3Com 3C13636 Configuration Manual page 510

3Com Router 3000 Ethernet Family
Configuration Guide
Troubleshooting: In the event of such a fault, you can enable the corresponding
debugging information output to view the debugging information.
Use the command debugging udp to enable the UDP debugging information
output to trace the UDP packet. When the router sends or receives UDP packets,
the content format of the datagram can be displayed in real time. You can locate
the problem from the contents of the datagram.
The following are the UDP packet formats:
*0.348541898-SOCKET-8-UDPINI:UDP packet information :
Incoming UDP datagram:
source IP address:
source port:
destination IP address:
destination port:
The length of UDP packet:
Use the command debugging tcp packet to enable the TCP debugging
information output to trace the TCP packets. Two TCP packet formats are
available for selection. One is to debug and trace the receiving and sending of all
the TCP packets of the TCP connection that take this device as one end. The
operations are as follows:
[3Com] info-center enable
[3Com] quit
<3Com> debugging tcp packet
Then the TCP packets received or sent can be checked in real time. Specific packet
formats are as follows:
*0.348623498-SOCKET-8-OUTBAND:TCP packet information :
TCP output packet:
source IP address:
source port:
destination IP address:
destination port:
packet sequence number:
ACK sequence number:
The packet flags:
The total length of IP packet:
The length of TCP header:
The other is to debug and trace the packets with SYN, FIN or RST flags being set.
Operations are as follows:
[3Com] info-center enable
[3Com] quit
<3Com> debugging tcp event
172.16.101.70
138
172.16.255.255
138
209
172.16.201.1
23
172.16.105.148
1031
4818317
3644122
ACK PUSH
436
20
3Com Corporation
10-9
Chapter 10 IP Performance Configuration