Optical Network Configurations

[jabbr]

7 hours ago, The Computer Audiophile said:

I hear you 100%. But, the faster the interface the less TIME it is used. I don’t know if faster interfaces have more noise due to higher speeds. No clue. 

 

The faster interfaces are *required* to have much less noise despite the higher speeds. The technical requirements become nothing short of magic.

[The Computer Audiophile]

1 hour ago, jabbr said:

 

The faster interfaces are *required* to have much less noise despite the higher speeds. The technical requirements become nothing short of magic.

Less noise on the line but what about power requirements for the phy?

[lmitche]

46 minutes ago, The Computer Audiophile said:

Less noise on the line but what about power requirements for the phy?

Yesterday, my transceivers were "upgraded" from fs.com SFP+s to finisar SFP+s. The only difference in spec is that the fs.com SFP+ is also compatible with 1gbps Intel NIC cards. The difference in SQ was quite a surprise. The finisars deliver much more harmonic detail and PRAT. A friend gave me this tip otherwise I'd have never done this. @ray-dude is correct, this change was based on empirical evidence. Also, with used finisars available at $12 each on Ebay, there was little to lose.

 

This was after "upgrading" from a 850nm MM to 1310nm SM SFP+. That was also a surprising jump in SQ. My understanding is that the MMs use leds, not true lasers, so that may cause the difference in SQ.

 

And yes, faster communications means less power demand, but there are many places in my system where things sound better with green enhancements switched off.

 

We talk a lot about power supply, but not enough about power demand.

[FIndingit]

Finisar SFP+ 1310nm are much more than $12 at the moment. Lots of cheap Finisar SFP 850s on the other hand. 

[lmitche]

2 hours ago, FIndingit said:

Finisar SFP+ 1310nm are much more than $12 at the moment. Lots of cheap Finisar SFP 850s on the other hand. 

Hi NOT FIndingit,

 

They are right there on the ebay US site. Keep looking.  Clue: there are white label Avago models as well of the same spec.

 

 

[jabbr]

13 hours ago, lmitche said:

Yesterday, my transceivers were "upgraded" from fs.com SFP+s to finisar SFP+s. The only difference in spec is that the fs.com SFP+ is also compatible with 1gbps Intel NIC cards.

 

There are dual speed Finisars 10/1gbs and what I use.

 

Let's see this one is a dual single mode: https://www.finisar.com/sites/default/files/downloads/finisar_ftlx1475d3bcv_10g-1g_dual_rate_10gbase-lr-lw_1000base-lx_10km_1310nm_single_mode_datacom_sfp_optical_transceiver_productspecrevb1.pdf

 

I am a huge fan of Finisar.

[jabbr]

14 hours ago, The Computer Audiophile said:

Less noise on the line but what about power requirements for the phy?

 

The 10gbe and faster serdes/asics maintain the very tight noise requirements *end-to-end* not just on the line. The specs are very demanding. Aside from networks, the eye pattern requirements for PCIe-4 are such that, for example, Intel is not yet able to meet despite the CPU being "enabled" ... its the low noise system requirements that have been giving the Intel platform trouble... I mention 10Gbe and up because that spec was the first to impose the end-to-end testing requirement, so-called "stressed eye pattern" testing.

 

This is a nice discussion from Tektronix (not just my pontification  )

 

65W_26049_0_Letter_0.pdf

[The Computer Audiophile]

5 minutes ago, jabbr said:

 

The 10gbe and faster serdes/asics maintain the very tight noise requirements *end-to-end* not just on the line. The specs are very demanding. Aside from networks, the eye pattern requirements for PCIe-4 are such that, for example, Intel is not yet able to meet despite the CPU being "enabled" ... its the low noise system requirements that have been giving the Intel platform trouble... I mention 10Gbe and up because that spec was the first to impose the end-to-end testing requirement, so-called "stressed eye pattern" testing.

 

65W_26049_0_Letter_0.pdf 5.5 MB · 1 download

Very cool. 

[barrows]

28 minutes ago, lmitche said:

Hi NOT FIndingit,

 

They are right there on the ebay US site. Keep looking.  Clue: there are white label Avago models as well of the same spec.

 

 

Or, they could be counterfeit.  Do not underestimate the possibility of Chinese counterfeit products at "too good to be true" prices on eBay.

[jabbr]

3 minutes ago, barrows said:

Or, they could be counterfeit.  Do not underestimate the possibility of Chinese counterfeit products at "too good to be true" prices on eBay.

 

Its common to find counterfeit Intel NICs and folks should look for the blue Yottamark tag ... there are Mellanox cards missing the proper stickers on the back ... overall I've had terrific luck on eBay and less likely counterfeit *used* equipment typically sold by high volume used equipment vendors, than *new* products source from China at new good to be true prices... 

 

Finisar is essentially an optics OEM which supplies to the major network vendors. Finisar actually makes the SFP!. I haven't personally encountered a counterfeit on eBay. Brands such as Startech almost certainly some OEM -- who knows they might use Finisar but I have no experience, I have no idea which OEM they use.

 

fs.com is a great supplier. 

[jabbr]

4 hours ago, jabbr said:

products source from China at new good to be true prices... 

 

*products sourced from China at too good to be true prices ...

 

😂🤷‍♂️

[plissken]

4 hours ago, barrows said:

Or, they could be counterfeit.  Do not underestimate the possibility of Chinese counterfeit products at "too good to be true" prices on eBay.

 

Or you should be able to hear the difference, no?

[plissken]

4 hours ago, jabbr said:

fs.com is a great supplier. 

 

Only issue with FS is shipping speed. I just received 280 SR LC's and it took 5 weeks. 

[jabbr]

14 minutes ago, plissken said:

 

Only issue with FS is shipping speed. I just received 280 SR LC's and it took 5 weeks. 

Yeah but $12 for 30m lc-lc single mode?

 

The big win for single mode, aside from optics, is that the same cable can be used from 1Gbe -> 100Gbe, i.e. the cables are much cheaper and offset the increased price of optics.

[The Computer Audiophile]

3 minutes ago, jabbr said:

Yeah but $12 for 30m lc-lc single mode?

 

The big win for single mode, aside from optics, is that the same cable can be used from 1Gbe -> 100Gbe

I get these single mode cables. Free 2 day shipping. 
 

https://www.amazon.com/gp/aw/d/B01MYOJVKD

[plissken]

3 minutes ago, jabbr said:

Yeah but $12 for 30m lc-lc single mode?

 

The big win for single mode, aside from optics, is that the same cable can be used from 1Gbe -> 100Gbe, i.e. the cables are much cheaper and offset the increased price of optics.

 

Not my call. Existing campus cabling is all MM and they aren't going to spend $1.2 million pulling new SM. Any new fiber is SM thankfully. 

[The Computer Audiophile]

Question for you guys, what’s difference between bi-directional single mode on a single wire and duplex single mode on dual wire?

[jabbr]

6 minutes ago, The Computer Audiophile said:

I get these single mode cables. Free 2 day shipping. 
 

https://www.amazon.com/gp/aw/d/B01MYOJVKD

 

You want DUPLEX cables though, unless you are listening to mono recordings? 😂

 

jk, you want DUPLEX cables ... and yeah no problem as these go up to 10m. fs.com offers really cheap prices on custom lengths. For example I go with 3.0mm jackets which are much sturdier when pulling through walls.

 

2 minutes ago, The Computer Audiophile said:

Question for you guys, what’s difference between bi-directional single mode on a single wire and duplex single mode on dual wire?

 

The SFP(+) modules use duplex single mode (or duplex multimode)

[The Computer Audiophile]

1 minute ago, jabbr said:

 

You want DUPLEX cables though, unless you are listening to mono recordings? 😂

 

jk, you want DUPLEX cables ... and yeah no problem as these go up to 10m. fs.com offers really cheap prices on custom lengths. For example I go with 3.0mm jackets which are much sturdier when pulling through walls.

But my SFPs are BiDi single wire. Isn’t that the same thing on one wire?

[The Computer Audiophile]

[jabbr]

7 minutes ago, The Computer Audiophile said:

But my SFPs are BiDi single wire. Isn’t that the same thing on one wire?

OK! Those are much much less common. Still works, just not anything we have talked about nor recommended here, but that works for your specific SFP module.

 

We have talked about these modules

 

1000Base-SX -- duplex multimode 1Gbe

1000Base-LX -- duplex singlemode 1Gbe

10GBase-SR -- duplex multimode 10Gbe

10Gbase-LR -- duplex singlemode 10Gbe

 

and you are using either of:

1000base-BX -- simplex singlemode 1Gbe (BiDirectional)

10Gbase-BX -- simplex singlemode 10Gbe

 

I just want to keep this straight for folks, in all cases your SFP modules need to match at each end (in terms of type not necessarily brand) and the cable used needs to match the type of SFP module

[plissken]

16 minutes ago, The Computer Audiophile said:

But my SFPs are BiDi single wire. Isn’t that the same thing on one wire?

 

SR/LR modulates TX on one strand and RX on another.

 

LC BiDi modulates Tx and Rx on each strand.

 

Many times when I'm wiring SM/MM OM3/OM4 for LC applications I have to take the cabling out of it's retaining clip and flip (crossover) the connectors and I get my link to go. 

 

I don't have to worry about this on LC BiDi. It's also way more cost effective and less error prone than MPO especially when we are doing QFSP over two strand SM cabling. 

[plissken]

Chris makes a good point to bring up LC BiDi as it simplifies everything.

 

They are $36 at FS.COM. Even considering that 10GB LC modules are ~$21, for another $30 (two modules) and only needing a single SM cable strand it makes setup for people just getting into this dead simple. 

[lmitche]

20 hours ago, lmitche said:

Also, used finisars available at $12 each on Ebay

6 six pieces of used finisars 1310nm SPF+ are still available on Ebay at $12 each,

 

6 hours ago, barrows said:

Or, they could be counterfeit.  Do not underestimate the possibility of Chinese counterfeit products at "too good to be true" prices on eBay.

Barrows, counterfeit or not, they sound better than the fs.com SFPs they replace.

[plissken]

12 minutes ago, lmitche said:

6 six pieces of used finisars 1310nm SPF+ are still available on Ebay at $12 each,

 

Barrows, even if they are counterfeit, they sound better than the fs.com SFPs they replace.

 

What setup are you able to hear these real-time differences on?