Optical signal question

[Blue)(Fusion]

I am a novice when it comes to fiber optics, but I finally got my "core rack" in the basement connected to my remote, stacked switches in the second story via an 8-fiber OM4 cable. The cable is connected to a patch panel and then 1-meter patch MM fiber cables from the patch panel to the switch at both ends of the link. The 5th connection seen below is a link to my desktop computer.

My core switch does not have the ability (that I could find) to show transceiver details, but the remote switch shows the following. Is this normal/okay?

(GSM7228PS) #show fiber-ports optical-transceiver-info all

                         Link Link                                 Nominal
                       Length Length                                   Bit
                         50um 62.5um                                  Rate
Port     Vendor Name      [m] [m]  Serial Number    Part Number     [Mbps] Rev  Compliance
-------- ---------------- --- ---- ---------------- ---------------- ----- ---- ----------------
1/0/25   JDSU               8    3 CA17FM1G3        PLRXPLSCS43811   10300 1          10GBase-SR
1/0/26   JDSU               8    3 CA19FM06W        PLRXPLSCS43811   10300 1          10GBase-SR
1/0/27   FINISAR CORP.      8    3 MWG1SDJ          FTLX8571D3BCL    10300 A          10GBase-SR
2/0/25   JDSU               8    3 CA17FM1CD        PLRXPLSCS43811   10300 1          10GBase-SR
2/0/26   JDSU               8    3 CA16FM0EF        PLRXPLSCS43811   10300 1          10GBase-SR

(GSM7228PS) #show stack-port

                                                Configured Running
                                                Stack      Stack      Link       Link
Unit    Interface     Type    Product Name      Mode       Mode       Status     Speed (Gb/s)
---- ---------------- ------- ----------------- ---------- ---------- ---------- ------------
1    0/25             SFP+    PLRXPLSCS43811    Ethernet   Ethernet   Link Down    10
1    0/26             SFP+    PLRXPLSCS43811    Ethernet   Ethernet   Link Down    10
1    0/27             AX743   FTLX8571D3BCL     Ethernet   Ethernet   Link Down    10
1    0/28             AX742   (stack)           Stack      Stack      Link Up      12
2    0/25             SFP+    PLRXPLSCS43811    Ethernet   Ethernet   Link Down    10
2    0/26             SFP+    PLRXPLSCS43811    Ethernet   Ethernet   Link Down    10
2    0/27             AX743                     Ethernet   Ethernet   Link Down    10
2    0/28             AX742   (stack)           Stack      Stack      Link Up      12

(GSM7228PS) #show fiber-ports optical-transceiver all

                                    Output    Input
Port      Temp  Voltage  Current     Power    Power   TX     LOS
           [C]   [Volt]     [mA]     [dBm]    [dBm]   Fault
--------  ----  -------  -------   -------  -------   -----  ---
1/0/25    28.3    3.295      6.9    -1.608   -1.513   No     No
1/0/26    26.6    3.296      6.9    -2.327   -2.175   No     No
1/0/27    33.4    3.373      8.0    -2.543   -2.061   No     No
2/0/25    27.4    3.308      6.6    -2.114   -2.297   No     No
2/0/26    27.4    3.309      6.7    -1.996   -3.157   No     No

 Temp - Internally measured transceiver temperatures.
 Voltage - Internally measured supply voltage.
 Current - Measured TX bias current.
 Output Power - Measured optical output power relative to 1mW.
 Input Power - Measured optical power received relative to 1mW.
 TX Fault - Transmitter fault.
 LOS - Loss of signal.

 

[fohdeesha]

you're all good fam, fully slammed rig

generally you want to stay above -7dbm, and you're well above that. -1 is about as good and clean as it gets. You can check the datasheet for your specific optic transceivers and they'll have exact recommended numbers and working minimums

 

[fohdeesha]

Here's the appropriate section pulled from the sheet of your PLRXPLSCS43811 optics. As you can see you're well above the -7.5dbm stressed sensitivity minimum, which is the lowest received light level it must still operate at with a certain acceptable bit to error ratio. -7.5dbm is mandated by the IEEE for 10gbase-SR optics, hence the generally staying above -7dbm being a good idea regardless of the optics manufacturer

 

[Evan]

Why did I have it in my mind the little link loss budget was -4.5db, or maybe that’s the tighter standards we use internally. Either way your well fine enough as the others have pointed out.

 

[fohdeesha]

-4.5db is certainly a good goal to shoot for, considering -7.5 is typically the bare minimum it's never a good idea to ride that line

 

[Evan]

-4.5db is certainly a good goal to shoot for, considering -7.5 is typically the bare minimum it's never a good idea to ride that line

For context that is always in the same room which is smallish (120 racks max size) and at most you have a patch cable at either end of the infrastructure cabling. Allow 0.3db (ideal less than 0.18 which is new standard) per patch panel connection or splice.

I certianly want to keep it pretty tight as 40G bidi now but from now on 100G bidi.

 

[Blue)(Fusion]

Awesome and thanks for the info, gents! I kept looking up loss specs for the switches but didn't think that the optic transceiver is what I should have been looking up.