3Com Router 3031, Command Reference Manual

Page: 31 / 838

Information Processing Commands 31
The tracert command is executed following this procedure: The system first sends
a packet with TTL as 1 and the first hop returns an ICMP error message indicating
that the packet cannot be transmitted due to TTL timeout. and then the system
transmits the packet again with TTL being set to 2 and the second hop returns TTL
timeout message similarly. This process continues until the packet reaches its
destination. The purpose of such a process is to record the source addresses where
these ICMP TTL timeout messages are sent so as to outline the path along which
the IP packet can reach the destination.
When a network fault is detected by using the ping command, tracert can be used
to locate the failure on the network.
The output information of the command tracert includes IP addresses of all the
GWs along the path to the destination. If some GW times out, “***” will be
output.
Example
<3Com> tracert 18.26.0.115
tracert to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms
2 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 19 ms 19 ms
3 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 19 ms 19 ms
4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 19 ms 39 ms 39 ms
5 ccn-nerif22.Berkeley.EDU (128.32.168.22) 20 ms 39 ms 39 ms
6 128.32.197.4 (128.32.197.4) 59 ms 119 ms 39 ms
7 131.119.2.5 (131.119.2.5) 59 ms 59 ms 39 ms
8 129.140.70.13 (129.140.70.13) 80 ms 79 ms 99 ms
9 129.140.71.6 (129.140.71.6) 139 ms 139 ms 159 ms
10 129.140.81.7 (129.140.81.7) 199 ms 180 ms 300 ms
11 129.140.72.17 (129.140.72.17) 300 ms 239 ms 239 ms
12 * * *
13 128.121.54.72 (128.121.54.72) 259 ms 499 ms 279 ms
14 * * *
15 * * *
16 * * *
17 * * *
18 ALLSPICE.LCS.MIT.EDU (18.26.0.115) 339 ms 279 ms 279 ms
Information
Processing Commands
display
channel Syntax
display channel [ channel-number | channel-name ]
View
Any view.
Parameter
channel-number: Channel number, ranging 0 to 9. That is, the system
has 10 channels.
channel-name: Channel name.