Troubleshooting ISDN Connections - Internetworking Troubleshooting - page 488

Note 2 : Having determined that the inbound traffic is actually an LCP packet, the access server triggers
the PPP negotiation process.
Note 3 : The async interface changes state to up, and the PPP negotiation (not shown) commences.
If the call is a PPP session, and if async mode dedicated is configured on the async interface, use the
command debug ppp negotiation to see whether any configuration request packets (the debugs will
show them as CONFREQ) are coming from the remote end. If PPP packets are seen to be both inbound
and outbound, proceed to the section “PPP Debugging.” Otherwise, connect in from the call-originating
end with a character-mode (or “exec”) session (that is, a non-PPP session).

If the receiving end has the setting async modem dedicated under the async interface, an
exec dial-in will see nothing but what appears to be random ASCII garbage. To allow a
terminal session and still have PPP capability, use the async interface configuration
command async mode interactive . Under the associated line's configuration, use the
command autoselect ppp .

Note