TELECOM Digest OnLine - Sorted: Re: Unstable SS7 Links and G.703 Baluns

Re: Unstable SS7 Links and G.703 Baluns

Scott Dorsey (
4 May 2005 11:22:57 -0400

<> wrote:

> The links work fine most of the time. But, occasionally all the E1
> links on the Cisco SS7 equipment go down. We haven't yet found what
> causes the problem. Usually the only way for the links to come up is
> to reboot the equipment or sometimes to shutdown and startup the E1
> controllers.

> We have some connections going straight to another SS7 equipment
> through a couple of baluns. We suspect these connections might be
> causing some problem because we haven't got the grouding configuration
> correct for the balun's involved in these connections. Ever since we
> have disconnected these connections the problem seems to have
> vanished.

> Can someone suggest anything or has someone seen any problem like this
> before?

This sounds like a typical ground loop problem to me. Get out the
scope and start looking for 60 Hz trash on the balanced lines. I bet
you see some problems.

Everything should have one and only one path to the central ground.
Never none and never two.


"C'est un Nagra. C'est suisse, et tres, tres precis."

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