I am running z/OS Comm Server, what commands can I use to diagnose network connectivity problems?

Below is a basic list of tools for diagnosing network connectivity problems. See the z/OS Comm Server IP Diagnosis manual for more detailed information:

1) PING command The packet Internet groper (Ping) command sends an Internet Control Message Protocol (ICMP/ICMPv6) Echo Request to a host, gateway, or router with the expectation of receiving a reply. You can invoke the Ping function by using the TSO PING command or the z/OS UNIX shell ping or oping command.

For a complete description of the Ping command and examples of Ping output, refer to the z/OS Communications Server: IP System Administrator's Commands.

2) TCP/IP NETSTAT command

You can use the Netstat command to verify your TCP/IP configuration. The information provided in the output from the Netstat command should be checked against the values in your configuration data sets for the TCP/IP stack. Refer to the PROFILE DD statement in the TCP/IP started task procedure for the name of the configuration data sets.

Netstat can be invoked by using the TSO NETSTAT command, the z/OS UNIX shell netstat/onetstat command, or the console DISPLAY TCPIP,,NETSTAT command.

The following Netstat commands can be used to verify the state of those network resources that affect connectivity:

 Netstat HOME/-h, 

 Netstat DEVLINKS/-d, 

 Netstat ROUTE/-r, 

 Netstat ARP/-R, 

 Netstat ND/-n, 

For a complete description of the Netstat command and examples of Netstat output, refer to the z/OS Communications Server: IP System Administrator's Commands.

3) DISPLAY TCPIP,,OSAINFO command You can use the DISPLAY TCPIP,,OSAINFO command to retrieve information for an active IPAQENET/IPAQENET6 interface or link directly from an OSA-Express feature. The report includes information about the OSA-Express feature and about the interface or link. Registered unicast and multicast addresses are displayed as are routing variables for QDIO inbound workload queueing. Some of these values can be compared to the Netstat DEvlinks/-d report to ensure z/OS Communications Server and the OSA-Express are using the same information.

For a complete description of the command and examples of the command output, refer to DISPLAY TCPIP,,OSAINFO in z/OS Communications Server: IP System Administrator's Commands.

4) TCP/IP Traceroute command:

Traceroute displays the route that a packet takes to reach the requested target. Traceroute starts at the first router and uses a series of UDP probe packets with increasing IP time-to-live (TTL) or hop count values to determine the sequence of routers that must be traversed to reach the target host. The Traceroute function can be invoked by either the TSO TRACERTE command or the z/OS UNIX shell traceroute/otracert command.

The packetSize option lets you increase the IP packet size to see how size affects the route that the Traceroute packet takes. It also shows the point of failure if a destination address cannot be reached.

For the complete syntax of the TSO TRACERTE and z/OS UNIX traceroute/otracert command and examples of command output, refer to the z/OS Communications Server: IP System Administrator's Commands.

5) SNMP remote Ping command :

Use the SNMP remote Ping command to determine the response time between two remote hosts. For example, from Host A, you can determine the response time (Ping) between Hosts B and C, assuming the SNMP agent and TCP/IP subagent are running on Host B. Refer to the z/OS Communications Server: IP System Administrator's Commands for details.