3Com 4210G Series - System Debugging; Introduction to System Debugging

21-5
To do… Use the command… Remarks
Enable sending of
ICMP timeout
packets
ip ttl-expires enable
Required
Disabled by default.
Enable sending of
ICMP destination
unreachable packets
ip unreachables enable
Required
Disabled by default.
tracert [ -a source-ip | -f first-ttl | -m max-ttl |
-p port | -q packet-number | -vpn-instance
vpn-instance-name | -w timeout ] * host
Display the routes
from source to
destination
tracert ipv6 [ -f first-ttl | -m max-ttl | -p port |
-q packet-number | -w timeout ] * host
Required
Use either approach
The tracert command is
applicable in an IPv4
network; the tracert ipv6
command is applicable in an
IPv6 network.
Available in any view
System Debugging
Introduction to System Debugging
The device provides various debugging functions. For the majority of protocols and features supported,
the system provides corresponding debugging information to help users diagnose errors.
The following two switches control the display of debugging information:
z Protocol debugging switch, which controls protocol-specific debugging information.
z Screen output switch, which controls whether to display the debugging information on a certain
screen.
As
Figure 21-3 illustrates, suppose the device can provide debugging for the three modules 1, 2, and 3.
Only when both the protocol debugging switch and the screen output switch are turned on can
debugging information be output on a terminal.
Figure 21-3 The relationship between the protocol and screen debugging switch
Debugging
information
Protocol
debugging
switch
switch
Screen output
OFF
ON
OFF
ON
1
3
1 2 3
OFF
ON
ON
1
3
1 2 3
1
3
ON
Debugging
information
switch
Screen output
Protocol
switch
debugging