Nortel Networks 8000 - Manual (Page 279)

7 LAPB and X.25 configuration
Nortel Secure Router 8000 Series
Configuration -WAN Access
Fault analysis
The possible cause is that the maximum frame size of this end may be too small. Set a larger
value of maximum frame size.
Troubleshooting procedure
Do as follows on the routers:
Step 1 Enable the debugging. You can find that one end discards the received frames without
transmitting it to the X.25 packet layer.
Step 2 Modify the MTU on the end.
—End
7.9.3 X.25 Protocol cannot enter the up status
Fault description
LAPB is in "Connect" state, but the X.25 protocol cannot enter the "UP" state for a long time.
Fault analysis
The possible causes are:
• You have configured the local working mode incorrectly. That is, the working modes on
both the ends of a connection are the same. The modes may be DTE or DCE.
• The X.25 modulo settings are di^erent on two ends.
Troubleshooting procedure
Do as follows on the routers:
Step 1 Change operation mode of the interfaces.
Step 2 Modify the X.25 modulus.
—End
7.9.4 X.25 Protocol is up, VC cannot be established
Fault description
The X.25 protocol is Up, but the VC cannot be set up.
Fault dnalysis
The possible causes are as follows:
• The local X. 121 address is not configured.
• The address mapping to the peer is not configured.
• The opposite X.121 address is not configured.
7-76 Nortel Networks Inc. Issue 5.3 (30 March 2009)