a WDM system). I am often finding myself selling our SFP+ to our customers because their vendor doesn't offer a particular optical option yet.

4. Support. If you have an optical issue the equipment vendor simply isn't interested. It's bread-and-butter for optical vendors. So if you need to use older optical plant then third-party SFP+ are really the only choice, simply so you can have sufficient assurance of the optical-level design. On the same theme, you get the correct optical data sheet, not some manufacturers' purchasing specification. This is particularly important if you need to account for advanced optical effects such as dispersion modes. Because device vendors want to retain their flexibility to change supplier most device vendors simply don't offer the longer distance SFP+ (where you need to account for advanced optical effects). So a reasonable metro design is often only possible with third-party optics.

5. Ability to re-write EEPROM in the field:

 5a) simplifies sparing, you only need one 10GBase-LR, one 10GBase-SR to spare Cisco, Juniper, HP, etc. Furthermore, you know the spare is exactly the same part, not merely a similar part with the same label. So you can validly compare current draw and other DOM information before and after the SFP+ replacement.

 5b) same SFP+ used before and after a device vendor change, therefore optical power budgets do not need to be recomputed, totally avoiding possible need to visit customer site to alter attenuation.

 5c) reduces costs when changing vendors of the device as optics do not need to be repurchased

6) Quantity. You ask a vendor for 200 SFP+ you can be waiting months. A optics vendor will ship you ten trays without drama. Without individually packaging them at your expense.

7) Features. Eg: you can buy tuneable optics now, but few equipment vendors are offering them yet. Similarly with 40GBase-WDM. Price also feeds in here (eg: if you have a STM16 slot you want to run STM4 from then you can afford to use STM16 SFPs and program them for STM4. When in a number of years time you upgrade from STM4 to STM16 you don't need remote hands and you have a simple fallback plan. Of course the STM16 SFP has to be cheap enough to buy now.)

8) Commonality. You can buy a 10GBASE-LR XENPAK or you can buy a XENPAK/SFP+ adaptor and a 10GBASE-LR SFP+ for much less. You really don't want to buy additional superseded XENPAKs just to have them available for sparing; whereas you've got a SFP+ for sparing anyway, so it's not a big ask to buy a XENPAK/SFP+ adaptor to be able to spare all types of XENPAKs.

-glen