Network Diagnostic Tool (NDT) BigQuery Schema

NDT is a single stream performance measurement of a connection’s capacity for “bulk transport” (as defined in IETF’s RFC 3148. Therefore it would be most precise to say that M-Lab’s NDT test measures “single stream performance” or “bulk transport capacity”. NDT reports upload and download speeds and attempts to determine what problems limit speeds.

NDT BigQuery Views

  • measurement-lab.ndt.recommended
    • A subset view of all NDT upload and download tests from measurement-lab.ndt.web100 where:
      • TCP end state is sensible
      • Test duration was between 9 and 60 seconds
    • except:
      • Internal M-Lab end-to-end monitoring tests
      • Tests not marked as blacklisted
  • measurement-lab.ndt.downloads
    • A subset view of all NDT download tests from measurement-lab.ndt.recommended where:
      • At least 8 KB of data was transferred
      • Test duration was between 9 and 60 seconds
      • Congestion was detected
  • measurement-lab.ndt.uploads
    • A subset view of all NDT upload tests from measurement-lab.ndt.recommended where:
      • A sensible total number of bytes was received (8192)
  • measurement-lab.ndt.web100
    • A root view that all other views in the ndt dataset are derived from.

Common Metrics

Commonly reported metrics such as upload or download speed are calculated from individual fields saved by the Network Diagnostic Tool. See our page on calculating common metrics from NDT data for more information.

Equivalent BigQuery and Web100 Field Types

NDT data collected by M-Lab has historically used the Web100 Linux kernel patch to provides access to a rich set of TCP information for each NDT test. The file tcp-kis.txt defines each Web100 variable with a specific SNMP type. The table below shows how to map each SNMP type to a BigQuery type.

BigQuery Type Corresponding SNMP Type
integer Integer32, Integer, INTEGER, Gauge32, ZeroBasedCounter32, Unsigned32, Unsigned16, Counter32, ZeroBasedCounter64
string Ip_Address
bool TruthValue

Transition from Web100 to TCP_INFO Kernel Instrumentation

In 2019, M-Lab will transition its hosted experiments to use the netlink socket and TCP_INFO kernel instrumentation, replacing our reliance on Web100.

Blacklist Flags Field

The field blacklist_flags was used to mark test affected by the “switch discard issue” identified in 2015-2016. M-Lab NDT data from 2010-01-01 to 2015-10-02 was marked using this field. M-Lab may use the field for other use cases in the future for tests potentially impacted by site configuration issues, or otherwise communicate potentially relevant information about the state of the platform at the time of the test.

Since the NDT v3.1 schema, a sub-record has been present in NDT views, anomalies, which contains an equivalent field, anomalies.blacklist_flags.

Currently, the following values are present in NDT data from 2010-01-01 to 2015-10-02 in these fields:

Field Name Value Description
blacklist_flags or anomalies.blacklist_flags 0 or NULL unaffected tests
  1 tests affected by switch discards
  2 tests not shown to be unaffected by switch discards

NDT Schema - measurement-lab.ndt.recommended

Field name Type Description
partition_date date The day (in UTC) in which the data was loaded. For more precise datetime or timestamp of each test, use the field web100_log_entry.log_time
test_id string ID of the test. It represents the filename of the log that contains the data generated during the test (e.g. 20090819T02:01:04.507508000Z_189.6.232.77:3859.c2s_snaplog.gz).
task_filename string The raw data file in Google Cloud Storage from which the test row was parsed.
parse_time timestamp The timestamp of when test data was parsed into BigQuery from Google Cloud Storage.
parser_version string A link to the tagged version of the M-Lab ETL parser which processed the test row.
log_time timestamp The timestamp of when test log was created (in seconds since Unix epoch). This is derived from the “Date/Time” field in the .meta file (Prefer the web100_log_entry.log_time field, as it is more reliable).
blacklist_flags integer Deprecated field formerly used to store blacklist flags. Superceded by anomalies.blacklist_flags.
anomalies record A sub-record section containing anomalies fields.
anomalies.no_meta boolean If a test record did not contain a metadata file, this field is set to 1.
anomalies.snaplog_error boolean If there are errors in the snaplogs for a test, this field is set to 1.
anomalies.num_snaps integer A count of the number of snaplogs captured during a given test.
anomalies.blacklist_flags integer Used to mark test results that could be impacted by site configuration issues, or otherwise to communicate potentially relevant information about the state of the platform at the time of the test.
connection_spec record Sub-record section containing fields describing the client which initiated a test and the M-Lab server through which the test was conducted.
connection_spec.client_af integer Address family of the client’s IP address. (This field is optional.)
AF_INET (IPv4) = 2
AF_INET6 (IPv6) = 10
connection_spec.client_application string Client application that ran the test. (This field is optional.)
connection_spec.client_browser string Client’s browser. (This field is optional.)
connection_spec.client_hostname string Client’s hostname. (This field is optional.)
connection_spec.client_ip string IP address of the user’s client. (This field is optional. It’s preferable to use web100_log_entry.connection_spec.remote_ip.)
connection_spec.client_kernel_version string Client’s kernel version. (This field is optional.)
connection_spec.client_os string Client’s operating system. (This field is optional.)
connection_spec.client_version string Client’s version. (This field is optional.)
connection_spec.data_direction integer Direction of the data sent during the test:
CLIENT_TO_SERVER (upload) = 0
SERVER_TO_CLIENT (download) = 1
connection_spec.server_af integer Address family of the server’s IP address. (This field is optional. It’s preferable to use web100_log_entry.connection_spec.local_af.)
AF_INET (IPv4) = 2
AF_INET6 (IPv6) = 10
connection_spec.server_hostname string The hostname of the M-Lab server that received this test. (This field is optional.)
connection_spec.server_ip string The M-Lab server’s IP address. (This field is optional. It’s preferable to use web100_log_entry.connection_spec.local_ip.)
connection_spec.server_kernel_version string The M-Lab server’s kernel version. (This field is optional.)
connection_spec.tls boolean  
connection_spec.websockets boolean  
connection_spec.client_geolocation record Sub-record section containing geolocation annotations for the client that initiated the test. Geolocation fields extracted from open dataset created by MaxMind and available at (These fields are optional.)
client_geolocation.area_code integer string  
client_geolocation.continent_code string  
client_geolocation.country_code string  
client_geolocation.country_code3 string  
client_geolocation.country_name string  
client_geolocation.latitude float  
client_geolocation.longitude float  
client_geolocation.metro_code integer  
client_geolocation.postal_code string  
client_geolocation.region string  
client_geolocation.radius string  
connection_spec.server_geolocation record Sub-record section containing geolocation annotations for the M-Lab server that received the test. Geolocation fields extracted from open dataset created by MaxMind and available at (These fields are optional.)
server_geolocation.area_code integer string  
server_geolocation.continent_code string  
server_geolocation.country_code string  
server_geolocation.country_code3 string  
server_geolocation.country_name string  
server_geolocation.latitude float  
server_geolocation.longitude float  
server_geolocation.metro_code integer  
server_geolocation.postal_code string  
server_geolocation.region string  
server_geolocation.radius string record Sub-record section containing fields about the client network from which the test was conducted. string The Autonomous System Number (ASN) of the client network where this test originated. record Sub-record section containing fields about the server network through which the test was conducted. string The IATA airport code nearest to the M-Lab server through which this test was conducted. string The Autonomous System Number (ASN) of the server network through which this test was conducted.
web100_log_entry record Sub-record section containing the web100 variables collected during the test. See tcp-kis.txt for more information about these fields.
web100_log_entry.log_time integer  
web100_log_entry.version string  
web100_log_entry.connection_spec.local_af integer IPv4 = 0
IPv6 = 1
web100_log_entry.connection_spec.local_ip string  
web100_log_entry.connection_spec.local_port integer  
web100_log_entry.connection_spec.remote_ip string  
web100_log_entry.connection_spec.remote_port integer  
web100_log_entry.snap record  
web100_log_entry.snap.AbruptTimeouts integer  
web100_log_entry.snap.ActiveOpen integer  
web100_log_entry.snap.CERcvd integer  
web100_log_entry.snap.CongAvoid integer  
web100_log_entry.snap.CongOverCount integer  
web100_log_entry.snap.CongSignals integer  
web100_log_entry.snap.CountRTT integer  
web100_log_entry.snap.CurAppRQueue integer  
web100_log_entry.snap.CurAppWQueue integer  
web100_log_entry.snap.CurCwnd integer  
web100_log_entry.snap.CurMSS integer  
web100_log_entry.snap.CurRTO integer  
web100_log_entry.snap.CurReasmQueue integer  
web100_log_entry.snap.CurRetxQueue integer  
web100_log_entry.snap.CurRwinRcvd integer  
web100_log_entry.snap.CurRwinSent integer  
web100_log_entry.snap.CurSsthresh integer  
web100_log_entry.snap.CurTimeoutCount integer  
web100_log_entry.snap.DSACKDups integer  
web100_log_entry.snap.DataSegsIn integer  
web100_log_entry.snap.DataSegsOut integer  
web100_log_entry.snap.DupAcksIn integer  
web100_log_entry.snap.DupAcksOut integer  
web100_log_entry.snap.Duration integer  
web100_log_entry.snap.ECN integer  
web100_log_entry.snap.FastRetran integer  
web100_log_entry.snap.HCDataOctetsIn integer  
web100_log_entry.snap.HCDataOctetsOut integer  
web100_log_entry.snap.HCThruOctetsAcked integer  
web100_log_entry.snap.HCThruOctetsReceived integer  
web100_log_entry.snap.LimCwnd integer  
web100_log_entry.snap.LimRwin integer  
web100_log_entry.snap.LocalAddress string  
web100_log_entry.snap.LocalAddressType integer  
web100_log_entry.snap.LocalPort integer  
web100_log_entry.snap.MSSRcvd integer  
web100_log_entry.snap.MaxAppRQueue integer  
web100_log_entry.snap.MaxAppWQueue integer  
web100_log_entry.snap.MaxMSS integer  
web100_log_entry.snap.MaxRTO integer  
web100_log_entry.snap.MaxRTT integer  
web100_log_entry.snap.MaxReasmQueue integer  
web100_log_entry.snap.MaxRetxQueue integer  
web100_log_entry.snap.MaxRwinRcvd integer  
web100_log_entry.snap.MaxRwinSent integer  
web100_log_entry.snap.MaxSsCwnd integer  
web100_log_entry.snap.MaxSsthresh integer  
web100_log_entry.snap.MinMSS integer  
web100_log_entry.snap.MinRTO integer  
web100_log_entry.snap.MinRTT integer  
web100_log_entry.snap.MinRwinRcvd integer  
web100_log_entry.snap.MinRwinSent integer  
web100_log_entry.snap.MinSsthresh integer  
web100_log_entry.snap.Nagle integer  
web100_log_entry.snap.NonRecovDA integer  
web100_log_entry.snap.OctetsRetrans integer  
web100_log_entry.snap.OtherReductions integer  
web100_log_entry.snap.PostCongCountRTT integer  
web100_log_entry.snap.PostCongSumRTT integer  
web100_log_entry.snap.PreCongSumCwnd integer  
web100_log_entry.snap.PreCongSumRTT integer  
web100_log_entry.snap.QuenchRcvd integer  
web100_log_entry.snap.RTTVar integer  
web100_log_entry.snap.RcvNxt integer  
web100_log_entry.snap.RcvRTT integer  
web100_log_entry.snap.RcvWindScale integer  
web100_log_entry.snap.RecInitial integer  
web100_log_entry.snap.RemAddress string  
web100_log_entry.snap.RemPort integer  
web100_log_entry.snap.RetranThresh integer  
web100_log_entry.snap.SACK integer  
web100_log_entry.snap.SACKBlocksRcvd integer  
web100_log_entry.snap.SACKsRcvd integer  
web100_log_entry.snap.SampleRTT integer  
web100_log_entry.snap.SegsIn integer  
web100_log_entry.snap.SegsOut integer  
web100_log_entry.snap.SegsRetrans integer  
web100_log_entry.snap.SendStall integer  
web100_log_entry.snap.SlowStart integer  
web100_log_entry.snap.SmoothedRTT integer  
web100_log_entry.snap.SndInitial integer  
web100_log_entry.snap.SndLimBytesCwnd integer  
web100_log_entry.snap.SndLimBytesRwin integer  
web100_log_entry.snap.SndLimBytesSender integer  
web100_log_entry.snap.SndLimTimeCwnd integer  
web100_log_entry.snap.SndLimTimeRwin integer  
web100_log_entry.snap.SndLimTimeSnd integer  
web100_log_entry.snap.SndLimTransCwnd integer  
web100_log_entry.snap.SndLimTransRwin integer  
web100_log_entry.snap.SndLimTransSnd integer  
web100_log_entry.snap.SndMax integer  
web100_log_entry.snap.SndNxt integer  
web100_log_entry.snap.SndUna integer  
web100_log_entry.snap.SndWindScale integer  
web100_log_entry.snap.SpuriousFrDetected integer  
web100_log_entry.snap.StartTimeStamp integer  
web100_log_entry.snap.StartTimeUsec integer  
web100_log_entry.snap.State integer  
web100_log_entry.snap.SubsequentTimeouts integer  
web100_log_entry.snap.SumRTT integer  
web100_log_entry.snap.TimeStamps integer  
web100_log_entry.snap.Timeouts integer  
web100_log_entry.snap.WinScaleRcvd integer  
web100_log_entry.snap.WinScaleSent integer  
web100_log_entry.snap.X_OtherReductionsCM integer  
web100_log_entry.snap.X_OtherReductionsCV integer  
web100_log_entry.snap.X_Rcvbuf integer  
web100_log_entry.snap.X_Sndbuf integer  
web100_log_entry.snap.X_dbg1 integer  
web100_log_entry.snap.X_dbg2 integer  
web100_log_entry.snap.X_dbg3 integer  
web100_log_entry.snap.X_dbg4 integer  
web100_log_entry.snap.X_rcv_ssthresh integer  
web100_log_entry.snap.X_wnd_clamp integer  
web100_log_entry.deltas record Placeholder subrecord where M-Lab may add intermediate snaplog changes to web100_log_entry fields that take place over the course of each test. Currenly, only the final web100_log_entry.snap field values are stored in the above record section of the schema.
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