DISPLAY EE

You can use the DISPLAY EE command to obtain information about Enterprise Extender. This command has various formats providing general Enterprise Extender information as well as detailed connection throughput statistics. A few of the display command formats will be shown along with some of the important messages.
  • To display general Enterprise Extender information in summary format, use the following command: 
    D NET,EE
    • Message IST1685I identifies the job name of the TCP/IP stack which Enterprise Extender is using.
    • Message IST2004I displays the Enterprise Extender Logical Data Link Control (LDLC) timer and disconnect timer values associated with the PORT definition statement.
    • Message IST2005I shows the number of seconds VTAM® waits for name-to-address resolution requests to complete before canceling the request. The value displayed is associated with the Enterprise Extender port and affects only local HOSTNAME name-to-address resolution requests. When an EE line is in the process of being activated, and VTAM is performing name-to-address resolution for the local HOSTNAME, a display of the line (D NET,ID=linename) will show a state of PGAIN (Pending GetAddrInfo). If an EE line is hung in PGAIN state, you can perform the following steps to identify why the local HOSTNAME name-to-address resolution is not completing:
      1. Verify that the TCP/IP stack identified in message IST1685I is active.
      2. Verify that the TCP/IP resolver is active.

      Result: If IPRESOLV displays the value of 0, VTAM will wait infinitely for the name-to-address resolution to complete. In this situation, VTAM relies on the TCP/IP resolver to time out the resolution. For more information, see z/OS Communications Server: IP Configuration Guide.

    • IST2008I displays the IP Type of Service (ToS) values associated with each of the Enterprise Extender port priorities.
    • IST2021I displays the total number of active Enterprise Extender connections.
  • To display general Enterprise Extender information in detail, use the following command: 
    D NET,EE,DET
    • The detailed format of the general Enterprise Extender display provides detailed information for each local IP address. Message IST1680I is the first message of a message group. The information for each local IP address is displayed between the IST924I messages.
      For each local IP address active to Enterprise Extender, the following information is displayed:
      • Message IST2004I displays the Enterprise Extender Logical Data Link Control (LDLC) timer and disconnect timer values used by this local static VIPA.
      • Message IST1910I/IST1911I displays the local HostName (if applicable).
      • Message IST2009I displays the total number of RTP pipes traversing EE connections associated with this local IP address. This message also displays the total number of LU-LU sessions associated with these RTP pipes.
      • IST2010I displays the number of Enterprise Extender lines which have been INOPed because of SRQRETRY exhaustion. This count is maintained from the time the first EE line (associated with this specific local IP address) is activated, until the last line (associated with this specific local IP address) is deactivated. When the last line is deactivated for this local IP address, this counter will be cleared.
      • For each VRN, the following information will be displayed:
        • Message IST1324I displays the VNNAME and VNGROUP, along with a LOCAL or GLOBAL VRN indicator.
        • Message IST2011I displays the number of available lines associated with this VRN.

          Guideline: Verify that IST2011I displays enough lines to support the number of VRN connections that can exist. If the number of available lines drops to zero, new EE connections associated with this connection network will fail to connect.

        • IST2012I displays the number of active EE connections associated with this VRN.
      • Message IST2013I displays the number of available lines for predefined EE connections associated with this local IP address.

        Guideline: Verify that IST2013I displays enough lines to support the number of predefined connections that can exist for this local IP address. If the number of lines is not large enough, new EE connections will fail to connect. If the number of available lines displays as zero, this might mean that all Enterprise Extender lines are associated with the Connection Network (CN) groups. For this case, all available lines that are associated with CN groups are available for predefined connections as well. Lines will be selected from the local CN groups first. If no local CN lines are available, then lines will be selected from the global CN groups.

  • To display Enterprise Extender connection information in detail, use the following command: 
    D NET,EE,ID=puname or linename,DET

    Tip: The DISPLAY EE commands have various formats in which the connection information can be displayed. The example here uses the ID=operand. The DISPLAY EE command with the HOSTNAME/IPADDR operands provides essentially the same information.

    • Message IST2022I displays the date and time of the Enterprise Extender connection activation.
    • Message IST2114I displays the initial, maximum, and current LIVTIME values for an EE connection.
    • Message IST2025I displays the number of LDLC signals over this EE connection which did not receive a response on the first try. The signal required at least one retransmission before a response was received from the EE partner.
    • Message IST2026I is closely associated with message IST2025I. The value displayed here indicates the number of LDLC signals over this EE connection which did not receive a response up to SRQRETRY times. It required the signal to be retransmitted SRQRETRY times, at which time a response was received from the EE partner.

      Tip: If this display is issued repeatedly over a period of time, and the values displayed in messages IST2025I or IST2026I continue to grow, this indicates that there is most likely a problem in the network. Network congestion is a possible problem which might lead to Enterprise Extender failure. Increasing the LIVTIME, SRQRETRY, and SRQTIME values on the EE XCA PORT macro will allow Enterprise Extender connections to tolerate longer network delays. However, if severe network delays are encountered, it is most likely Enterprise Extender connections will INOP due to timeout conditions.

    • Message IST2029I displays the largest MTU size that Enterprise Extender will send over the IP network for this connection. When policy-based routing is in effect, the MTU size might be different for each of the ports, depending on the routes chosen for EE traffic. This message is issued for each of the five EE ports regardless of whether policy-based routing is in effect and regardless of whether the display is for an IPv4 or IPv6 connection. The MTU size (both IPv4 and IPv6) might change during the life of the EE connection. The displayed value is obtained in the following manner: Message IST2029I displays the largest MTU size that Enterprise Extender will send over the IP network for this connection. When policy-based routing is in effect, the MTU size might be different for each of the ports, depending on the routes chosen for EE traffic. This message is issued for each of the five EE ports regardless of whether policy-based routing is in effect and regardless of whether the display is for an IPv4 or IPv6 connection. The MTU size (both IPv4 and IPv6) might change during the life of the EE connection. The displayed value is obtained in the following manner:
      • Initially, VTAM queries the TCP/IP stack for its MTU size and sets the EE connection to use this value. This MTU size has already been reduced to account for various header lengths such as the IP, UDP, and LLC headers necessary for EE traffic.
      • VTAM also takes into account the VTAM MTU operand value, if specified. The MTU operand may be specified on three types of VTAM major nodes:
        • For EE connection networks, this parameter may be defined on the connection network GROUP definition statements in the EE XCA major node.
        • For dial-in Enterprise Extender connections which have their associated PUs dynamically created, this parameter may be defined on the model major node (DYNTYPE=EE) PU definition statement.
        • For predefined Enterprise Extender connections, this parameter may be defined on the PU definition statement in the switched major node.
      • VTAM then takes the lesser of the TCP/IP stack's computed MTU size and the VTAM defined MTU operand value (if specified). If the TCP/IP stack presents a value less than 768 bytes, VTAM sets the MTU to 768 because this is the smallest packet size allowed by the HPR architecture.
      • Generally the MTU size for an EE connection is fairly constant when the EE connection is established. However, in the event the TCP/IP stack's MTU size changes, RTP pipes with endpoints on the same node as the TCP/IP stack dynamically detect these changes when their outbound packets are being transmitted. The MTU size changes because of the following reasons:
        • New IP routes come available with different local MTU sizes
        • Existing IP routes become unavailable.
        • Path MTU discovery is enabled for IPv4 or IPv6 EE connections (See the PMTUD start option for details, z/OS Communications Server: SNA Resource Definition Reference), and path MTU changes are discovered in the IP network.
    • Message IST2038I and IST2039I display the number of packets and the number of bytes that have been retransmitted. These counts are displayed for each port priority level. If the values displayed in these two messages increase over time, this indicates problems within the transport network. Large numbers of retransmissions due to network congestions will result in poor RTP performance. If excessive retransmissions occur, RTP path switching might occur.