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

Re: Unstable SS7 Links and G.703 Baluns

Scott Dorsey (kludge@panix.com)
4 May 2005 11:22:57 -0400

<sarkar.abhik@gmail.com> 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.

--scott

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

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