Report field descriptions

Most of the TCP/IP statistics for IP, ICMP, TCP, and UDP protocols are defined in the SNMP IP-MIB (RFC2011 - SNMPv2 Management Information Base for the Internet Protocol Using SMIv2), TCP-MIB (RFC 2012 - SNMPv2 Management Information Base for the Transmission Control Protocol Using SMIv2), and UDP-MIB (RFC 2013 - SNMPv2 Management Information Base for the User Datagram Protocol Using SMIv2) MIB modules. See these SNMP MIB modules for more detailed information.

  • The following describes the IPv4 and IPv6 statistics displayed:
    Packets Received
    The total number of input datagrams received from interfaces.
    Received Header Errors
    The number of input datagrams discarded due to errors in their IP headers.
    Received Address Errors
    The number of input datagrams discarded because the IP address in their IP header's destination field was not valid.
    Datagrams Forwarded
    The number of input datagrams forwarded to their final destination.
    Unknown Protocols Received
    The number of datagrams discarded because of an unknown or unsupported protocol.
    Received Packets Discarded
    The number of input datagrams that were discarded that are not accounted for in another input discard counter.
    Received Packets Delivered
    The total number of input datagrams successfully delivered to IP user-protocols.
    Output Requests
    The total number of IP datagrams that local IP user-protocols supplied to IP in requests for transmission.
    Output Discards No Route
    The number of IP datagrams discarded because no route could be found to transmit them to their destination.
    Output Discards (Other)
    The number of output datagrams generated by this stack that could not be transmitted.
    Reassembly Timeouts
    The number of packets that were being held for reassembly but which were discarded due to the fact that the remaining fragments were not received within reassembly timeout.
    Reassembly Required
    The number of IP fragments received that needed to be reassembled.
    Reassembly Successful
    The number of IP datagrams successfully reassembled.
    Reassembly Failures
    The number of failures detected by the IP reassembly algorithm.
    Datagrams Successfully Fragmented
    The number of IP datagrams that have been successfully fragmented.
    Datagrams Failing Fragmentation
    The number of IP datagrams that have been discarded because they needed to be fragmented but could not be.
    Fragments Created
    The number of IP datagram fragments that have been generated as a result of fragmentation.
    Inbound Packets handled by zIIP
    The number of inbound packets that were processed by a zIIP. This counter applies only to IPSec workloads, whose CPU cycles are being displaced to a zIIP. The Packets Received counter includes the packets that are received on zIIP, so the percentage of total inbound packets that were processed by zIIP can be calculated as (Inbound Packets handled by zIIP ÷ Packets Received) × 100. Similarly, the number of inbound packets that were processed by General Purpose Processors is equal to (Packets Received - Inbound Packets handled by zIIP).
    Outbound Packets handled by zIIP
    The number of outbound packets that were processed by a zIIP. This counter applies only to IPSec workloads, whose CPU cycles are being displaced to a zIIP. The Output Requests counter includes the outbound packets processed on zIIP, so the percentage of total outbound packets that were processed by zIIP can be calculated as (Outbound Packets handled by zIIP ÷ Output Requests) × 100. Similarly, the number of outbound packets that were processed by General Purpose Processors is equal to (Output Requests - Outbound Packets handled by zIIP).
  • The following describes the IP general statistics displayed. The statistic values for these counters reflect both IPv4 and IPv6 processing combined.
    Inbound Calls from Device Layer
    The number of times the inbound TCP/IP Data Path has received control from the Device Layer.
    Inbound Frame Unpacking Errors
    The number of times a received frame could not be unpacked into its constituent datagrams.
    Inbound Discards Memory Shortage
    The number of inbound packets discarded due to a CSM storage shortage condition.
    Output Discards DLC Sync Errors
    The number of outbound packets discarded due to a synchronous error in the Data Link Control.
    Output Discards DLC Async Errors
    The number of outbound packets discarded due to an asynchronous error in the Data Link Control.
    Output Discards Memory Shortage
    The number of outbound packets discarded due to a CSM storage shortage condition.
  • The following describes the ICMP statistics displayed:
    Messages
    The total number of ICMP messages received and sent.
    Errors
    The number of ICMP messages received and sent but determined as having ICMP-specific errors.
    Destination Unreachable
    The number of ICMP Destination Unreachable messages received and sent.
    Time Exceeded
    The number of ICMP Time Exceeded messages received and sent.
    Parameter Problems
    The number of ICMP Parameter Problem messages received and sent.
    Source Quenchs
    The number of ICMP Source Quench messages received and sent.
    Redirects
    The number of ICMP Redirect messages received and sent.
    Echos
    The number of ICMP Echo (request) messages received and sent.
    Echo Replies
    The number of ICMP Echo Reply messages received and sent.
    Timestamps
    The number of ICMP Timestamp (request) messages received and sent.
    Timestamp Replies
    The number of ICMP Timestamp Reply messages received and sent.
    Address Masks
    The number of ICMP Address Mask (request) messages received and sent.
    Address Mask Replies
    The number of ICMP Address Mask Reply messages received and sent.
  • The following describes the ICMPv6 statistics displayed:
    Messages
    The total number of ICMPv6 messages received and sent.
    Errors
    The number of ICMPv6 messages received and sent but determined as having ICMPv6-specific errors.
    Destination Unreachable
    The number of ICMPv6 Destination Unreachable messages received and sent.
    Time Exceeded
    The number of ICMPv6 Time Exceeded messages received and sent.
    Parameter Problems
    The number of ICMPv6 Parameter Problem messages received and sent.
    Redirects
    The number of ICMPv6 Redirect messages received and sent.
    Echos
    The number of ICMPv6 Echo messages received and sent.
    Echo Replies
    The number of ICMPv6 Echo Reply messages received and sent.
    Administratively Prohibited
    The number of ICMPv6 Administratively Prohibited messages received and sent.
    Packet Too Big
    The number of ICMPv6 Packet Too Big messages received and sent.
    Router Solicitations
    The number of ICMPv6 Router Solicitation messages received and sent.
    Router Advertisements
    The number of ICMPv6 Router Advertisement messages received and sent.
    Neighbor Solicitations
    The number of ICMPv6 Neighbor Solicitation messages received and sent.
    Neighbor Advertisements
    The number of ICMPv6 Neighbor Advertisement messages received and sent.
    Group Membership Queries
    The number of ICMPv6 Group Membership Queries received and sent.
    Group Membership Responses
    The number of ICMPv6 Group Membership Responses received and sent.
    Group Membership Reductions
    The number of ICMPv6 Group Membership Reductions received and sent.
  • The following describes the TCP statistics displayed:
    Current Established Connections
    The number of TCP connections for which the current state is either ESTABLISHED or CLOSE-WAIT.
    Guideline: This value, when displayed for TCP statistics, includes the number of TCP connections across SMC-R and SMC-D links. To determine the number of TCP connections that are not across SMC-R links, subtract the value for Current Established Connections displayed under SMCR Statistics from this value. To determine the number of TCP connections that are not across SMC-D links, subtract the value for Current Established Connections displayed under SMCD Statistics from this value.
    Current Stalled Connections
    The number of TCP connections whose send data flow is stalled. The send data flow is considered stalled if one or more of the following conditions are true:
    • The TCP send window size is less than 256 or is less than the smaller of the largest send window that has been seen for the connection and the default MTU. The TCP send window size is set based on values provided by the TCP peer. The default MTU for IPv4 is 576. The default MTU for IPv6 is 1280.
    • The TCP send queue is full and the data is not being retransmitted.
    Current Servers In Connection Flood
    The number of TCP servers under a potential connection flood attack. A server is considered under a potential connection flood attack when backlog queue expansion is required to handle the incoming connection requests. When more than 25 servers are under a potential connection flood attack, no server's backlog queue will be allowed to expand.
    Active Connections Opened
    The number of times TCP connections have made a direct transition to the SYN-SENT state from the CLOSED state.
    Guideline: This value, when displayed for TCP statistics, includes the number of TCP connections across SMC-R and SMC-D links that made a direct transition to the SYN-SENT state from the CLOSED state. To determine the number of these TCP connections that are not across SMC-R links, subtract the value for Active Connections Opened displayed under SMCR Statistics from this value. To determine the number of these TCP connections that are not across SMC-D links, subtract the value for Active Connections Opened displayed under SMCD Statistics from this value.
    Passive Connections Opened
    The number of times that TCP connections have made a direct transition to the SYN-RCVD state from the LISTEN state. This value, when displayed for TCP statistics, includes the number of TCP connections across SMC-R and SMC-D links that made a direct transition to the SYN-RCVD state from the LISTEN state. To determine the number of the TCP connections that are not across SMC-R links, subtract the value for Passive Connections Opened displayed under SMCR Statistics from this value. To determine the number of the TCP connections that are not across SMC-D links, subtract the value for Passive Connections Opened displayed under SMCD Statistics from this value.
    Connections Closed
    Number of TCP connections that have corresponding sockets closed.
    Guideline: This value, when displayed for TCP statistics, includes the number of TCP connections across SMC-R and SMC-D links that have corresponding sockets closed. To determine the number of these TCP connections that are not across SMC-R links, subtract the value for Connections Closed displayed under SMCR Statistics from this value. To determine the number of these TCP connections that are not across SMC-D links, subtract the value for Connections Closed displayed under SMCD Statistics from this value.
    Established Connections Dropped
    The number of times TCP connections made a direct transition to the CLOSED state from either the ESTABLISHED state or the CLOSE-WAIT state. This value includes the number of TCP connections across SMC-R links.
    Connection Attempts Dropped
    The number of times TCP connections have made a direct transition to the CLOSED state from either the SYN-SENT state or the SYN-RCVD state, plus the number of times TCP connections have made a direct transition to the listen state from the SYN-RCVD state.
    Connection Attempts Discarded
    Number of passive connection requests discarded.
    Timewait Connections Reused
    Number of TCP connections in the TIMEWAIT state that have been reused for connections in the SYN-RCVD state.
    Segments Received
    The total number of segments received.
    Guideline: This value, when displayed for TCP statistics, includes the number of Remote Direct Memory Access (RDMA) inbound operations that are processed across all SMC-R and SMC-D links. To determine the number of segments that are received on TCP connections that do not traverse SMC-R links, subtract the value for Segments Received displayed under SMCR Statistics from this value. To determine the number of segments that are received on TCP connections that do not traverse SMC-D links, subtract the value for Segments Received displayed under SMCD Statistics from this value.
    Note: This value is an ever increasing 32-bit counter that is subject to wrap during the duration the TCP/IP stack is active.
    Segments Received on OSA Bulk Queues
    The total number of segments received for all connections from the BulkData ancillary input queue (AIQ) of the inbound workload queuing function. For more information QDIO inbound workload queueing in z/OS Communications Server: IP Configuration Guide.
    Note: This value is an ever increasing 32-bit counter that is subject to wrap during the duration the TCP/IP stack is active.
    Header Prediction Ok for ACK
    Number of inbound TCP acknowledgments with successful header prediction.
    Header Prediction Ok for Data
    Number of inbound TCP data segments with successful header prediction.
    Duplicate ACKs
    Number of inbound duplicate TCP acknowledgments.
    Discards for Bad Checksum
    Number of inbound TCP segments discarded due to bad checksum.
    Discards for Bad Header Length
    Number of inbound TCP segments discarded due to bad header length.
    Discards for Data too Short
    Number of inbound TCP segments discarded due to data length shorter than segment length.
    Discards for Old Timestamp
    Number of inbound TCP segments discarded due to old timestamp.
    Segments Completely Duplicate
    Number of inbound TCP segments with all data before current TCP window.
    Segments Partially Duplicate
    Number of inbound TCP segments with some data before current TCP window.
    Segments Completely After Window
    Number of inbound TCP segments with all data after current TCP window.
    Segments Partially After Window
    Number of inbound TCP segments with some data after current TCP window.
    Segments Out of Order
    Number of inbound TCP segments that did not contain the next expected sequence number.
    Segments Received After Close
    Number of inbound TCP segments received after corresponding sockets have been closed.
    Window Probes Received
    Number of inbound TCP segments processed while current receive window size is 0.
    Window Updates Received
    Number of inbound TCP segments that only change receive window size.
    Segments Sent
    The total number of segments sent.
    Guideline: This value, when displayed for TCP statistics, includes the number of RDMA outbound operations that are processed across all SMC-Rand SMC-D links. To determine the number of segments that were sent on TCP connections that do not traverse SMC-R links, subtract the value for Segments Sent displayed under SMCR Statistics from this value. To determine the number of segments that were sent on TCP connections that do not traverse SMC-D links, subtract the value for Segments Sent displayed under SMCD Statistics from this value.
    Note: This value is an ever increasing 32-bit counter that is subject to wrap during the duration the TCP/IP stack is active.
    Window Updates Sent
    Number of outbound TCP segments that only change receive window size.
    Delayed ACKs Sent
    Number of delayed outbound TCP acknowledgments.
    Resets Sent
    Number of TCP segments sent containing the RST flag.
    Guideline: This value, when displayed for TCP statistics, includes the number of TCP connections that were using SMC-R and SMC-D links. To determine the number of these segments that were sent for TCP connections that were not using SMC-R links, subtract the value for Resets Sent displayed under SMCR Statistics from this value. To determine the number of these segments that were sent for TCP connections that were not using SMC-D links, subtract the value for Resets Sent displayed under SMCD Statistics from this value.
    Segments Retransmitted
    The total number of segments retransmitted.
    Retransmit Timeouts
    Number of TCP retransmit timer pops.
    Connections Dropped by Retransmit
    Number of TCP connections dropped due to retransmit threshold exceeded.
    Path MTU Discovery Retransmits
    Number of outbound TCP segments retransmitted due to path MTU discovery.
    Path MTU Beyond Retransmit Limit
    Number of TCP connections that exceeded path MTU discovery retransmit threshold.
    Window Probes Sent
    Number of outbound window probe requests.
    Connections Dropped during Probe
    Number of TCP connections dropped due to no response while sending window probe requests.
    KeepAlive Probes Sent
    Number of keepalive probe requests. This value includes the number of TCP connections across SMC-R links.
    Connections Dropped by KeepAlive
    Number of TCP connections dropped because of no response when sending keepalive probe requests. This value includes the number of TCP connections across SMC-R links.
    Connections Dropped by Finwait2
    Number of TCP connections dropped because of FINWAIT2 timer expiring before receiving FIN segments. This value includes the number of TCP connections across SMC-R links.
    Configured Ephemeral Ports
    Number of configured ephemeral ports to be assigned for TCP applications.
    Ephemeral Ports In Use
    The number of ephemeral ports currently in use by TCP applications.
    Ephemeral Ports Max Usage
    The highest number of ephemeral ports in use by TCP applications at any time.
    Ephemeral Ports Exhausted
    The number of times a bind() request failed because all available ephemeral ports were in use.
  • The following describes the SMC-D statistics that are displayed:
    Current Established SMC Links
    The current number of active SMC-D links.
    Active SMC Links Opened
    The number of times that an SMC-D link was established and this stack acted in the server role during link establishment.
    Passive SMC Links Opened
    The number of times that an SMC-D link was established and this stack acted in the client role during link establishment.
    SMC Links Closed
    The number of SMC-D links that were closed.
    Current Established Connections
    The number of TCP connections over SMC-D links for which the current state is either ESTABLISHED or CLOSE-WAIT.
    Active Connection Opened
    The number of times that TCP connections over SMC-D links made a direct transition to the SYN-SENT state from the CLOSED state.
    Passive Connection Opened
    The number of times that TCP connections over SMC-D links made a direct transition to the SYN-RCVD state from the LISTEN state.
    Connections Closed
    The number of TCP connections over SMC-D links that have corresponding sockets closed.
    Segments Received
    The number of SMC-D inbound operations that were processed across all SMC-D links.
    Segments Sent
    The number of SMC-D outbound operations that were processed across all SMC-D links.
    Resets Sent
    The number of SMC-D outbound operations that contained the abnormal close flag. This flag is set when the connection is abnormally terminated. For example, the TCP connection was Reset.
    Resets Received
    The number of SMC-D inbound operations that contained the abnormal close flag. This flag is set when the connection is abnormally terminated. For example, the TCP connection was Reset.
  • The following describes the SMC-R statistics that are displayed:
    Current Established SMC Links
    The current number of active SMC-R links.
    SMC Link Activation Time Outs
    The number of times that an attempt occurred to establish an SMC-R link, but the attempt failed because of timeout conditions.
    Active SMC Links Opened
    The number of times that an SMC-R link was established and this stack acted in the server role during link establishment.
    Passive SMC Links Opened
    The number of times that an SMC-R link was established and this stack acted in the client role during link establishment.
    SMC Links Closed
    The number of SMC-R links that were closed.
    Current Established Connections
    The number of TCP connections over SMC-R links for which the current state is either ESTABLISHED or CLOSE-WAIT.
    Active Connection Opened
    The number of times that TCP connections over SMC-R links made a direct transition to the SYN-SENT state from the CLOSED state.
    Passive Connection Opened
    The number of times that TCP connections over SMC-R links made a direct transition to the SYN-RCVD state from the LISTEN state.
    Connections Closed
    The number of TCP connections over SMC-R links that have corresponding sockets closed.
    Segments Received
    The number of SMC-R inbound operations that were processed across all SMC-R links.
    Segments Sent
    The number of SMC-R outbound operations that were processed across all SMC-R links.
    Resets Sent
    The number of SMC-R outbound operations that contained the abnormal close flag. This flag is set when the connection is abnormally terminated. For example, the TCP connection was Reset.
    Resets Received
    The number of SMC-R inbound operations that contained the abnormal close flag. This flag is set when the connection is abnormally terminated. For example, the TCP connection was Reset.
  • The following describes the UDP statistics displayed:
    Datagrams Received
    The total number of UDP datagrams delivered to UDP users.
    No Port Errors
    The total number of received UDP datagrams for which there was no application at the destination port.
    Receive Errors
    The number of received UDP datagrams that could not be delivered for reasons other than the lack of an application at the destination port.
    Datagrams Sent
    The total number of UDP datagrams sent.
    Configured Ephemeral Ports
    Number of configured ephemeral ports to be assigned for UDP applications.
    Ephemeral Ports In Use
    The number of ephemeral ports currently in use by UDP applications.
    Ephemeral Ports Max Usage
    The highest number of ephemeral ports in use by UDP applications at any time.
    Ephemeral Ports Exhausted
    The number of times a bind() request failed because all available ephemeral ports were in use.