Dell PowerSwitch S4820T 9.50.1 Configuration Guide for the S4820T System - Page 1076

FREE MEMORY uvmexp.free = 0x2312 Enabling TCP Dumps A TCP dump captures CPU-bound control plane traffic to improve troubleshooting and system manageability. When you enable TCP dump, it captures all the packets on the local CPU, as specified in the CLI. You can save the traffic capture files to flash, FTP, SCP, or TFTP. The files saved on the flash are located in the flash://TCP_DUMP_DIR/Tcpdump_/ directory and labeled tcpdump_*.pcap. There can be up to 20 Tcpdump_ directories. The 21st file overwrites the oldest saved file. The maximum file size for a TCP dump capture is 1MB. When a file reaches 1MB, a new file is created, up to the specified total number of files. Maximize the number of packets recorded in a file by specifying the snap-length to capture the file headers only. The tcpdump command has a finite run process. When you enable the tcpdump command, it runs until the capture-duration timer and/or the packet-count counter threshold is met. If you do not set a threshold, the system uses a default of a 5 minute capture-duration and/or a single 1k file as the stopping point for the dump. You can use the capture-duration timer and the packet-count counter at the same time. The TCP dump stops when the first of the thresholds is met. That means that even if the duration timer is 9000 seconds, if the maximum file count parameter is met first, the dumps stop. To enable a TCP dump, use the following command. • Enable a TCP dump for CPU bound traffic. CONFIGURATION mode tcpdump cp [capture-duration time | filter expression | max-file-count value | packet-count value | snap-length value | write-to path] 1076 S-Series Debugging and Diagnostics