Nokia IPSO 4.0 manual Tracing, Troubleshooting Cause Codes, To trace Isdn traffic using tcpdump

2

The most recent system log messages appear.

Tracing

You can use the tcpdump utility to trace ISDN D-channel traffic (Q.921 and Q.931 protocols) and B-channel traffic (PPP/multilink PPP and TCP/IP protocols).

When running tcpdump on an ISDN interface, if no options are given on the command line, the following messages are decoded and displayed:

„Q.931 messages

„PPP messages and the fields inside them

„Any IP traffic on the B-channels

If -e option is specified on the command line, in addition to the preceding messages, all Q.921 messages are also decoded and displayed.

If the -v option is used, Q.931 messages are displayed. Also the fields in all PPP messages and their values are displayed in an extended format.

To trace ISDN traffic using tcpdump

1.Create a telnet session and log in to the firewall.

2.Enter tcpdump -i <isdn-interface>

Troubleshooting Cause Codes

Use the following debug commands to display the ISDN cause code fields in the following table: i=0xy1y2z1z2a1a2

Table 5 ISDN Cause Code Fields

Cause Code	Description
y1	8	- ITU-T standard coding
y2	0	- User
	1	- Private network serving local user
	2	- Public network serving local user
	3	- Transit network
	4	- Public network serving remote user
	5	- Private network serving remote user
	7	- International network

A - Network beyond Internetworking point

66 Nokia Network Voyager for IPSO 4.0 Reference Guide