ZyXEL Communications ISG50 User Manual

Chapter 56 Diagnostics

ISG50 User’s Guide

Host Port

This field is configurable when you set the IP Type to any, tcp, or udp. 
Specify the port number of traffic to capture.

Continuously capture 
and overwrite old ones

Select this to have the ISG50 keep capturing traffic and overwriting old 
packet capture entries when the available storage space runs out.

Save data to onboard 
storage only 

Select this to have the ISG50 only store packet capture entries on the 
ISG50.

Save data to USB 
storage 

Select this to have the ISG50 store packet capture entries only on a USB 
storage device connected to the ISG50.

Status:

Unused - the connected USB storage device was manually unmounted by 
using the Remove Now button or for some reason the ISG50 cannot 
mount it.

none -  no USB storage device is connected.

available - you can have the ISG50 use the USB storage device. The 
available storage capacity also displays.

Note: The ISG50 reserves some USB storage space as a buffer.

Captured Packet Files

When saving packet captures only to the ISG50’s onboard storage, specify 
a maximum limit in megabytes for the total combined size of all the 
capture files on the ISG50. 

When saving packet captures to a connected USB storage device, specify a 
maximum limit in megabytes for each capture file. 

Note: If you have existing capture files and have not selected the 

Continuously capture and overwrite old ones option, you may 
need to set this size larger or delete existing capture files.

The valid range is 1 to 10000. The ISG50 stops the capture and generates 
the capture file when either the file reaches this size or the time period 
specified in the Duration field expires.

Split threshold

Specify a maximum size limit in megabytes for individual packet  capture 
files. After a packet capture file reaches this size, the ISG50 starts another 
packet capture file.

Duration

Set a time limit in seconds for the capture. The ISG50 stops the capture 
and generates the capture file when either this period of time has passed 
or the file reaches the size specified in the File Size field. 0 means there is 
no time limit.

File Suffix

Specify text to add to the end of the file name (before the dot and filename 
extension) to help you identify the packet capture files. Modifying the file 
suffix also avoids making new capture files that overwrite existing files of 
the same name. 

The file name format is “interface name-file suffix.cap”, for example 
“vlan2-packet-capture.cap”.

Number Of Bytes To 
Capture (Per Packet)

Specify the maximum number of bytes to capture per packet. The ISG50 
automatically truncates packets that exceed this size. As a result, when 
you view the packet capture files in a packet analyzer, the actual size of the 
packets may be larger than the size of captured packets.

Maintenance > Diagnostics > Packet Capture (continued)