Configuring the Point-to-Point Protocol (PPP)

Testing automatic dialup connectivity

Verify host-to-host connectivity on the link as follows:

Turn on the PPP driver, PPP daemon, and UUCP logging. See ``Logging PPP information''.
Execute the following command:

ping remote_host_IP_address

If ping fails, it may fail with an error message. Below is one possible message:

   ping send: Network is unreachable

This error message indicates that the network address of the remote host is different from that of the local host. Make sure that the network portion of the remote host's IP address is correct. (See ``IP address'' for a discussion of the network portion of the IP address.) For machines on the same network, the network part of the IP addresses for the local host and the remote host should match. If the machines are not on the same network, you need to configure a gateway to route packets between the two networks.

Another possible message is:

   ping send: No route to host

If this message appears, verify that there is a route to the remote host in the routing tables.

If ping hangs with no response, make sure that the IP address is really that of the remote machine. If the IP address appears to be correct, look in the logfile where the PPP driver and PPP daemon log information has been collected. By default, this file is /usr/adm/syslog. The following example logfile and the description below the example show the steps PPP uses to achieve host-to-host connectivity. You can view the logfile to see if these steps have been successful.

  1 Mar 14 09:40:40 pppd[396]: ppp_add_inf: 10.0.246.6 --> 10.0.246.7
  2 Mar 14 09:44:27 pppd[396]: accept on socket 6
  3 Mar 14 09:44:27 pppd[409]: dial process sent pppd m_type=18, m_pid=409,
  4 m_tty='/dev/tty1A'
  5 Mar 14 09:44:27 pppd[396]: pppd_sockread s=7
  6 Mar 14 09:44:27 pppd[396]: Connected to remote system: tty=/dev/tty1A,
  7 pid=409,addr=10.0.54.54
  8 Mar 14 09:44:27 pppd[396]: ppp_add_conn
  9 Mar 14 09:44:27 pppd[396]: Assigned link id for outgoing link (10.0.
 10 246.6->10.0.246.7) is 1

line 1

The PPP daemon (shown as ``pppd'' in the logfile) builds the PPP network interface for the link.

UUCP connection made

Not shown in this logfile is pppd's contacting of the UUCP facility to request a UUCP connection. This information is logged at the local host console.

If the modem does not connect, check the /etc/ppphosts file to verify that the uucp parameter has the correct value for the remote host and that the value has an entry in the /usr/lib/uucp/Systems file. Verify that the entries in the /usr/lib/uucp/Devices and /usr/lib/uucp/Dialers files are correct for supporting the Systems file entry.

If the modem does connect but then disconnects, you can also use the UUCP error codes and PPP debugging information to troubleshoot this problem. For example, if the UUCP error code says something like chat script failed, you can view the chat script dialogue between the local and remote hosts at the console.

If you find that the modem connects but then disconnects after a short time, the problem probably lies with the PPP link parameter negotiation. To debug this type of problem, see ``Troubleshooting PPP negotiation''.

lines 3,4

If the UUCP facility successfully connects with the remote host, pppd receives this information along with the tty of the connection.

lines 6,7

pppd links the tty of that connection under the PPP driver.

lines 9-10

The PPP daemon assigns an ID number (1) to the outgoing link.

With knowledge of either the local or remote IP address for the PPP link you are troubleshooting, you can search on either one in the /usr/adm/syslog file to see if the above activities completed successfully. Success is achieved if pppd assigned a link ID.

If ping is successful when using the IP address of the remote host, you may wish to test whether one can reach the remote host using the host names by which it should be reachable. See ``Using ping to test reachability using host names'' for the command, possible error message, and resolutions.

Next topic: Testing manual dialup connectivity
Previous topic: Verifying UUCP connectivity before PPP use

© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003