question on "hoot & hollar" or multicasting 1

[macphoneguy]

I have a system that uses vic2-E&M ports to mulicast some audio from one building to three others, the audio is all one way, and every once in a while, it seems we Loose something, ( I don't really know what) the only symptom is that the audio level goes from 1-2 Millivolts rms to 9-10 volts RMS or -50 DB range to the -30 range, re-booting the router either locally or remotely seems to solve the problem until the next time it happens
I'm "guessing" that it is some kind of "Ground loop" problem but since not readily repeatable I'm not sure
the systems themselves are on UPS's that are also grounded to the same ground, nothing in the logs of the ups or the router indicate anything, any thoughts are appriciated

 

[whykap]

is there a call manager in the picture or just the router doing voip?
What type of router?
What is the exact ios version currently running?

 

[macphoneguy]

no, it is just a collection of routers, connected to some switches, there is a whatsup box monitoring the ip's but that's about it

 

[whykap]

what type of router and what's the IOS version?

 

[burtsbees]

What is generating the audio?

Burt

 

[PeterHurst]

Sounds like a problem with the encoding in the VIC as you say - it's hard to say if it's hardware of firmware.

Easiest tests are to swap the VIC and check all connections - earth potential could be an issue. Check that the device sourcing the E&M is bonded to the same earth as the Cisco (and I mean the real earth not the mains plug). Also don't forget that signalling earth in E&M is not necessarily bonded to ground (often it is in my experience) but it's also worth making sure E&M signalling ground is correctly connected.

If that doesn't help you're in the realms of IOS/Firmware on the Cisco but also there may be problems with the switch generating the signal so don't forget to look there. Is there an option to use a digital mechanism even if it's only BRI trunks or something??

 

[macphoneguy]

well I know at one of the locatons, I know the earth ground's are Not at the same spot and I will be putting a hunk 12 awg wire to "fix" that problem,
as I know in another instance, I had a motor that when on it made enough ground noise to cause a problem for a DSL box so I'm suspecting something along that line Might be the case here, especially since it is interment I'll have to check the other locations

 

[burtsbees]

Hell, if you suspect a motor, you could put a freq meter on a water pipe (ground) and the hot on the circuit that you pludg the router into. Earth ground is earth ground...

Burt