General Troubleshooting Tips - ADTRAN Express L128T S User Manual

Chapter 4. Troubleshooting

GENERAL TROUBLESHOOTING TIPS

The following sequence of troubleshooting steps is usually the best
method of checking the connection. If more in-depth troubleshooting
is required, it may be necessary to contact ADTRAN Technical Sup-
port (see inside back cover).
To troubleshoot, it is usually best to verify layer 1, then layer 2, and
then layer 3.
1. Layer 1 WAN Operation: Verify that the ISDN circuit is
established by following the procedures listed previously in this
chapter. Look at the bottom bar on the menu screen to see if call is
connected on B1 and/or B2.
2. Layer 1 LAN Operation: Verify that the LINK LED is active on
the hub (if applicable) and the L128T S/T.
3. Layer 2 WAN Operation: Verify that PPP and associated control
protocols are established by looking in the Status/Call Session
menu for the following status.
A. Check to see if the LCP (Link Control Protocol) is up. If LCP
cannot converge, the other control protocols cannot be estab-
lished. Check the PPP settings of the devices at both ends of
the circuit. Make sure that the authentication setup agrees at
both ends.
B. If STAC compression is enabled, check whether CCP (Com-
pression Control Protocol) is up. If STAC is enabled and this
compression attempt failed, make sure that the called party
supports STAC LZS compression.
C. If BACP (Bandwidth Allocation Protocol) is enabled, check
whether BACP is up. If this failed, verify the called party sup-
ports BACP.
D. If Bridging is enabled in the connection list and on the Ether-
net, check whether BCP (Bridge Control Protocol) is up. If this
failed, verify that the called party supports bridging.
E. If IP Routing is enabled in the connection list and on the Ether-
net, check whether IPCP (Internet Control Protocol) is up. If
this failed, verify that the called party supports IP routing.
F. If IPX Routing is enabled in the connection list and on the
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