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Why Would an X.25 Serial Interface Be Up/Down during send and receive Data over X.25/XOT?

Why Would an X.25 Serial Interface Be Up/Down during send and receive Data over X.25/XOT?

Scenario:

PC===Cisco2501/X.25===V.24-Modem==<>==V.24-Modem====Cisco2522/X.25====XOT-Tunnel====MainframeBS2000

There is the Situation that after a while the Int-S1 on Cisco2522/X.25 sets the Line-Protocol down,

then the Interface down. After ca. 5 seconds the Interface comes up. In betweentime the client-PC requests

the X.25-Call to the Host. When Interface is up the Call will be initiated, Connection is up.

There are no errors occured in the syslog or in debug-mode.

1 REPLY
Anonymous
N/A

Re: Why Would an X.25 Serial Interface Be Up/Down during send an

The problem could be physical or

at layer2 (LAPB). If we lose connectivity

at layer2, for whatever reason,

LAPB will try to restart itself (by

sending a SABM) and if we don't receive

a UA the line protocol will go down.

You can have a look at "debug lapb"

to see if this indicates a problem;

also check out the interface stats to

ensure there are no errors or drops.

Finally, you might ensure the configs

of the V.24 modems, to verify that they

are configured the same (since it sounds

like one end has a problem, the other

doesn't).

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