Friday 23 September 2016

fibre optic cables

fibre cables have different terminations. You need to select the right cable which can connect to your deivce and the the other end to fiber patch panel so you need to check both. Some times the cables are mixed up in the patch so you need to pop the cables out and swap them around

ST (straight tip)
SC (Subscriber connector)
LC (Local connector)
MT-RJ 

LR = long range / single mode

SR = short range / multimode

Have seen 10g LRM SFPs work on both multimode/singlemode cable.


You need to see how it is terminated at each patch point.
You need to have the correct SFP in your network device so you can plug the fibre in.
You also need to select the right cables SC-LC, ST-ST etc.

Look a bit into the SFP you should see a light on one side. This is the trasmit side and needs to be the same all the way. You won't be able to see the light with single mode (its too narrow for the human eye). Need to use  device db signals

-> red light transmit
<- no light receive

There are OM values that relate to cable distance will update more on that later

10Gig-Base-SR (closer to 0 is better)
Typical working transmit range: -1 to -7
Typical working transmit range: -1 to -9.9

When we see a Rx power around -14 dBm or lower there is typically some sort of fault in the cable plant (bad splice, dirty connector, poorly seated jumper etc.) that's causing excessive signal loss.

If either Tx or Rx is in the -30 dBm or lower range that's usually indicative of there being no actual signal received and the transceiver is reporting the "noise floor" of the receiver stage. (https://en.wikipedia.org/wiki/Noise_floor)


https://www.cisco.com/c/en/us/products/interfaces-modules/transceiver-modules/index.html

CLI commands:

Router:

sh hw-module subslot 0/0 transceiver 2 status

sh hw-module subslot 0/0 transceiver 2 idprom

Switch:

sh int g1/0/1 status

sh int gig1/0/1 capabilities

sh int gig1/0/1 transciever

 

Monday 19 September 2016

Let cisco switch use 3rd party SFPs


Cisco SFP 
Left side = transmit
Right side = Recieve
http://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/installation/note/78_15160.html


Commands to allow using non Cisco SFPs
service unsupported-transceiver
no errdisable detect cause gbic-invalid


taken from:
http://www.firewall.cx/cisco-technical-knowledgebase/cisco-switches/866-cisco-switches-3rd-party-sfp.html

Check your sfp
sh int gigabitEthernet 0/3 status 
sh int gigabitEthernet 0/3 capabilities (check type)


Thursday 8 September 2016

VPN uptime

See how long a VPN is up
show vpn-sessiondb l2l filter name x.x.x.x