- The Tx and Rx lights on all SFP ports are not data lights, rather they are clock lights and as such only light when you're dealing with synchronous broadcast signals - HD/SDi, MADI, AES etc.
- The CWDM multiplexer/de-multiplexer (they are exactly the same unit!) works both ways and if you have signals going bi-directionally on a fibre each port is an input or an output; that takes a bit of getting your head around!
- In a similar vein the wavelength quoted on SFPs (1350nM in this image) only really applies to the transmitted signal; SFPs are "colourblind" - they don't mind what wavelength they receive. So, once a signal leaves the CDWM de/multiplexer you can take it into any of your SFPs for input to the crosspoint router - again, it's not particularly intuitive as we're used to "tuning" or "demultiplexing" other signals to the frequency they'll be used at.
- The BarnStudio software; the manual says that it comes set up hard-set to a 192.168.0.1 address; our didn't, it was setup for DHCP and since it doesn't respond to multicast PINGs it took me a while to figure this out.
- If you are routing ethernet out to the multiplexer it is always directional (i.e. it takes up the in and out of an SFP and needs two ports on the multiplexer).
- See note 1 above (no activity lights) for ethernet.
- If you're using the same machine to drive BarnStudio and test an ethernet connection (by sending it via an ethernet SFP -> fibre -> multiplexer -> BarnMini -> SFP -> ethernet) you run the risk of an ethernet loop and subsequent broadcast-storm! Wesley & I suffered this and couldn't figure out why the entire workshop network was down. Much better to use your rucksack router & a RaspberryPi as a separate test network.
- The BarnStudio software - although good, is a tad hard to read initially as if you give the ins and outs proper names they re-order alphabetically rather than in order of the SFPs and BNCs. Just remember - inputs are down the left axis and outputs are along the top (most things are present in both).
Wednesday, September 10, 2014
Ongoing Barnfind notes
As I get more familiar with Barnfind's products I need to make a note of some of their gotchas!