Documentation of variables for the Web100 TCP Kernel Instrumentation Set (KIS) project. Matt Mathis Jeffrey Semke Raghu Reddy John Heffner Pittsburgh Supercomputing Center Web 100 Project (c) 2010 All rights reserved. This document contains incomplete and unpublished research results. This interim version is provided only to enable developers to build an initial tool set. Future version of this document are likely to differ from this version in incompatible ways -- newer versions will completely supersede this version. Web100 backport version: differences with RFC4898 have been annotated, and the descriptions have been brought back into alignment with Web100. Scope: {Web100, RFC4898, both} # indicates where implemented Variables that appear in both may have been renamed. Variables that start with "_" were deprecated. Terminology: Local Host: the host from which the KIS was read Remote Host: a host that has a TCP connection between the local host and itself SNMP Data Types taken from RFC1902 "Structure of Management Information for Version 2 of the Simple Network Management Protocol (SNMPv2)" ------------------------------------------------------------------------------ VariableName: LocalAddress Scope: Web100 ShortDescr: Local IP Address ProcType: Ip_Address Description: IP Address of the host from which the KIS was read. R/W: read-only ------------------------------------------------------------------------------ VariableName: LocalAddressType Scope: Web100 ShortDescr: Local Address Type ProcType: Integer Description: The address type of tcpEStatsConnectLocalAddress. Only ipv4(1) and ipv6(2) are expected. R/W: read-only ------------------------------------------------------------------------------ VariableName: LocalPort Scope: Web100 ShortDescr: Local Port Number ProcType: Unsigned16 Description: The Local Host's TCP port number for a connection. R/W: read-only ------------------------------------------------------------------------------ VariableName: RemAddress Scope: Web100 RenameFrom: RemoteAddress ShortDescr: Remote IP Address ProcType: Ip_Address Description: IP Address of the Remote host's end of a connection. R/W: read-only ------------------------------------------------------------------------------ VariableName: RemPort Scope: Web100 RenameFrom: RemotePort ShortDescr: Remote Port Number ProcType: Unsigned16 Description: The Remote Host's TCP port number for a connection. R/W: read-only ------------------------------------------------------------------------------ CATEGORY: WAD CatDescr: Work Around Daemon for the Net100 project. These controls are not safe for general use. ------------------------------------------------------------------------------ VariableName: WAD_IFQ Scope: Web100 ShortDescr: Disable enter_cwr when IF queue is full ProcType: Gauge32 Description: Disable enter_cwr when IF queue is full R/W: read-write ------------------------------------------------------------------------------ VariableName: WAD_MaxBurst Scope: Web100 ShortDescr: Allow bursts when cwnd is greater than awnd ProcType: Gauge32 Description: Cwnd is limited to WAD_MaxBurst above the actual window. Set it very large if you want no burst suppression. The system default is 3. R/W: read-write ------------------------------------------------------------------------------ VariableName: WAD_MaxSsthresh Scope: Web100 ShortDescr: Floyd modified slowstart ProcType: Gauge32 Description: Floyd modified slowstart R/W: read-write ------------------------------------------------------------------------------ VariableName: WAD_NoAI Scope: Web100 ShortDescr: Disable the Additive Increase ProcType: Integer Description: Disable the Additive Increase R/W: read-write ------------------------------------------------------------------------------ VariableName: WAD_CwndAdjust Scope: Web100 ShortDescr: Adjust Cwnd once by the given delta (segments) ProcType: Integer32 Description: Adjust Cwnd once by the given delta (segments). R/W: read-write ------------------------------------------------------------------------------ The following objects reflect TCP options carried on the SYN or SYN-ACK. These options are used to provide additional protocol parameters or to enable various optional TCP features or algorithms. Except as noted, the TCP protocol does not permit these options to change after the SYN exchange. ------------------------------------------------------------------------------ VariableName: ActiveOpen Scope: both ShortDescr: True if local host was the one that sent the SYN. Refer: RFC793, Transmission Control Protocol ProcType: TruthValue Description: True(1) if the local connection traversed the SYN-SENT state, else false(2). R/W: read-only ------------------------------------------------------------------------------ VariableName: MSSSent Scope: RFC4898 ShortDescr: Mss Option sent Refer: RFC1122, Requirements for Internet Hosts - Communication Layers ProcType: Unsigned32 Description: The value sent in an MSS option, or zero if none. R/W: read-only ------------------------------------------------------------------------------ VariableName: MSSRcvd Scope: both ShortDescr: MSS Option received Refer: RFC1122, Requirements for Internet Hosts - Communication Layers ProcType: Unsigned32 Description: The value received in an MSS option, or zero if none. R/W: read-only ------------------------------------------------------------------------------ VariableName: WinScaleSent Scope: both # RenameFrom: SendWinScale ShortDescr: Requested Window Scale Out Refer: RFC1323, TCP Extensions for High Performance ProcType: Integer32 PossibleValues: (-1..14) Description: The value of the transmitted window scale option if one was sent; otherwise, a value of -1. Note that if both tcpEStatsStackWinScaleSent and tcpEStatsStackWinScaleRcvd are not -1, then Rcv.Wind.Scale will be the same as this value and used to scale receiver window announcements from the local host to the remote host. R/W: read-only ------------------------------------------------------------------------------ VariableName: WinScaleRcvd Scope: both # RenameFrom: RecvWinScale ShortDescr: requested window scale Refer: RFC1323, TCP Extensions for High Performance ProcType: Integer32 PossibleValues: (-1..14) Description: The value of the received window scale option if one was received; otherwise, a value of -1. Note that if both tcpEStatsStackWinScaleSent and tcpEStatsStackWinScaleRcvd are not -1, then Snd.Wind.Scale will be the same as this value and used to scale receiver window announcements from the remote host to the local host. R/W: read-only ------------------------------------------------------------------------------ VariableName: SACK Scope: Web100 RenameFrom: SACKEnabled ShortDescr: SACK Enabled Refer: RFC2018, TCP Selective Acknowledgement Options ProcType: TruthValue Description: True(1) if SACK has been negotiated on, else false(2). R/W: read-only ------------------------------------------------------------------------------ VariableName: TimeStamps Scope: both RenameFrom: TimestampsEnabled ShortDescr: Timestamps Enabled Refer: RFC1323, TCP Extensions for High Performance ProcType: TcpEStatsNegotiated Description: Enabled(1) if TCP timestamps have been negotiated on, selfDisabled(2) if they are disabled or not implemented on the local host, or peerDisabled(3) if not negotiated by the remote hosts. R/W: read-only ------------------------------------------------------------------------------ VariableName: ECN Scope: both RenameFrom: ECNEnabled ShortDescr: Explicit Congestion Notification is Enabled Refer: RFC3168, The Addition of Explicit Congestion Notification (ECN) to IP ProcType: TcpEStatsNegotiated Description: Enabled(1) if Explicit Congestion Notification (ECN) has been negotiated on, selfDisabled(2) if it is disabled or not implemented on the local host, or peerDisabled(3) if not negotiated by the remote hosts. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndWindScale Scope: Web100 RenameFrom: SndWinScale ShortDescr: Window scale used by the sender to decode snd.wnd Refer: RFC1323, TCP Extensions for High Performance ProcType: Integer Description: The value of Snd.Wind.Scale. Note that tcpEStatsStackSndWindScaleXXX is either zero or the same as tcpEStatsStackWinScaleRcvdXXX. R/W: read-only ------------------------------------------------------------------------------ VariableName: RcvWindScale Scope: Web100 RenameFrom: RcvWinScale ShortDescr: Window scale used by the receiver to encode seg.wnd Refer: RFC1323, TCP Extensions for High Performance ProcType: Integer Description: The value of Rcv.Wind.Scale. Note that tcpEStatsStackRcvWindScaleXXX is either zero or the same as tcpEStatsStackWinScaleSentXXX. R/W: read-only ------------------------------------------------------------------------------ VariableName: WillSendSACK Scope: RFC4898 ShortDescr: SACKok was sent in SYN or SYN-ACK Refer: RFC2018, TCP Selective Acknowledgement Options ProcType: TcpEStatsNegotiated Description: Enabled(1) if the local host will send SACK options selfDisabled(2) if SACK is disabled or not implemented on the local host, or peerDisabled(3) if the remote host did not send the SACK-permitted option. Note that SACK negotiation is not symmetrical. SACK can enabled on one side of the connection and not the other. R/W: read-only ------------------------------------------------------------------------------ VariableName: WillUseSACK Scope: RFC4898 ShortDescr: SACKok was seen in SYN or SYN-ACK Refer: RFC2018, TCP Selective Acknowledgement Options ProcType: TcpEStatsNegotiated Description: Enabled(1) if the local host will process SACK options selfDisabled(2) if SACK is disabled or not implemented on the local host, or peerDisabled(3) if the remote host sends duplicate ACKs without SACK options, or the local host otherwise decides not to process received SACK options. Unlike other TCP options, the remote data receiver cannot explicitly indicate if it is able to generate SACK options. When sending data, the local host has to deduce if the remote receiver is sending SACK options. This object can transition from Enabled(1) to peerDisabled(3) after the SYN exchange. Note that SACK negotiation is not symmetrical. SACK can enabled on one side of the connection and not the other. R/W: read-only ------------------------------------------------------------------------------ VariableName: TimeStampSent Scope: RFC4898 ShortDescr: Timestamp sent in SYN or SYN-ACK Refer: RFC1323, TCP Extensions for High Performance ProcType: TruthValue Description: True(1) if Timestamp option was sent, else false(2). R/W: read-only ------------------------------------------------------------------------------ VariableName: TimeStampRcvd Scope: RFC4898 ShortDescr: Timestamp received in SYN or SYN-ACK Refer: RFC1323, TCP Extensions for High Performance ProcType: TruthValue Description: True(1) if Timestamp option was received, else false(2). R/W: read-only ------------------------------------------------------------------------------ The following objects provide statistics on aggregate segments and data sent on a connection. These provide a direct measure of the Internet capacity consumed by a connection. ------------------------------------------------------------------------------ VariableName: SegsOut RenameFrom: PktsOut Scope: both ShortDescr: Total Segments Out ProcType: ZeroBasedCounter32 Description: The total number of segments sent. R/W: read-only ------------------------------------------------------------------------------ VariableName: DataSegsOut RenameFrom: DataPktsOut Scope: both ShortDescr: Data Segments Out ProcType: ZeroBasedCounter32 Description: The number of segments sent containing a positive length data segment. R/W: read-only ------------------------------------------------------------------------------ VariableName: DataOctetsOut Scope: RFC4898 ShortDescr: Data Octets Out Units: octets ProcType: ZeroBasedCounter32 Description: The number of octets of data contained in transmitted segments, including retransmitted data. Note that this does not include TCP headers. R/W: read-only ------------------------------------------------------------------------------ VariableName: HCDataOctetsOut RenameFrom: DataBytesOut Scope: both ShortDescr: Data Octets Out Units: octets ProcType: ZeroBasedCounter64 Description: The number of octets of data contained in transmitted segments, including retransmitted data, on systems that can transmit more than 10 million bits per second. Note that this does not include TCP headers. R/W: read-only ------------------------------------------------------------------------------ VariableName: SegsRetrans RenameFrom: PktsRetrans Scope: both ShortDescr: Segments With Retransmitted Data Refer: RFC793, Transmission Control Protocol ProcType: ZeroBasedCounter32 Description: The number of segments transmitted containing at least some retransmitted data. R/W: read-only ------------------------------------------------------------------------------ VariableName: OctetsRetrans RenameFrom: BytesRetrans Scope: both ShortDescr: Retransmitted Octets Refer: RFC793, Transmission Control Protocol Units: octets ProcType: ZeroBasedCounter32 Description: The number of octets retransmitted. R/W: read-only ------------------------------------------------------------------------------ VariableName: SegsIn RenameFrom: PktsIn Scope: both ShortDescr: Total Segments In ProcType: ZeroBasedCounter32 Description: The total number of segments received. R/W: read-only ------------------------------------------------------------------------------ VariableName: DataSegsIn RenameFrom: DataPktsIn Scope: both ShortDescr: Total Data Segments In ProcType: ZeroBasedCounter32 Description: The number of segments received containing a positive length data segment. R/W: read-only ------------------------------------------------------------------------------ VariableName: DataOctetsIn Scope: RFC4898 ShortDescr: Data Octets In Units: octets ProcType: ZeroBasedCounter32 Description: The number of octets contained in received data segments, including retransmitted data. Note that this does not include TCP headers. R/W: read-only ------------------------------------------------------------------------------ VariableName: HCDataOctetsIn RenameFrom: DataBytesIn Scope: both ShortDescr: Data Octets In Units: octets ProcType: ZeroBasedCounter64 Description: The number of octets contained in received data segments, including retransmitted data, on systems that can receive more than 10 million bits per second. Note that this does not include TCP headers. R/W: read-only ------------------------------------------------------------------------------ VariableName: Duration Scope: Web100 RenameFrom: CurrTime ShortDescr: Elapsed microseconds Units: microseconds ProcType: ZeroBasedCounter64 Description: The number of microseconds since StartTimeStamp. NB: this is not sampled on protocol events, as are ElapsedSecs and ElapsedMicroSecs. R/W: read-only ------------------------------------------------------------------------------ VariableName: ElapsedSecs Scope: RFC4898 ShortDescr: Elapsed seconds Units: seconds ProcType: ZeroBasedCounter32 Description: The seconds part of the time elapsed between tcpEStatsPerfStartTimeStamp and the most recent protocol event (segment sent or received). R/W: read-only ------------------------------------------------------------------------------ VariableName: ElapsedMicroSecs Scope: RFC4898 ShortDescr: Elapsed micro Seconds Units: microseconds ProcType: ZeroBasedCounter32 Description: The micro-second part of time elapsed between tcpEStatsPerfStartTimeStamp to the most recent protocol event (segment sent or received). This may be updated in whatever time granularity is the system supports. R/W: read-only ------------------------------------------------------------------------------ VariableName: StartTimeStamp Scope: both RenameFrom: StartTimeSec StartTime StartTimeUsec ShortDescr: Start Time ProcType: Integer32 SNMPType: DateAndTime Description: Time at which this row was created and all ZeroBasedCounters in the row were initialized to zero. R/W: read-only ------------------------------------------------------------------------------ The following objects can be used to fit minimal performance models to the TCP data rate. ------------------------------------------------------------------------------ VariableName: CurMSS Scope: both RenameFrom: CurrentMSS ShortDescr: Current Maximum Segment Size Refer: RFC1122, Requirements for Internet Hosts - Communication Layers Units: octets ProcType: Gauge32 Description: The current maximum segment size (MSS), in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: PipeSize Scope: RFC4898 ShortDescr: Octets in flight Refer: RFC793, RFC2581, RFC3517 Units: octets ProcType: Gauge32 Description: The TCP senders current estimate of the number of unacknowledged data octets in the network. While not in recovery (e.g., while the receiver is not reporting missing data to the sender) this is precisely the same as ``Flight size'' as defined in RFC2581, which can be computed as SND.NXT minus SND.UNA. [RFC793] During recovery the TCP sender has incomplete information about the state of the network (e.g., which segments are lost vs reordered, especially if the return path is also dropping TCP acknowledgments). Current TCP standards do not mandate any specific algorithm for estimating the number of unacknowledged data octets in the network. RFC3517 describes a conservative algorithm to use SACK information to estimate the number of unacknowledged data octets in the network. tcpEStatsPerfPipeSize object SHOULD be the same as ``pipe'' as defined in RFC3517 if it is implemented. (Note that while not in recovery the pipe algorithm yields the same values as flight size). If RFC3517 is not implemented, the data octets in flight SHOULD be estimated as SND.NXT minus SND.UNA adjusted by some measure of the data that has left the network and retransmitted data. For example, with Reno or NewReno style TCP, the number of duplicate acknowledgment is used to count the number of segments that have left the network. I.e., PipeSize=SND.NXT-SND.UNA+(retransmits-dupacks)*CurMSS R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxPipeSize Scope: RFC4898 ShortDescr: Max Octets in flight Refer: RFC793, RFC2581, RFC3517 Units: octets ProcType: Gauge32 Description: The maximum value of tcpEStatsPerfPipeSize, for this connection. R/W: read-only ------------------------------------------------------------------------------ The following optional objects instrument the round trip time estimator and the retransmission timeout timer. ------------------------------------------------------------------------------ VariableName: SampleRTT Scope: both RenameFrom: SampledRTT ShortDescr: Most recent RTT sample Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The most recent raw round trip time measurement used in calculation of the RTO. R/W: read-only ------------------------------------------------------------------------------ VariableName: SmoothedRTT Scope: both ShortDescr: Smoothed RTT Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The smoothed round trip time used in calculation of the RTO. See SRTT in [RFC2988]. R/W: read-only ------------------------------------------------------------------------------ VariableName: RTTVar Scope: both ShortDescr: RTT variation Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The round trip time variation used in calculation of the RTO. See RTTVAR in [RFC2988]. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxRTT Scope: both ShortDescr: Maximum RTT Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The maximum sampled round trip time. R/W: read-only ------------------------------------------------------------------------------ VariableName: MinRTT Scope: both ShortDescr: Minimum RTT Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The minimum sampled round trip time. R/W: read-only ------------------------------------------------------------------------------ VariableName: SumRTT Scope: both ShortDescr: Cumulative RTT Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: ZeroBasedCounter32 Description: The sum of all sampled round trip times. Note that the change in tcpEStatsPathSumRTT divided by the change in tcpEStatsPathCountRTT is the mean RTT, uniformly averaged over an enter interval. R/W: read-only ------------------------------------------------------------------------------ VariableName: HCSumRTT Scope: RFC4898 ShortDescr: Cumulative RTT Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: ZeroBasedCounter64 Description: The sum of all sampled round trip times, on all systems that implement multiple concurrent RTT measurements. Note that the change in tcpEStatsPathHCSumRTT divided by the change in tcpEStatsPathCountRTT is the mean RTT, uniformly averaged over an enter interval. R/W: read-only ------------------------------------------------------------------------------ VariableName: CountRTT Scope: both ShortDescr: Count of samples in SumRTT Refer: RFC2988, Computing TCP's Retransmission Timer ProcType: ZeroBasedCounter32 Description: The number of round trip time samples included in tcpEStatsPathSumRTT and tcpEStatsPathHCSumRTT. R/W: read-only ------------------------------------------------------------------------------ VariableName: CurRTO Scope: both RenameFrom: CurrentRTO ShortDescr: Current Retransmission Timer Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The current value of the retransmit timer RTO. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxRTO Scope: both ShortDescr: Maximum Retransmission Timer Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The maximum value of the retransmit timer RTO. R/W: read-only ------------------------------------------------------------------------------ VariableName: MinRTO Scope: both ShortDescr: Minimum Retransmission Timer Refer: RFC2988, Computing TCP's Retransmission Timer Units: milliseconds ProcType: Gauge32 Description: The minimum value of the retransmit timer RTO. R/W: read-only ------------------------------------------------------------------------------ The following optional objects instrument unusual protocol events that probably indicate implementation problems in the protocol or path. ------------------------------------------------------------------------------ VariableName: SoftErrors Scope: RFC4898 ShortDescr: Soft Errors Refer: RFC793, Transmission Control Protocol ProcType: ZeroBasedCounter32 Description: The number of segments that fail various consistency tests during TCP input processing. Soft errors might cause the segment to be discard but some do not. Some of these soft errors cause the generation of a TCP acknowledgment, others are silently discarded. R/W: read-only ------------------------------------------------------------------------------ VariableName: SoftErrorReason Scope: RFC4898 ShortDescr: Identifies the consistency test that most recently failed Refer: RFC793, Transmission Control Protocol ProcType: INTEGER R/W: read-only PossibleValues: belowDataWindow(1) aboveDataWindow(2) belowAckWindow(3) aboveAckWindow(4) belowTSWindow(5) aboveTSWindow(6) dataCheckSum(7) otherSoftError(8) Description: This object identifies which consistency test most recently failed during tcp input processing. This object SHOULD be set every time tcpEStatsStackSoftErrors is incremented. The codes are as follows: belowDataWindow(1) - All data in the segment is below SND.UNA. (Normal for keep-alives and zero window probes). aboveDataWindow(2) - Some data in the segment is above SND.WND. (Indicates an implementation bug or possible attack). belowAckWindow(3) - ACK below SND.UNA. (Indicates that the return path is reordering ACKs) aboveAckWindow(4) - An ACK for data that we have not sent. (Indicates an implementation bug or possible attack). belowTSWindow(5) - TSecr on the segment is older than the current TS.Recent (Normal for the rare case where PAWS detects data reordered by the network.) aboveTSWindow(6) - TSecr on the segment is newer than the current TS.Recent. (Indicates an implementation bug or possible attack). dataCheckSum(7) - Incorrect checksum. Note that this value is intrinsically fragile, because the header fields used to identify the connection may have been corrupted. otherSoftError(8) - All other soft errors not listed above." ------------------------------------------------------------------------------ The following optional objects provide information about how TCP is using the IP layer. ------------------------------------------------------------------------------ VariableName: IpTtl Scope: RFC4898 ShortDescr: TTL on the incoming segment Refer: RFC791, Internet Protocol ProcType: Unsigned32 Description: The value of the TTL field carried in the most recently received IP header. This is sometimes useful to detect changing or unstable routes. R/W: read-only ------------------------------------------------------------------------------ VariableName: IpTosIn Scope: RFC4898 ShortDescr: The DSCP field of the incoming segment. Refer: RFC3260, New Terminology and Clarifications for Diffserv ProcType: Integer32 SNMPType: OCTET STRING PossibleValues: (SIZE(1)) Description: The value of the IPv4 Type Of Service octet, or the IPv6 traffic class octet, carried in the most recently received IP header. This is useful to diagnose interactions between TCP and any IP layer packet scheduling and delivery policy, which might be in effect to implement Diffserv. R/W: read-only ------------------------------------------------------------------------------ VariableName: IpTosOut Scope: RFC4898 ShortDescr: The DSCP field of the incoming segment. Refer: RFC3260, New Terminology and Clarifications for Diffserv ProcType: Integer32 SNMPType: OCTET STRING PossibleValues: (SIZE(1)) Description: The value of the IPv4 Type Of Service octet, or the IPv6 traffic class octet, carried in the most recently transmitted IP header. This is useful to diagnose interactions between TCP and any IP layer packet scheduling and delivery policy, which might be in effect to implement Diffserv. R/W: read-only ------------------------------------------------------------------------------ The following objects provide throughput statistics for the connection including sequence numbers and elapsed application data. These permit direct observation of the applications progress, in terms of elapsed data delivery and elapsed time. ------------------------------------------------------------------------------ VariableName: SndUna Scope: both RenameFrom: snd_una ShortDescr: Oldest Unacknowledged Sequence Number. Refer: RFC793, Transmission Control Protocol ProcType: Counter32 Description: The value of SND.UNA, the oldest unacknowledged sequence number. Note that SND.UNA is a TCP state variable that is congruent to Counter32 semantics. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndNxt Scope: both RenameFrom: snd_nxt ShortDescr: Next Sequence Number to be Sent Refer: RFC793, Transmission Control Protocol ProcType: Unsigned32 Description: The value of SND.NXT, the next sequence number to be sent. Note that tcpEStatsAppSndNxt is not monotonic (and thus not a counter) because TCP sometimes retransmits lost data by pulling tcpEStatsAppSndNxt back to the missing data. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndMax Scope: both RenameFrom: snd_max ShortDescr: Maximum Value of snd_nxt Refer: RFC793, Transmission Control Protocol ProcType: Counter32 Description: The farthest forward (right most or largest) SND.NXT value. Note that this will be equal to tcpEStatsAppSndNxt except when tcpEStatsAppSndNxt is pulled back during recovery. R/W: read-only ------------------------------------------------------------------------------ VariableName: ThruOctetsAcked Scope: RFC4898 ShortDescr: Total throughput octets sent Units: octets ProcType: ZeroBasedCounter32 Description: The number of octets for which cumulative acknowledgments have been received. Note that this will be the sum of changes to tcpEStatsAppSndUna. R/W: read-only ------------------------------------------------------------------------------ VariableName: HCThruOctetsAcked RenameFrom: ThruBytesAcked Scope: both ShortDescr: Total throughput octets sent Units: octets ProcType: ZeroBasedCounter64 Description: The number of octets for which cumulative acknowledgments have been received, on systems that can receive more than 10 million bits per second. Note that this will be the sum of changes in tcpEStatsAppSndUna. R/W: read-only ------------------------------------------------------------------------------ VariableName: RcvNxt Scope: both RenameFrom: rcv_nxt ShortDescr: Next sequence number expected on an incoming segment Refer: RFC793, Transmission Control Protocol ProcType: Counter32 Description: The value of RCV.NXT. The next sequence number expected on an incoming segment, and the left or lower edge of the receive window. Note that RCV.NXT is a TCP state variable that is congruent to Counter32 semantics. R/W: read-only ------------------------------------------------------------------------------ VariableName: ThruOctetsReceived Scope: RFC4898 ShortDescr: Total throughput octets received Units: octets ProcType: ZeroBasedCounter32 Description: The number of octets for which cumulative acknowledgments have been sent. Note that this will be the sum of changes to tcpEStatsAppRcvNxt. R/W: read-only ------------------------------------------------------------------------------ VariableName: HCThruOctetsReceived RenameFrom: ThruBytesReceived Scope: both ShortDescr: Total throughput octets received Units: octets ProcType: ZeroBasedCounter64 Description: The number of octets for which cumulative acknowledgments have been sent, on systems that can transmit more than 10 million bits per second. Note that this will be the sum of changes in tcpEStatsAppRcvNxt. R/W: read-only ------------------------------------------------------------------------------ The following optional objects can be used to quickly identify which subsystems are limiting TCP performance. There are three parallel pairs of instruments that measure the extent to which TCP performance is limited by the announced receiver window (indicating a receiver bottleneck), the current congestion window or retransmission timeout (indicating a path bottleneck) and all others events (indicating a sender bottleneck). These instruments SHOULD be updated every time the TCP output routine stops sending data. The elapsed time since the previous stop is accumulated into the appropriate object as determined by the previous stop reason (e.g., stop state). The current stop reason determines which timer will be updated the next time TCP output stops. Since there is no explicit stop at the beginning of a timeout, it is necessary to retroactively reclassify the previous stop as "Congestion Limited". ------------------------------------------------------------------------------ VariableName: SndLimTransRwin Scope: both ShortDescr: Receiver Limited Transitions Refer: RFC793, Transmission Control Protocol ProcType: ZeroBasedCounter32 Description: The number of transitions into the "Receiver Limited" state from either the "Congestion Limited" or "Sender Limited" states. This state is entered whenever TCP transmission stops because the sender has filled the announced receiver window. I.e., when SND.NXT has advanced to SND.UNA + SND.WND - 1 as described in RFC 793. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimTransCwnd Scope: both ShortDescr: Congestion Limited Transitions Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of transitions into the "Congestion Limited" state from either the "Receiver Limited" or "Sender Limited" states. This state is entered whenever TCP transmission stops because the sender has reached some limit defined by congestion control (e.g., cwnd) or other algorithms (retransmission timeouts) designed to control network traffic. See the definition of "CONGESTION WINDOW" in RFC 2581. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimTransSnd Scope: both RenameFrom: SndLimTransSender ShortDescr: Sender Limited Transitions ProcType: ZeroBasedCounter32 Description: The number of transitions into the "Sender Limited" state from either the "Receiver Limited" or "Congestion Limited" states. This state is entered whenever TCP transmission stops due to some sender limit such as running out of application data or other resources and the Karn algorithm. When TCP stops sending data for any reason which cannot be classified as Receiver Limited or Congestion Limited it MUST be treated as Sender Limited. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimTimeRwin Scope: both ShortDescr: Receiver Limited Time Units: milliseconds ProcType: ZeroBasedCounter32 Description: The cumulative time spent in the "Receiver Limited" state. See tcpEStatsPerfSndLimTransRwin. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimTimeCwnd Scope: both ShortDescr: Congestion Limited Time Units: milliseconds ProcType: ZeroBasedCounter32 Description: The cumulative time spent in the "Congestion Limited" state. See tcpEStatsPerfSndLimTransCwnd. When there is a retransmission timeout, it SHOULD be counted in tcpEStatsPerfSndLimTimeCwnd (and not the cumulative time for some other state.) R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimTimeSnd Scope: both RenameFrom: SndLimTimeSender ShortDescr: Sender Limited Time Units: milliseconds ProcType: ZeroBasedCounter32 Description: The cumulative time spent in the "Sender Limited" state. See tcpEStatsPerfSndLimTransSnd. R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimBytesRwin Scope: Web100 ShortDescr: deprecated Units: Bytes ProcType: ZeroBasedCounter64 Description: Parallel to SndLimTimeRwin, but not useful R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimBytesCwnd Scope: Web100 ShortDescr: deprecated Units: Bytes ProcType: ZeroBasedCounter64 Description: Parallel to SndLimTimeCwin, but not useful R/W: read-only ------------------------------------------------------------------------------ VariableName: SndLimBytesSender Scope: Web100 ShortDescr: deprecated Units: Bytes ProcType: ZeroBasedCounter64 Description: Parallel to SndLimTimeSnd, but not useful R/W: read-only ------------------------------------------------------------------------------ The following two objects reflect the current state of the connection. ------------------------------------------------------------------------------ VariableName: State Scope: both ShortDescr: TCP State Refer: RFC793, Transmission Control Protocol ProcType: INTEGER Description: An integer value representing the connection state from the TCP State Transition Diagram. The value listen(2) is included only for parallelism to the old tcpConnTable, and SHOULD NOT be used because the listen state in managed by the tcpListenerTable. The value DeleteTcb(12) is included only for parallelism to the tcpConnTable mechanism for stopping connections, although this table does not permit writing. R/W: read-only PossibleValues: tcpESStateClosed(1) tcpESStateListen(2) tcpESStateSynSent(3) tcpESStateSynReceived(4) tcpESStateEstablished(5) tcpESStateFinWait1(6) tcpESStateFinWait2(7) tcpESStateCloseWait(8) tcpESStateLastAck(9) tcpESStateClosing(10) tcpESStateTimeWait(11) tcpESStateDeleteTcb(12) ------------------------------------------------------------------------------ VariableName: Nagle Scope: both RenameFrom: NagleEnabled ShortDescr: Nagle Algorithm Enabled Refer: RFC1122, Requirements for Internet Hosts - Communication Layers ProcType: TruthValue Description: True(1) if the Nagle algorithm is being used, else false(2). R/W: read-only ------------------------------------------------------------------------------ The following objects instrument the overall operation of TCP congestion control and data retransmissions. These instruments are sufficient to fit the actual performance to an updated macroscopic performance model [RFC2581] [Mat97] [Pad98]. ------------------------------------------------------------------------------ The following optional objects expose the detailed operation of the congestion control algorithms. ------------------------------------------------------------------------------ VariableName: SlowStart Scope: both ShortDescr: Slow Start Window Opens Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of times the congestion window has been increased by the Slow Start algorithm. R/W: read-only ------------------------------------------------------------------------------ VariableName: CongAvoid Scope: both ShortDescr: Congestion Avoidance Window Opens Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of times the congestion window has been increased by the Congestion Avoidance algorithm. R/W: read-only ------------------------------------------------------------------------------ VariableName: CongSignals Scope: both RenameFrom: CongestionSignals RenameFrom: Recoveries PreCongCountRTT ShortDescr: Total Congestion Signals. Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of multiplicative downward congestion window adjustments due to all forms of congestion signals, including Fast Retransmit, ECN and timeouts. This object summarizes all events that invoke the MD portion of AIMD congestion control, and as such is the best indicator of how cwnd is being affected by congestion. Note that retransmission timeouts multiplicatively reduce the window implicitly by setting ssthresh, and SHOULD be included in tcpEStatsPerfCongSignals. In order to minimize spurious congestion indications due to out-of-order segments, tcpEStatsPerfCongSignals SHOULD be incremented in association with the Fast Retransmit algorithm. R/W: read-only ------------------------------------------------------------------------------ VariableName: OtherReductions Scope: both ShortDescr: Other Congestion Window Reductions Refer: RFC2861, TCP Congestion Window Validation ProcType: ZeroBasedCounter32 Description: The number of congestion window reductions made as a result of anything other than AIMD congestion control algorithms. Examples of non-multiplicative window reductions include Congestion Window Validation [RFC2861] and experimental algorithms such as Vegas [Bra94]. All window reductions MUST be counted as either tcpEStatsPerfCongSignals or tcpEStatsStackOtherReductions. R/W: read-only ------------------------------------------------------------------------------ VariableName: X_OtherReductionsCM Scope: Web100 ShortDescr: Linux specific IFQ backpresure ProcType: ZeroBasedCounter32 Description: Linux specific IFQ backpresure R/W: read-only ------------------------------------------------------------------------------ VariableName: X_OtherReductionsCV Scope: Web100 ShortDescr: Linux specific Congetion Window Validation ProcType: ZeroBasedCounter32 Description: Linux specific Congetion Window Validation R/W: read-only ------------------------------------------------------------------------------ VariableName: CongOverCount Scope: both RenameFrom: CongestionOverCount ShortDescr: Overcounted congestion Signals Refer: RFC3522, The Eifel Detection Algorithm for TCP ProcType: ZeroBasedCounter32 Description: The number of congestion events which were 'backed out' of the congestion control state machine such that the congestion window was restored to a prior value. This can happen due to the Eifel algorithm [RFC3522] or other algorithms which can be used to detect and cancel spurious invocations of the Fast Retransmit Algorithm. Although it may be feasible to undo the effects of spurious invocation of the Fast Retransmit congestion events cannot easily be backed out of tcpEStatsPerfCongSignals and tcpEStatsPathPreCongSumCwnd, etc. R/W: read-only ------------------------------------------------------------------------------ VariableName: CurCwnd Scope: both RenameFrom: CurrentCwnd ShortDescr: Current Congestion Window Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Gauge32 Description: The current congestion window, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxSsCwnd Scope: both RenameFrom: MaxCwnd ShortDescr: Maximum SS Congestion Window Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Gauge32 Description: The maximum congestion window used during Slow Start, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxCaCwnd Scope: RFC4898 ShortDescr: Maximum CA Congestion Window Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Gauge32 Description: The maximum congestion window used during Congestion Avoidance, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: LimCwnd Scope: both ShortDescr: Maximum Congestion Window Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Unsigned32 Description: A control to set the maximum congestion window which may be used, in octets. R/W: read-write ------------------------------------------------------------------------------ VariableName: CurSsthresh Scope: both RenameFrom: CurrentSsthresh ShortDescr: Current Slowstart Threshold Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Gauge32 Description: The current slow start threshold in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxSsthresh Scope: both ShortDescr: Maximum Slowstart Threshold Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Gauge32 Description: The maximum slow start threshold, excluding the initial value. R/W: read-only ------------------------------------------------------------------------------ VariableName: MinSsthresh Scope: both ShortDescr: Minimum Slowstart Threshold Refer: RFC2581, TCP Congestion Control Units: octets ProcType: Gauge32 Description: The minimum slow start threshold. R/W: read-only ------------------------------------------------------------------------------ VariableName: LimSsthresh Scope: RFC4898 ShortDescr: Maximum Slowstart Threshhold Refer: RFC3742, Limited Slow-Start for TCP with Large Congestion Windows Units: octets ProcType: Unsigned32 Description: A control to limit the maximum queue space (in octets) that this TCP connection is likely to occupy during slowstart. It can be implemented with the algorithm described in RFC3742 by setting the max_ssthresh parameter to twice tcpEStatsTuneLimSsthresh. This algorithm can be used to overcome some TCP performance problems over network paths that do not have sufficient buffering to withstand the bursts normally present during slowstart. R/W: read-write ------------------------------------------------------------------------------ VariableName: InRecovery Scope: RFC4898 ShortDescr: Recovery state Refer: RFC2581, TCP Congestion Control ProcType: INTEGER Description: An integer value representing the state of the loss recovery for this connection. tcpESDataContiguous(1) indicates that the remote receiver is reporting contiguous data (no duplicate acknowledgments or SACK options) and that there are no unacknowledged retransmissions. tcpESDataUnordered(2) indicates that the remote receiver is reporting missing or out-of-order data (e.g., sending duplicate acknowledgments or SACK options) and that there are no unacknowledged retransmissions (because the missing data has not yet been retransmitted). tcpESDataRecovery(3) indicates that the sender has outstanding retransmitted data which is still unacknowledged. R/W: read-only PossibleValues: tcpESDataContiguous(1) tcpESDataUnordered(2) tcpESDataRecovery(3) ------------------------------------------------------------------------------ VariableName: FastRetran Scope: both ShortDescr: Fast Retransmits Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of invocations of the Fast Retransmit algorithm. R/W: read-only ------------------------------------------------------------------------------ VariableName: Timeouts Scope: both ShortDescr: Number of Initial Timeouts Refer: RFC2988, Computing TCP's Retransmission Timer ProcType: ZeroBasedCounter32 Description: The number of times the retransmit timeout has expired when the RTO backoff multiplier is equal to one. R/W: read-only. ------------------------------------------------------------------------------ VariableName: SubsequentTimeouts Scope: both ShortDescr: Subsequent (repeated) Timeouts Refer: RFC2988, Computing TCP's Retransmission Timer ProcType: ZeroBasedCounter32 Description: The number of times the retransmit timeout has expired after the RTO has been doubled. See section 5.5 in RFC2988. R/W: read-only ------------------------------------------------------------------------------ VariableName: CurTimeoutCount Scope: both RenameFrom: CurrTimeoutCount ShortDescr: Current Repeated Timeout Count Refer: RFC2988, Computing TCP's Retransmission Timer ProcType: Gauge32 Description: The current number of times the retransmit timeout has expired without receiving an acknowledgment for new data. tcpEStatsStackCurTimeoutCount is reset to zero when new data is acknowledged and incremented for each invocation of section 5.5 in RFC2988. R/W: read-only ------------------------------------------------------------------------------ VariableName: AbruptTimeouts Scope: both ShortDescr: Abrupt Timeouts Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of timeouts that occurred without any immediately preceding duplicate acknowledgments or other indications of congestion. Abrupt Timeouts indicate that the path lost an entire window of data or acknowledgments. Timeouts that are preceded by duplicate acknowledgments or other congestion signals (e.g., ECN) are not counted as abrupt, and might have been avoided by a more sophisticated Fast Retransmit algorithm. R/W: read-only ------------------------------------------------------------------------------ VariableName: DupAcksIn Scope: both ShortDescr: Number of Duplicate ACKs Received Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of duplicate ACKs received. R/W: read-only ------------------------------------------------------------------------------ VariableName: SACKsRcvd Scope: both ShortDescr: Number of SACKs Options Received Refer: RFC2018, TCP Selective Acknowledgement Options ProcType: ZeroBasedCounter32 Description: The number of SACK options received. R/W: read-only ------------------------------------------------------------------------------ VariableName: SACKBlocksRcvd Scope: both ShortDescr: Number of SACKs blocks Received Refer: RFC2018, TCP Selective Acknowledgement Options ProcType: ZeroBasedCounter32 Description: The number of SACK blocks received (within SACK options). R/W: read-only ------------------------------------------------------------------------------ The following optional objects characterize the congestion feedback signals by collecting statistics on how the congestion events are correlated to losses, changes in RTT and other protocol events. ------------------------------------------------------------------------------ VariableName: PreCongSumCwnd Scope: both RenameFrom: SumCwndAtCong ShortDescr: Sum Congestion Window at Congestion Units: octets ProcType: ZeroBasedCounter32 Description: The sum of the values of the congestion window, in octets, captured each time a congestion signal is received. This MUST be updated each time tcpEStatsPerfCongSignals is incremented, such that the change in tcpEStatsPathPreCongSumCwnd divided by the change in tcpEStatsPerfCongSignals is the average window (over some interval) just prior to a congestion signal. R/W: read-only ------------------------------------------------------------------------------ VariableName: PreCongSumRTT Scope: both ShortDescr: Sum of the RTT as measured just before congestion. Units: milliseconds ProcType: ZeroBasedCounter32 Description: Sum of the last sample of the RTT (tcpEStatsPathSampleRTT) prior to received congestion signals. This MUST be updated each time tcpEStatsPerfCongSignals is incremented, such that the change in tcpEStatsPathPreCongSumRTT divided by the change in tcpEStatsPerfCongSignals is the average RTT (over some interval) just prior to a congestion signal. R/W: read-only ------------------------------------------------------------------------------ VariableName: PostCongSumRTT Scope: both ShortDescr: Sum of the RTT as measured just after congestion. Units: octets ProcType: ZeroBasedCounter32 Description: Sum of the first RTT sample following a received congestion signal. Description: Sum of the first sample of the RTT (tcpEStatsPathSampleRTT) following each congestion signal. Such that the change in tcpEStatsPathPostCongSumRTT divided by the change in tcpEStatsPathPostCongCountRTT is the average RTT (over some interval) just after a congestion signal. R/W: read-only ------------------------------------------------------------------------------ VariableName: PostCongCountRTT Scope: both ShortDescr: Count of the RTT as measured just after congestion Units: milliseconds ProcType: ZeroBasedCounter32 Description: The number of RTT samples included in tcpEStatsPathPostCongSumRTT such that the change in tcpEStatsPathPostCongSumRTT divided by the change in tcpEStatsPathPostCongCountRTT is the average RTT (over some interval) just after a congestion signal. R/W: read-only ------------------------------------------------------------------------------ The following optional objects can be used to detect other types of non-loss congestion signals such as source quench or ECN. ------------------------------------------------------------------------------ VariableName: ECNsignals Scope: RFC4898 ShortDescr: All ECN congestion signals Refer: RFC3168, The Addition of Explicit Congestion Notification (ECN) to IP ProcType: ZeroBasedCounter32 Description: The number of congestion signals delivered to the TCP sender via explicit congestion notification (ECN). This is typically the number of segments bearing ECE bits but should also include segments failing the ECN nonce check or other explicit congestion signals. R/W: read-only ------------------------------------------------------------------------------ VariableName: SendStall Scope: both ShortDescr: local resource stalls treated as congestion signals ProcType: ZeroBasedCounter32 Description: The number of interface stalls or other sender local resource limitations that are treated as congestion signals. R/W: read-only ------------------------------------------------------------------------------ VariableName: QuenchRcvd Scope: Web100 ShortDescr: ICMP Quench Messages received ProcType: ZeroBasedCounter32 Description: The number of ICMP quench messages that are treated as congestion signals. R/W: read-only ------------------------------------------------------------------------------ The following optional objects can be used to infer segment reordering on the path from the local sender to the remote receiver. ------------------------------------------------------------------------------ VariableName: RetranThresh Scope: both ShortDescr: Duplicate ACKs needed to trigger FR Refer: RFC2581, TCP Congestion Control ProcType: Gauge32 Description: The number of duplicate acknowledgments required to trigger Fast Retransmit. Note that although this is constant in traditional Reno TCP implementations, it is adaptive in many newer TCPs. R/W: read-only ------------------------------------------------------------------------------ VariableName: NonRecovDAEpisodes Scope: RFC4898 ShortDescr: Dup Ack Episodes that did not trigger FR Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of duplicate acknowledgment episodes that did not trigger a Fast Retransmit because ACK advanced prior to the number of duplicate acknowledgments reaching RetranThresh. In many implementations this is the number of times the "dupacks" counter is set to zero when it is non-zero but less than RetranThresh. Note that the change in tcpEStatsPathNonRecovDAEpisodes divided by the change in tcpEStatsPerfDataSegsOut is an estimate of the frequency of data reordering on the forward path over some interval. R/W: read-only ------------------------------------------------------------------------------ VariableName: SumOctetsReordered Scope: RFC4898 ShortDescr: Sum Octets Reordered Units: octets ProcType: ZeroBasedCounter32 Description: The sum of the amounts SND.UNA advances on the acknowledgment which ends a dup-ack episode without a retransmission. Note the change in tcpEStatsPathSumOctetsReordered divided by the change in tcpEStatsPathNonRecovDAEpisodes is an estimates of the average reordering distance, over some interval. R/W: read-only ------------------------------------------------------------------------------ VariableName: NonRecovDA Scope: both ShortDescr: Duplicate Acks attributed to Out-of-Order Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: Duplicate acks (or SACKS) that did not trigger a Fast Retransmit because ACK advanced prior to the number of duplicate acknowledgments reaching RetranThresh. In many implementations, this is the sum of the "dupacks" counter, just before it is set to zero because ACK advanced without a Fast Retransmit. Note that the change in tcpEStatsPathNonRecovDA divided by the change in tcpEStatsPathNonRecovDAEpisodes is an estimate of the average reordering distance in segments over some interval. R/W: read-only ------------------------------------------------------------------------------ VariableName: SpuriousFrDetected RenameFrom: AckAfterFR Scope: both ShortDescr: ACKs following FR, but not due to FR (way ooo) Refer: RFC3522, The Eifel Detection Algorithm for TCP ProcType: ZeroBasedCounter32 Description: The number of acknowledgments reporting out-of-order segments after the Fast Retransmit algorithm has already retransmitted the segments. (For example as detected by the Eifel algorithm)." R/W: read-only ------------------------------------------------------------------------------ VariableName: SpuriousRtoDetected Scope: RFC4898 ShortDescr: ACKs following FR, but not due to FR (way ooo) ProcType: ZeroBasedCounter32 Description: The number of acknowledgments reporting segments that have already been retransmitted due to a Retransmission Timeout. R/W: read-only ------------------------------------------------------------------------------ VariableName: DSACKDups Scope: both ShortDescr: Duplicate Data DSACK Reports Refer: RFC2883, An Extension to the Selective Acknowledgement (SACK) Option for TCP ProcType: ZeroBasedCounter32 Description: The number of duplicate segments reported to the local host by D-SACK blocks. R/W: read-only ------------------------------------------------------------------------------ The following optional objects instrument path MTU discovery. ------------------------------------------------------------------------------ VariableName: MaxMSS Scope: both ShortDescr: Maximum MSS Refer: RFC1191, Path MTU discovery Units: octets ProcType: Gauge32 Description: The maximum MSS, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MinMSS Scope: both ShortDescr: Minimum MSS Refer: RFC1191, Path MTU discovery Units: octets ProcType: Gauge32 Description: The minimum MSS, in octets. R/W: read-only ------------------------------------------------------------------------------ The following optional initial value objects are useful for conformance testing instruments on application progress and consumed network resources. ------------------------------------------------------------------------------ VariableName: SndInitial Scope: both RenameFrom: SndISS ShortDescr: Initial send sequence number. Refer: RFC793, Transmission Control Protocol ProcType: Unsigned32 Description: Initial send sequence number. Note that by definition tcpEStatsStackSndInitial never changes for a given connection. R/W: read-only ------------------------------------------------------------------------------ VariableName: RecInitial Scope: both RenameFrom: RecvISS ShortDescr: Initial receive sequence number Refer: RFC793, Transmission Control Protocol ProcType: Unsigned32 Description: Initial receive sequence number. Note that by definition tcpEStatsStackRecInitial never changes for a given connection. R/W: read-only ------------------------------------------------------------------------------ The following optional objects instrument the senders buffer usage, including any buffering in the application interface to TCP and the retransmit queue. All "buffer memory" instruments are assumed to include OS data structure overhead. ------------------------------------------------------------------------------ VariableName: CurRetxQueue Scope: both RenameFrom: CurRetranQueue ShortDescr: Current size of retransmit queue Units: octets ProcType: Gauge32 Description: The current number of octets of data occupying the retransmit queue. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxRetxQueue Scope: both RenameFrom: MaxRetranQueue ShortDescr: Maximum size of retransmit queue Units: octets ProcType: Gauge32 Description: The maximum number of octets of data occupying the retransmit queue. R/W: read-only ------------------------------------------------------------------------------ VariableName: CurAppWQueue Scope: both ShortDescr: Current size of application write queue Units: octets ProcType: Gauge32 Description: The current number of octets of application data buffered by TCP, pending first transmission, i.e. to the left of SND.NXT or SndMax. This data will generally be transmitted (and SND.NXT advanced to the left) as soon as there is available congestion window (cwnd) or receiver window (rwin). This is the amount of data readily available for transmission, without scheduling the application. TCP performance may suffer if there is insufficient queued write data. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxAppWQueue Scope: both ShortDescr: Maximum size of application write queue Units: octets ProcType: Gauge32 Description: The maximum number of octets of application data buffered by TCP, pending first transmission. This is the maximum value of tcpEStatsAppCurAppWQueue. This pair of objects can be used to determine if insufficient queued data is steady state (suggesting insufficient queue space) or transient (suggesting insufficient application performance or excessive CPU load or scheduler latency). R/W: read-only ------------------------------------------------------------------------------ VariableName: X_Sndbuf RenameFrom: Sndbuf Scope: Web100 ShortDescr: Socket sndbuf size ProcType: Gauge32 Description: The socket send buffer size is octets. Note that the meaning of this variable is implementation dependent. Particularly, it may or may not include the retransmit queue. R/W: read-only ------------------------------------------------------------------------------ The following objects instrument receiver window updates sent by the local receiver to the remote sender. These can be used to determine if the local receiver is exerting flow control back pressure on the remote sender. ------------------------------------------------------------------------------ VariableName: CurRwinSent Scope: both RenameFrom: CurrentRwinSent ShortDescr: current receiver window out Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Gauge32 Description: The most recent window advertisement sent, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxRwinSent Scope: both ShortDescr: maximum receiver window out Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Gauge32 Description: The maximum window advertisement sent, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MinRwinSent Scope: Web100 ShortDescr: minimum receiver window out Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Gauge32 Description: Not useful, deprecated, see: ZeroRwinSent R/W: read-only ------------------------------------------------------------------------------ VariableName: ZeroRwinSent Scope: RFC4898 ShortDescr: Number of ACKS sent with zero receive windows Refer: RFC793, Transmission Control Protocol ProcType: ZeroBasedCounter32 Description: The number of acknowledgments sent announcing a zero receive window, when the previously announced window was not zero. R/W: read-only ------------------------------------------------------------------------------ VariableName: LimRwin Scope: both ShortDescr: Bound on announced receiver window Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Unsigned32 Description: A control to set the maximum window advertisement which may be sent, in octets. R/W: read-write ------------------------------------------------------------------------------ VariableName: LimMSS Scope: RFC4898 ShortDescr: Bound on MSS Refer: RFC1191, Path MTU discovery Units: octets ProcType: Unsigned32 Description: A control to limit the maximum segment size in octets, that this TCP connection can use. R/W: read-write ------------------------------------------------------------------------------ The following optional objects are receiver side instruments of the path from the sender to the receiver. In general the receiver has less information about the state of the path, because the receiver does not have a robust mechanism to infer the sender's actions. ------------------------------------------------------------------------------ VariableName: DupAckEpisodes Scope: RFC4898 ShortDescr: Number of Duplicate Acks Sent when prior Ack was not duplicate Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of Duplicate Acks Sent when prior Ack was not duplicate. This is the number of times that a contiguous series of duplicate acknowledgments have been sent. This is an indication of the number of data segments lost or reordered on the path from the remote TCP endpoint to the near TCP endpoint. R/W: read-only ------------------------------------------------------------------------------ VariableName: RcvRTT RenameFrom: X_RcvRTT Scope: both ShortDescr: The receiver's estimate of the Path RTT ProcType: Gauge32 Description: The receiver's estimate of the Path RTT. Adaptive receiver window algorithms depend on the receiver to having a good estimate of the path RTT. R/W: read-only ------------------------------------------------------------------------------ VariableName: DupAcksOut Scope: both ShortDescr: Number of Duplicate Acks Sent Refer: RFC2581, TCP Congestion Control ProcType: ZeroBasedCounter32 Description: The number of duplicate ACKs sent. The ratio of the change in tcpEStatsPathDupAcksOut to the change in tcpEStatsPathDupAckEpisodes is an indication of reorder or recovery distance over some interval. R/W: read-only ------------------------------------------------------------------------------ VariableName: CERcvd RenameFrom: ECERcvd Scope: both ShortDescr: Received segments with Congestion Experienced bits Refer: RFC3168, The Addition of Explicit Congestion Notification (ECN) to IP ProcType: ZeroBasedCounter32 Description: The number of segments received with IP headers bearing Congestion Experienced (CE) markings. R/W: read-only ------------------------------------------------------------------------------ VariableName: ECESent Scope: RFC4898 ShortDescr: Number of times CE bits have set ECE Refer: RFC3168, The Addition of Explicit Congestion Notification (ECN) to IP ProcType: ZeroBasedCounter32 Description: Number of times the Echo Congestion Experienced (ECE) bit in the TCP header has been set (transitioned from 0 to 1), due to a Congestion Experienced (CE) marking on an IP header. Note that ECE can be set and reset only once per RTT, while CE can be set on many segments per RTT. R/W: read-only ------------------------------------------------------------------------------ VariableName: ECNNonceRcvd Scope: RFC4898 ShortDescr: Number of ECN Nonces received Refer: RFC3540, Robust Explicit Congestion Notification (ECN) Signaling with Nonces ProcType: ZeroBasedCounter32 Description: Number of ECN Nonces (NS bits) received. R/W: read-only ------------------------------------------------------------------------------ VariableName: CurReasmQueue Scope: both ShortDescr: Current size of reassembly queue Units: octets ProcType: Gauge32 Description: The current number of octets of sequence space spanned by the reassembly queue. This is generally the difference between rcv.nxt and the sequence number of the right most edge of the reassembly queue. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxReasmQueue Scope: both ShortDescr: Maximum size of reassembly queue ProcType: Gauge32 Description: The maximum value of tcpEStatsStackCurReasmQueue R/W: read-only ------------------------------------------------------------------------------ VariableName: CurAppRQueue Scope: both ShortDescr: Current size of application read queue Units: octets ProcType: Gauge32 Description: The current number of octets of application data that has been acknowledged by TCP but not yet delivered to the application. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxAppRQueue Scope: both ShortDescr: Maximum size of application read queue Units: octets ProcType: Gauge32 Description: The maximum number of octets of application data that has been acknowledged by TCP but not yet delivered to the application. R/W: read-only ------------------------------------------------------------------------------ VariableName: X_Rcvbuf RenameFrom: Rcvbuf Scope: Web100 ShortDescr: Socket rcvbuf size Units: octets ProcType: Gauge32 Description: The socket receive buffer size is octets. Note that the meaning of this variable is implementation dependent. In particular, it may or may not include the reassembly queue. R/W: read-only ------------------------------------------------------------------------------ VariableName: X_wnd_clamp Scope: Web100 ShortDescr: X_wnd_clamp ProcType: Gauge32 Description: Code dissection. R/W: read-only ------------------------------------------------------------------------------ VariableName: X_rcv_ssthresh Scope: Web100 ShortDescr: X_rcv_ssthresh ProcType: Gauge32 Description: Code dissection. R/W: read-only ------------------------------------------------------------------------------ VariableName: X_dbg1 Scope: Web100 ShortDescr: X_dbg1 ProcType: Gauge32 Description: Debugging R/W: read-only ------------------------------------------------------------------------------ VariableName: X_dbg2 Scope: Web100 ShortDescr: X_dbg2 ProcType: Gauge32 Description: Debugging R/W: read-only ------------------------------------------------------------------------------ VariableName: X_dbg3 Scope: Web100 ShortDescr: X_dbg3 ProcType: Gauge32 Description: Debugging R/W: read-only ------------------------------------------------------------------------------ VariableName: X_dbg4 Scope: Web100 ShortDescr: X_dbg4 ProcType: Gauge32 Description: Debugging R/W: read-only ------------------------------------------------------------------------------ The following objects instrument receiver window updates from the far end-system to determine if the remote receiver has sufficient buffer space or is exerting flow-control back pressure on the local sender. ------------------------------------------------------------------------------ VariableName: CurRwinRcvd Scope: both RenameFrom: CurrentRwinRcvd ShortDescr: Current Receiver Window Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Gauge32 Description: The most recent window advertisement received, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MaxRwinRcvd Scope: Web100 ShortDescr: Maximum Receiver Window Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Gauge32 Description: The maximum window advertisement received, in octets. R/W: read-only ------------------------------------------------------------------------------ VariableName: MinRwinRcvd Scope: Web100 ShortDescr: Minimum Receiver Window Refer: RFC793, Transmission Control Protocol Units: octets ProcType: Gauge32 Description: Not uesful, deprecated, see ZeroRwinRcvd R/W: read-only ------------------------------------------------------------------------------ VariableName: ZeroRwinRcvd Scope: RFC4898 ShortDescr: Minimum Receiver Window Refer: RFC793, Transmission Control Protocol ProcType: ZeroBasedCounter32 Description: The number of acknowledgments received announcing a zero receive window, when the previously announced window was not zero. R/W: read-only ------------------------------------------------------------------------------