Avaya Troubleshooting Routers Guide de dépannage télécharger pdf (Page 131)

Troubleshooting a Network Connection Problem

6-25

Refer to one of the following sections, if it applies to the problem:

•“Master Cannot Connect to Sla

ve”

•“T

roubleshooting RS232 Raise DTR Dial (Unbalanced)”

•“T

roubleshooting V.35 Raise DTR Dial (Balanced)”

•“T

roubleshooting ISDN BRI and PRI”

Master Cannot Connect to Slave

In a dial backup application, if the master side cannot make the connection to the

slave side, do the following:

1. Make sure the conﬁguration ﬁle is correct.

2. If the connection is V.25bis, check the log for the CRN.

3. Try reversing the master and slave.

4. Make sure that you enabled BOFL on the primary link.

If you can establish this connection, recheck the conﬁguration of the modem and

router.

Troubleshooting RS232 Raise DTR Dial (Unbalanced)

If DTR is up on the backup circuit (the master end), causing the backup modem to

dial even though the primary line is up, do the following:

1. Verify whether the modem is sending a DSR (data set ready) signal to the

router interface in the on state (positive voltage) when the local and

remote modems are not connected.

If it is, conﬁgure the modem for DSR to follow CD (Carrier Detect), or

conﬁgure DSR to be in the off state until the modem receives a DTR (data

terminal ready) signal. Unfortunately, DCE manufacturers use inconsistent

terminology for these settings.

When the router detects that DSR is in the on state (that is, receiving positive

voltage), it brings DTR high regardless of the state of the primary line. This in

turn causes the modem to dial. If the router does not see any DSR (0 voltage),

the router will also bring DTR high. This in turn causes the modem to dial.

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Avaya Troubleshooting Routers Guide de dépannage Page 131