Is this only happening in one direction? One possibility is that the
carrier has a different circuit that is provisioned up, HDLC, with no
physical connection. A short-circuit in a DACS or MUX is bridging the
transmit interface towards your destination with a transmit interface on
the unused but active circuit. This would cause your traffic in that
direction to fork both on the desired path and some rogue path that
eventually gets routed to your destination.
The ethernet equivalent would be a SPAN monitor port plumbed to a
transmit-only interface on a different network.
Definitely a strange one. If I'm correct, when the other circuit starts
to get customer traffic things will probably break completely for either
the new customer seeing your PPP traffic or for both of you.
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Jay Hennigan - CCIE #7880 - Network Engineering - [EMAIL PROTECTED]
Impulse Internet Service - http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV