Modifying options with VARY

After starting a packet trace, you can change the trace using the VARY command. For example, if you want to change the packet trace to abbreviate the data being traced, use the following command:

V TCPIP,tcpproc,PKT,ABBREV

You can display the results of the VARY command using the Netstat command:

NETSTAT -p TCPCS -d                                                   
MVS TCP/IP NETSTAT CS V1R10 TCPIP Name: TCPCS 18:03:31
DevName: LOOPBACK          DevType: LOOPBACK
  DevStatus: Ready
  LnkName: LOOPBACK          LnkType: LOOPBACK   LnkStatus: Ready
    NetNum:  0   QueSize: 0
    BytesIn: 813                     BytesOut: 813
    ActMtu:  65535
  BSD Routing Parameters:
    MTU Size: 00000             Metric: 00
    DestAddr: 0.0.0.0           SubnetMask: 0.0.0.0
  Packet Trace Setting:
    Protocol: *                 TrRecCnt: 00000000  PckLength: 00200
    Discard:  0
    SrcPort:  *                 DestPort: *         PortNum: *
    IpAddr:   *                 SubNet:   *
  Multicast Specific:
    Multicast Capability: No

Tip: If you are a TSO user, use the corresponding NETSTAT option.

By issuing multiple VARY commands, you can OR filters together. For example, issuing the following VARY commands records all packets whose destination port is xxxx or whose source port is xxxx.

V TCPIP,tcpproc,PKTTRACE,DEST=xxxx 
V TCPIP,tcpproc,PKTTRACE,SRCP=xxxx

The result is a trace that contains only packets with a source port of xxxx or packets with a destination port of xxxx.

Tip: An alternative command to use is the PKTTRACE command with PORTNUM.

V TCPIP,,PKTTRACE,PORTNUM=xxxx

If both DEST and SRCP are specified in the same command, you can AND the parameters together. For example, issuing the following VARY command records only the packets with both a destination port of xxxx and a source port of yyyy.

V TCPIP,tcpproc,PKTTRACE,DEST=xxxx,SRCP=yyyy

You can use the VARY TCPIP,tcpproc,OBEYFILE command to make temporary dynamic changes to system operation and network configuration without stopping and restarting the TCP/IP address space. For example, if you started the address space TCPIPA and created a sequential data set USER99.TCPIP.OBEYFIL1 containing packet trace statements, issue the following command:

VARY TCPIP,TCPIPA,CMD=OBEYFILE,DSN=USER99.TCPIP.OBEYFIL1

The VARY TCPIP,PKTTRACE command is cumulative. You can trace all packets for specified IP addresses by entering multiple PKTTRACE commands. In the following example, the two commands trace all the packets received and all the packets sent for the specified IP addresses.

VARY TCPIP,,PKT,ON,IPADDR=10.27.142.44
VARY TCPIP,,PKT,ON,IPADDR=10.27.142.45