RTDelay_Active_IP-UDP-Periodic_RFC8912sec4_Seconds_95Percentile All section numbers below refer to RFC 8912  4.1. Summary    This category includes multiple indexes to the Registry Entries: the element ID and Metric Name. 4.1.1. ID (Identifier)    1 4.1.2. Name    RTDelay_Active_IP-UDP-Periodic_RFC8912sec4_Seconds_95Percentile 4.1.3. URI    URL: https://www.iana.org/assignments/performance-metrics/RTDelay_Active_IP-UDP-Periodic_RFC8912sec4_Seconds_95Percentile 4.1.4. Description    RTDelay:     This metric assesses the delay of a stream of packets exchanged between two hosts (which      are the two measurement points). The output is the round-trip delay for all successfully      exchanged packets expressed as the 95th percentile of their conditional delay distribution. 4.1.5. Change Controller    IETF 4.1.6. Version (of Registry Format)    1.0 4.2. Metric Definition    This category includes columns to prompt the entry of all necessary details related to the metric     definition, including the RFC reference and values of input factors, called "Fixed Parameters". 4.2.1. Reference Definition    Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay Metric for IPPM", RFC 2681,     DOI 10.17487/RFC2681, September 1999, . [RFC2681]    Section 2.4 of [RFC2681] provides the reference definition of the singleton (single value)     round-trip delay metric. Section 3.4 of [RFC2681] provides the reference definition expanded to     cover a multi-singleton sample. Note that terms such as "singleton" and "sample" are defined in     Section 11 of [RFC2330].    Note that although the definition of round-trip delay between the Source (Src) and the Destination     (Dst) as provided in Section 2.4 of [RFC2681] is directionally ambiguous in the text, this metric     tightens the definition further to recognize that the host in the Src Role will send the first     packet to the host in the Dst Role and will ultimately receive the corresponding return packet     from the Dst (when neither is lost).    Finally, note that the variable "dT" is used in [RFC2681] to refer to the value of round-trip     delay in metric definitions and methods. The variable "dT" has been reused in other IPPM literature     to refer to different quantities and cannot be used as a global variable name.    Both Delay and Loss metrics employ a maximum waiting time for received packets, so the count of     lost packets to total packets sent is the basis for the loss ratio calculation as per Section 6.1     of [RFC6673]. 4.2.2. Fixed Parameters    Type-P as defined in Section 13 of [RFC2330]:    IPv4 header values:       DSCP:  Set to 0       TTL:   Set to 255       Protocol:  Set to 17 (UDP)    IPv6 header values:       DSCP:  Set to 0       Hop Count:  Set to 255       Next Header:  Set to 17 (UDP)       Flow Label:  Set to 0       Extension Headers:  None    UDP header values:              Checksum:  The checksum MUST be calculated and the non-zero checksum included in the header           UDP Payload:         Total of 100 bytes    Other measurement Parameters:    Tmax:       A loss threshold waiting time with value 3.0, expressed in units of seconds, as a positive        value of type decimal64 with fraction digits = 4 (see Section 9.3 of [RFC6020]) and with a        resolution of 0.0001 seconds (0.1 ms), with lossless conversion to/from the 32-bit NTP        timestamp as per Section 6 of [RFC5905]. 4.3. Method of Measurement    This category includes columns for references to relevant sections of the RFC(s) and     any supplemental information needed to ensure an unambiguous method for implementations. 4.3.1. Reference Methods    The methodology for this metric (equivalent to Type-P-Round-trip- Delay and     Type-P-Round-trip-Delay-Poisson-Stream) is defined as in Section 2.6 of [RFC2681]     (for singletons) and Section 3.6 of [RFC2681] (for samples) using the Type-P and     Tmax defined in the Fixed Parameters column. However, the Periodic stream will be     generated according to [RFC3432].    The reference method distinguishes between long-delayed packets and lost packets by     implementing a maximum waiting time for packet arrival. Tmax is the waiting time used     as the threshold to declare a packet lost. Lost packets SHALL be designated as having     undefined delay and counted for the RTLoss metric.    The calculations on the delay (RTT) SHALL be performed on the conditional distribution,     conditioned on successful packet arrival within Tmax. Also, when all packet delays are     stored, the process that calculates the RTT value MUST enforce the Tmax threshold on     stored values before calculations. See Section 4.1 of [RFC3393] for details on the     conditional distribution to exclude undefined values of delay, and see Section 5 of     [RFC6703] for background on this analysis choice.    The reference method requires some way to distinguish between different packets in a     stream to establish correspondence between sending times and receiving times for each     successfully arriving packet. Sequence numbers or other send-order identification MUST     be retained at the Src or included with each packet to disambiguate packet reordering     if it occurs.    If a standard measurement protocol is employed, then the measurement process will determine     the sequence numbers or timestamps applied to test packets after the Fixed and Runtime     Parameters are passed to that process. The chosen measurement protocol will dictate the     format of sequence numbers and timestamps, if they are conveyed in the packet payload.    Refer to Section 4.4 of [RFC6673] for an expanded discussion of the instruction to     "send a Type-P packet back to the Src as quickly as possible" in Section 2.6 of [RFC2681].     Section 8 of [RFC6673] presents additional requirements that MUST be included in the Method     of Measurement for this metric. 4.3.2. Packet Stream Generation    This section provides details regarding packet traffic, which is used as the basis for     measurement. In IPPM Metrics, this is called the "stream"; this stream can easily be     described by providing the list of stream Parameters.    Section 3 of [RFC3432] prescribes the method for generating Periodic streams using     associated Parameters.    incT:         The nominal duration of the inter-packet interval, first bit to first bit, with value        0.0200, expressed in units of seconds, as a positive value of type decimal64 with        fraction digits = 4 (see Section 9.3 of [RFC6020]) and with a resolution of 0.0001        seconds (0.1 ms).    dT:       The duration of the interval for allowed sample start times, with value 1.0, expressed        in units of seconds, as a positive value of type decimal64 with fraction digits = 4 (see        Section 9.3 of [RFC6020]) and with a resolution of 0.0001 seconds (0.1 ms).    Note: An initiation process with a number of control exchanges resulting in unpredictable     start times (within a time interval) may be sufficient to avoid synchronization of     periodic streams and is a valid replacement for selecting a start time at random from     a fixed interval.    The T0 Parameter will be reported as a measured Parameter. Parameters incT and dT are     Fixed Parameters. 4.3.3. Traffic Filtering (Observation) Details    N/A 4.3.4. Sampling Distribution      N/A 4.3.5. Runtime Parameters and Data Format    Runtime Parameters are input factors that must be determined, configured into the measurement     system, and reported with the results for the context to be complete.    Src:       The IP address of the host in the Src Role (format ipv4‑address-no-zone value for        IPv4 or ipv6-address-no-zone value for IPv6; see Section 4 of [RFC6991]).    Dst:       The IP address of the host in the Dst Role (format ipv4‑address-no-zone value for        IPv4 or ipv6-address-no-zone value for IPv6; see Section 4 of [RFC6991]).    T0:       A time, the start of a measurement interval (format "date‑time" as specified in        Section 5.6 of [RFC3339]; see also "date‑and‑time" in Section 3 of [RFC6991]). The        UTC Time Zone is required by Section 6.1 of [RFC2330]. When T0 is "all-zeros", a start        time is unspecified and Tf is to be interpreted as the duration of the measurement        interval. The start time is controlled through other means.    Tf:       A time, the end of a measurement interval (format "date‑time" as specified in        Section 5.6 of [RFC3339]; see also "date‑and‑time" in Section 3 of [RFC6991]). The        UTC Time Zone is required by Section 6.1 of [RFC2330]. When T0 is "all-zeros", an        ending time and date is ignored and Tf is interpreted as the duration of the        measurement interval. 4.3.6. Roles    Src:       Launches each packet and waits for return transmissions from the Dst.    Dst:       Waits for each packet from the Src and sends a return packet to the Src. 4.4. Output    This category specifies all details of the output of measurements using the metric. 4.4.1. Type    Percentile: For the conditional distribution of all packets with a valid value     of round-trip delay (undefined delays are excluded), this is a single value     corresponding to the 95th percentile, as follows:    See Section 4.1 of [RFC3393] for details on the conditional distribution to exclude     undefined values of delay, and see Section 5 of [RFC6703] for background on this     analysis choice.    The percentile = 95, meaning that the reported delay, "95Percentile", is the smallest     value of round-trip delay for which the Empirical Distribution Function,     EDF(95Percentile), is greater than or equal to 95% of the singleton round-trip delay     values in the conditional distribution. See Section 11.3 of [RFC2330] for the definition     of the percentile statistic using the EDF. 4.4.2. Reference Definition    For all outputs:    T0:       The start of a measurement interval (format "date‑time" as specified in        Section 5.6 of [RFC3339]; see also "date‑and‑time" in Section 3 of [RFC6991]).        The UTC Time Zone is required by Section 6.1 of [RFC2330].    Tf:       The end of a measurement interval (format "date‑time" as specified in        Section 5.6 of [RFC3339]; see also "date‑and‑time" in Section 3 of [RFC6991]).        The UTC Time Zone is required by Section 6.1 of [RFC2330].    TotalPkts:       The count of packets sent by the Src to the Dst during the measurement interval.    95Percentile:       The time value of the result is expressed in units of seconds, as a positive value        of type decimal64 with fraction digits = 9 (see Section 9.3 of [RFC6020]) with a        resolution of 0.000000001 seconds (1.0 ns). 4.4.3. Metric Units    The 95th percentile of round-trip delay is expressed in seconds. 4.4.4. Calibration    Section 3.7.3 of [RFC7679] provides a means to quantify the systematic and random errors     of a time measurement. Calibration in-situ could be enabled with an internal loopback at     the Source host that includes as much of the measurement system as possible, performs address     manipulation as needed, and provides some form of isolation (e.g., deterministic delay) to     avoid send-receive interface contention. Some portion of the random and systematic error can     be characterized in this way.    When a measurement controller requests a calibration measurement, the loopback is applied and     the result is output in the same format as a normal measurement, with an additional indication     that it is a calibration result.    Both internal loopback calibration and clock synchronization can be used to estimate the available     accuracy of the Output Metric Units. For example, repeated loopback delay measurements will     reveal the portion of the output result resolution that is the result of system noise and is     thus inaccurate. 4.5. Administrative Items 4.5.1. Status    Current 4.5.2. Requester    RFC 8912 4.5.3. Revision    1.0 4.5.4. Revision Date    2021-11-17 4.6. Comments and Remarks    None