Chapter 35

Fixing Common Problems (Tasks)

This chapter contains information for diagnosing and troubleshooting common problems that occur with Solaris PPP 4.0. The following topics are covered:

The sources PPP Design, Implementation, and Debugging by James Carlson and the Australian National University's web site also have detailed advice for PPP troubleshooting. For more information, see "Professional Reference Books About PPP" and "Web Sites About PPP".

Solving PPP Problems (Task Map)

Use the following task map to quickly access advice and solutions for common PPP problems.

Table 35-1 Task Map for Troubleshooting PPP

Task	Definition	For Instructions
Obtain diagnostic information about the PPP link	Use PPP diagnostic tools to get output for troubleshooting	"How to Obtain Diagnostic Information From pppd"
Obtain debugging information for the PPP link	Use the `pppd debug` command to generate output for troubleshooting	"How to Turn on PPP Debugging"
Troubleshoot general problems with the network layer	Identify and fix PPP problems that are network-related by using a series of checks	"How to Diagnose Network Problems"
Troubleshoot general communications problems	Identify and fix communications problems that affect the PPP link	"How to Diagnose and Fix Communications Problems"
Troubleshoot configuration problems	Identify and fix problems in the PPP configuration files	"How to Diagnose Problems With the PPP Configuration"
Troubleshoot modem-related problems	Identify and fix modem problems	"How to Diagnose Modem Problems"
Troubleshoot chat script-related problems	Identify and fix chat script problems on a dial-out machine	"How to Obtain Debugging Information for Chat Scripts"
Troubleshoot serial line speed problems	Identify and fix line speed problems on a dial-in server	"How to Diagnose and Fix Serial Line Speed Problems"
Troubleshoot common problems for leased lines	Identify and fix performance problems on a leased line	"Fixing Leased-Line Problems"
Troubleshoot problems related to authentication	Identify and fix problems related to the authentication databases	"Diagnosing and Fixing Authentication Problems"
Troubleshoot problem areas for PPPoE	Use PPP diagnostic tools to obtain output for identifying and fixing PPPoE problems	"How to Obtain Diagnostic Information for PPPoE"

Tools for Troubleshooting PPP

PPP links generally have three major areas of failure:

Failure of the link to be established
Poor performance of the link as it is used
Problems that can be traced to the networks on either side of the link

The easiest way to find out if PPP works is to run a command, such as ping or traceroute, to a host on the peer's network, and observe the results. However, to monitor performance of a link that has been established or to troubleshoot a problematic link, you need to use PPP and UNIX debugging tools.

This section explains how to obtain diagnostic information from pppd and its associated log files. The remaining sections in this chapter describe common problems with PPP that you can discover and fix with the aid of the PPP troubleshooting tools.

How to Obtain Diagnostic Information From pppd

The next procedure shows how to view the current operation of a link on the local machine.

Become superuser on the local machine.

Run pppd with the serial device configured for PPP as the argument:

# pppd /dev/ttyname debug updetach
The next examples show the resulting displays for a dial-up link and a leased-line link when pppd runs in the foreground. If you run pppd debug in the background, the output produced is sent to the /etc/ppp/connect-errors file.

Example 35-1 Output From a Properly Operating Dial-up Link

# pppd /dev/cua/b debug updetach
have route to 0.0.0.0/0.0.0.0 via 172.21.0.4
serial speed set to 230400 bps
Using interface sppp0
Connect: sppp0 <--> /dev/cua/b
sent [LCP ConfReq id=0x7b <asyncmap 0x0> <magic 0x73e981c8> <pcomp> <accomp>]
rcvd [LCP Ident id=0x79 magic=0x0 "ppp-2.4.0b1 (Sun Microsystems, Inc., Dec  6 
	2000 09:36:22)"]
Peer Identification: ppp-2.4.0b1 (Sun Microsystems, Inc., Dec  6 2000 09:36:22)
	rcvd [LCP ConfRej id=0x7b <asyncmap 0x0>]
sent [LCP Ident id=0x7c magic=0x0 "ppp-2.4.0b1 (Sun Microsystems, Inc., Nov 15 
	2000 09:38:33)"
sent [LCP ConfReq id=0x7d <magic 0x73e981c8> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x7d <magic 0x73e981c8> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x78 <magic 0xdd4ad820> <pcomp> <accomp>]
sent [LCP ConfAck id=0x78 <magic 0xdd4ad820> <pcomp> <accomp>]
sent [LCP Ident id=0x7e magic=0x73e981c8 "ppp-2.4.0b1 (Sun Microsystems, Inc., 
	Nov 15 2000 09:38:33)"]
sent [IPCP ConfReq id=0x3d <addr 0.0.0.0> <compress VJ 0f 01>]
rcvd [LCP Ident id=0x7a magic=0xdd4ad820 "ppp-2.4.0b1 (Sun Microsystems, Inc., 
	Dec  6 2000 09:36:22)"]
Peer Identification: ppp-2.4.0b1 (Sun Microsystems, Inc., Dec  6 2000 09:36:22)
rcvd [IPCP ConfReq id=0x92 <addr 10.0.0.1> <compress VJ 0f 01>
sent [IPCP ConfAck id=0x92 <addr 10.0.0.1> <compress VJ 0f 01>
rcvd [IPCP ConfNak id=0x3d <addr 10.0.0.2>]]
sent [IPCP ConfReq id=0x3e <addr 10.0.0.2> <compress VJ 0f 01>]
rcvd [IPCP ConfAck id=0x3e <addr 10.0.0.2> <compress VJ 0f 01>]
local  IP address 10.0.0.2
remote IP address 10.0.0.1

Example 35-2 Output From a Properly Operating Leased-Line Link

# pppd /dev/se_hdlc1 default-asyncmap debug updetach
pppd 2.4.0b1 (Sun Microsystems, Inc., Oct 24 2001 07:13:18) started by root, uid 0
synchronous speed appears to be 0 bps
init option: '/etc/ppp/peers/syncinit.sh' started (pid 105122)
Serial port initialized.
synchronous speed appears to be 64000 bps
Using interface sppp0
Connect: sppp0 <--> /dev/se_hdlc1
sent [LCP ConfReq id=0xe9 <magic 0x474283c6><pcomp> <accomp>]
rcvd [LCP ConfAck id=0xe9 <magic 0x474283c6><pcomp> <accomp>]
rcvd [LCP ConfReq id=0x22 <magic 0x8e3a53ff><pcomp> <accomp>]
sent [LCP ConfReq id=0x22 <magic 0x8e3a53ff><pcomp> <accomp>]
sent [LCP Ident id=0xea magic=0x474283c6 "ppp-2.4.0b1 (Sun Microsystems, Inc., Oct 
	22 2001 14:31:44)"]
sent [IPCP ConfReq id=0xf7 <addr 0.0.0.0> <compress VJ Of o1>]]
sent [CCP ConfReq id=0x3f <deflate 15> <deflate(old#) 15> <bsd v1 15>]
rcvd [LCP Ident id=0x23 magic=0x8e3a53ff "ppp-2.4.0b1 (Sun Microsystems, Inc., Oct 
	22 2001 14:31:44)"]
Peer Identification: ppp-2.4.0b1 (Sun Microsystems, Inc., Oct 22 2001 14:31:44)
rcvd [IPCP ConfReq id=0x25 <addr 10.0.0.1> <compress VJ Of 01>]
sent [IPCP ConfAck id=0x25 <addr 10.0.0.1> <compress VJ Of 01>]
rcvd [CCP ConfReq id=0x3 <deflate 15> <deflate(old#) 15 <bsd v1 15>]
sent [CCP ConfAck id=0x3 <deflate 15> <deflate(old#) 15 <bsd v1 15>]
rcvd [IPCP ConfNak id=0xf8 <addr 10.0.0.2>]
rcvd [IPCP ConfReq id=0xf7 <addr 10.0.0.2> <compress VJ Of 01>]
rcvd [CCP ConfAck id=0x3f <deflate 15> <deflate(old#) 15 <bsd v1 15>]
Deflate (15) compression enabled
rcvd [IPCP ConfAck id=0xf8 <addr 10.0.0.2> <compress VJ Of 01>]
local  IP address 10.0.0.2
remote IP address 10.0.0.1