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RFC 5388

Proposed STD
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Information Model and XML Data Model for Traceroute Measurements

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Network Working Group                                       S. Niccolini
Request for Comments: 5388                                 S. Tartarelli
Category: Standards Track                                     J. Quittek
                                                                T. Dietz
                                                                     NEC
                                                                M. Swany
                                                                    UDel
                                                           December 2008


    Information Model and XML Data Model for Traceroute Measurements

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (c) 2008 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (http://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Abstract

   This document describes a standard way to store the configuration and
   the results of traceroute measurements.  This document first
   describes the terminology used in this document and the traceroute
   tool itself; afterwards, the common information model is defined,
   dividing the information elements into two semantically separated
   groups (configuration elements and results elements).  Moreover, an
   additional element is defined to relate configuration elements and
   results elements by means of a common unique identifier.  On the
   basis of the information model, a data model based on XML is defined
   to store the results of traceroute measurements.

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Table of Contents

   1. Introduction ....................................................3
   2. Terminology Used in This Document ...............................3
   3. The Traceroute Tool and Its Operations ..........................4
   4. Results of Traceroute Measurements ..............................5
   5. Information Model for Traceroute Measurements ...................5
      5.1. Data Types .................................................6
      5.2. Information Elements .......................................7
           5.2.1. Relationships between the Information Elements ......7
           5.2.2. Configuration Information Elements .................12
           5.2.3. Results Information Elements .......................17
           5.2.4. Information Element Correlating
                  Configuration and Results ..........................21
           5.2.5. Information Elements to Compare Traceroute
                  Measurement Results ................................22
   6. Data Model for Storing Traceroute Measurements .................23
   7. XML Schema for Traceroute Measurements .........................24
   8. Security Considerations ........................................38
      8.1. Conducting Traceroute Measurements ........................39
      8.2. Securing Traceroute Measurement Information ...............39
   9. IANA Considerations ............................................40
   10. References ....................................................40
      10.1. Normative References .....................................40
      10.2. Informative References ...................................41
   Appendix A. Traceroute Default Configuration Parameters ...........43
      A.1. Alternative Traceroute Implementations ....................46
   Appendix B. Known Problems with Traceroute ........................47
      B.1. Compatibility between Traceroute Measurement Results
           and IPPM Metrics ..........................................47
   Appendix C. Differences to DISMAN-TRACEROUTE-MIB ..................47
      C.1. Scope .....................................................48
      C.2. Naming ....................................................49
      C.3. Semantics .................................................49
      C.4. Additional Information Elements ...........................50
   Appendix D. Traceroute Examples with XML Representation ...........50

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1.  Introduction

   Traceroutes are used by lots of measurement efforts, either as
   independent measurements or as a means of getting path information to
   support other measurement efforts.  That is why there is the need to
   standardize the way the configuration and the results of traceroute
   measurements are stored.  The standard metrics defined by the IPPM
   group in matters of delay, connectivity, and losses do not apply to
   the metrics returned by the traceroute tool.  Therefore, in order to
   compare results of traceroute measurements, the only possibility is
   to add to the stored results a specification of the operating system
   as well as the name and version for the traceroute tool used.  This
   document, in order to store results of traceroute measurements and
   allow comparison of them, defines a standard way to store them using
   an XML schema.

   The document is organized as follows: Section 2 defines the
   terminology used in this document; Section 3 describes the traceroute
   tool; Section 4 describes the results of a traceroute measurement as
   displayed to the screen from which the traceroute tool was launched;
   Section 5 and Section 6, respectively, describe the information model
   and data model for storing configuration and results of the
   traceroute measurements; Section 7 contains the XML schema to be used
   as a template for storing and/or exchanging traceroute measurement
   information; the document ends with security considerations and IANA
   considerations in Section 8 and Section 9 respectively.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Terminology Used in This Document

   The terminology used in this document is defined as follows:

   o  traceroute tool: a software tool for network diagnostic that
      behaves as described in Section 3;

   o  traceroute measurement: an instance of the traceroute tool
      launched, with specific configuration parameters (traceroute
      measurement configuration parameters), from a specific host
      (initiator of the traceroute measurement) giving as output
      specific traceroute measurement results;

   o  traceroute probe: one of many IP packets sent out by the
      traceroute tool during a traceroute measurement;

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   o  traceroute measurement configuration parameters: the configuration
      parameters of a traceroute measurement;

   o  traceroute measurement results: the results of a traceroute
      measurement;

   o  traceroute measurement information: both the results and the
      configuration parameters of a traceroute measurement;

   o  traceroute measurement path: a sequence of hosts transited in
      order by traceroute probes during a traceroute measurement.

3.  The Traceroute Tool and Its Operations

   Traceroute is a network diagnostic tool used to determine the hop-by-
   hop path from a source to a destination and the Round Trip Time (RTT)
   from the source to each hop.  Traceroute can be therefore used to
   discover some information (hop counts, delays, etc.) about the path
   between the initiator of the traceroute measurement and other hosts.

   Typically, the traceroute tool attempts to discover the path to a
   destination by sending UDP probes with specific time-to-live (TTL)
   values in the IP packet header and trying to elicit an ICMP
   TIME_EXCEEDED response from each gateway along the path to some host.

   In more detail, a first set of probes with TTL equal to 1 is sent by
   the traceroute tool from the host initiating the traceroute
   measurement (some tool implementations allow setting the initial TTL
   to a value equal to "n" different from 1, so that the first "n-1"
   hops are skipped and the first hop that will be traced is the "n-th"
   in the path).  Upon receiving a probe, the first hop host decreases
   the TTL value (by one or more).  By observing a TTL value equal to
   zero, the host rejects the probe and typically returns an ICMP
   message with a TIME_EXCEEDED value.  The traceroute tool can
   therefore derive the IP address of the first hop from the header of
   the ICMP message and evaluate the RTT between the host initiating the
   traceroute measurement and the first hop.  The next hops are
   discovered following the same procedure, taking care to increase at
   each step the TTL value of the probes by one.  The TTL value is
   increased until either an ICMP PORT_UNREACHABLE message is received,
   meaning that the destination host has been reached, or the maximum
   configured number of hops has been hit.

   Some implementations use ICMP Echoes, instead of UDP datagrams.
   However, many routers do not return ICMP messages about ICMP
   messages, i.e., no ICMP TIME_EXCEEDED is returned for an ICMP Echo.

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   Therefore, this document recommends to base implementations on UDP
   datagrams.  Considerations on TCP-based implementations of the
   traceroute tool are reported in Appendix A.1.

4.  Results of Traceroute Measurements

   The following list reports the information fields provided as results
   by all traceroute tool implementations considered.  The order in
   which they are reported here is not relevant and changes in different
   implementations.  For each hop, the following information is
   reported:

   o  the hop index;

   o  the host symbolic address, provided that at least one of the
      probes received a response, the symbolic address could be resolved
      at the corresponding host, and the option to display only
      numerical addresses was not set;

   o  the host IP address, provided that at least one of the probes
      received a response;

   o  the RTT for each response to a probe.

   Depending on the traceroute tool implementation, additional
   information might be displayed in the output (for instance, MPLS-
   related information).

   It might happen that some probes do not receive a response within the
   configured timeout (for instance, if the probe is filtered out by a
   firewall).  In this case, an "*" is displayed in place of the RTT.
   The information model reflects this using a string with the value of
   "RoundTripTimeNotAvailable", meaning either the probe was lost
   because of a timeout or it was not possible to transmit a probe.  It
   may also happen that some implementations print the same line
   multiple times when a router decreases the TTL by more than one, thus
   looking like multiple hops.  The information model is not impacted by
   this since each line is handled separately; it is left to the
   applications handling the XML file how to deal with it.  Moreover,
   for delays below 1 ms, some implementations report 0 ms (e.g., UNIX
   and LINUX), while WINDOWS reports "< 1 ms".

5.  Information Model for Traceroute Measurements

   The information model is composed of information elements; for
   defining these information elements, a template is used.  Such
   template is specified in the list below:

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   o  name - A unique and meaningful name for the information element.
      The preferred spelling for the name is to use mixed case if the
      name is compound, with an initial lower-case letter, e.g.,
      "sourceIpAddress".

   o  description - The semantics of this information element.

   o  dataType - One of the types listed in Section 5.1 of this document
      or in an extension of the information model.  The type space for
      attributes is constrained to facilitate implementation.

   o  units - If the element is a measure of some kind, the units
      identify what the measure is.

5.1.  Data Types

   This section describes the set of basic valid data types of the
   information model.

   o  string - The type "string" represents a finite-length string of
      valid characters from the Unicode character encoding set.  Unicode
      allows for ASCII and many other international character sets to be
      used.  It is expected that strings will be encoded in UTF-8
      format, which is identical in encoding for US-ASCII characters but
      which also accommodates other Unicode multi-byte characters.

   o  string255 - Same type as "string" but with the restriction of 255
      characters.

   o  inetAddressType - The type "inetAddressType" represents a type of
      Internet address.  The allowed values are imported from [RFC4001]
      (where the intent was to import only some of the values);
      additional allowed values are "asnumber" and "noSpecification".

   o  inetAddress - The type "inetAddress" denotes a generic Internet
      address.  The allowed values are imported from [RFC4001] (the
      values imported are unknown, ipv4, ipv6, and dns), while non-
      global IPv4/IPv6 addresses (e.g., ipv4z and ipv6z) are excluded;
      an additional allowed value is the AS number, indicated as the
      actual number plus the indication of how the mapping from IP
      address to AS number was performed.  "Unknown" is used to indicate
      an IP address that is not in one of the formats defined.

   o  ipASNumberMappingType - The type "ipASNumberMappingType"
      represents a type of mapping from IP to AS number, it indicates
      the method that was used to do get the mapping (allowed values are
      "bgptables", "routingregistries", "nslookup", "others" or
      "unknown").

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   o  boolean - The type "boolean" represents a boolean value according
      to XML standards [W3C.REC-xmlschema-2-20041028].

   o  unsignedInt - The type "unsignedInt" represents a value in the
      range (0..4294967295).

   o  unsignedShort - The type "unsignedShort" represents a value in the
      range (0..65535).

   o  unsignedByte - The type "unsignedByte" represents a value in the
      range (0..255).

   o  u8nonzero - The type "u8nonzero" represents a value in the range
      (1..255).

   o  probesType - The type "probesType" represents a way of indicating
      the protocol used for the traceroute probes.  Values defined in
      this document are UDP, TCP, and ICMP.

   o  operationResponseStatus - The type "operationResponseStatus" is
      used to report the result of an operation.  The allowed values are
      imported from [RFC4560].

   o  dateTime - The type "dateTime" represents a date-time
      specification according to XML standards
      [W3C.REC-xmlschema-2-20041028] but is restricted to the values
      defined in [RFC3339].

5.2.  Information Elements

   This section describes the elements related to the storing of a
   traceroute measurement.  The elements are grouped in two groups
   (configuration and results) according to their semantics.  In order
   to relate configuration and results elements by means of a common
   unique identifier, an additional element is defined belonging to both
   groups.

5.2.1.  Relationships between the Information Elements

   Every traceroute measurement is represented by an instance of the
   "traceRoute" element.  This class provides a standardized
   representation for traceroute measurement data.  The "traceroute"
   element is an element that can be composed of (depending on the
   nature of the traceroute measurement):

   o  1 optional "RequestMetadata" element;

   o  0..2147483647 "Measurement" elements.

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   Each "Measurement" element contains:

   o  1 optional "MeasurementMetadata" element;

   o  0..2147483647 "MeasurementResult" elements.

   The "RequestMetadata" element can be used for specifying parameters
   of a traceroute measurement to be performed at one or more nodes by
   one or more traceroute implementations.  Depending on the
   capabilities of a traceroute implementation, not all requested
   parameters can be applied.  Which parameters have actually been
   applied for a specific traceroute measurement is specified in a
   "MeasurementMetadata" element.

   The "RequestMetadata" element is a sequence that contains:

   o  1 "TestName" element;

   o  1 optional "ToolVersion" element;

   o  1 optional "ToolName" element;

   o  1 "CtlTargetAddress" element;

   o  1 optional "CtlBypassRouteTable" element;

   o  1 optional "CtlProbeDataSize" element;

   o  1 optional "CtlTimeOut" element;

   o  1 optional "CtlProbesPerHop" element;

   o  1 optional "CtlPort" element;

   o  1 optional "CtlMaxTtl" element;

   o  1 optional "CtlDSField" element;

   o  1 optional "CtlSourceAddress" element;

   o  1 optional "CtlIfIndex" element;

   o  1 optional "CtlMiscOptions" element;

   o  1 optional "CtlMaxFailures" element;

   o  1 optional "CtlDontFragment" element;

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   o  1 optional "CtlInitialTtl" element;

   o  1 optional "CtlDescr" element;

   o  1 "CtlType" element.

   If the "RequestMetadata" element is omitted from an XML file, it
   means that the traceroute measurement configuration parameters
   requested were all used and the "MeasurementMetadata" element lists
   them in detail.

   The "MeasurementMetadata" element is a sequence that contains:

   o  1 "TestName" element;

   o  1 "OSName" element;

   o  1 "OSVersion" element;

   o  1 "ToolVersion" element;

   o  1 "ToolName" element;

   o  1 "CtlTargetAddressType" element;

   o  1 "CtlTargetAddress" element;

   o  1 "CtlBypassRouteTable" element;

   o  1 "CtlProbeDataSize" element;

   o  1 "CtlTimeOut" element;

   o  1 "CtlProbesPerHop" element;

   o  1 "CtlPort" element;

   o  1 "CtlMaxTtl" element;

   o  1 "CtlDSField" element;

   o  1 "CtlSourceAddressType" element;

   o  1 "CtlSourceAddress" element;

   o  1 "CtlIfIndex" element;

   o  1 optional "CtlMiscOptions" element;

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   o  1 "CtlMaxFailures" element;

   o  1 "CtlDontFragment" element;

   o  1 "CtlInitialTtl" element;

   o  1 optional "CtlDescr" element;

   o  1 "CtlType" element.

   Configuration information elements can describe not just traceroute
   measurements that have already happened ("MeasurementMetadata"
   elements), but also the configuration to be used when requesting a
   measurement to be made ("RequestMetadata" element).  This is quite
   different semantically, even if the individual information elements
   are similar.  Due to this similarity, both "RequestMetadata" and
   "MeasurementMetadata" are represented by the same type in the XML
   schema.  All elements that are missing from the "RequestMetadata" or
   marked as optional in the "RequestMetadata" but mandatory in the
   "MeasurementMetadata" must be specified as empty elements.
   Specifying them as empty elements means use the default value.  The
   "CtlType" element could have been optional in the "RequestMetadata",
   but since default values cannot be specified for complex types in an
   XML schema, the element is mandatory in the "RequestMetadata".

   The "MeasurementResult" element is a sequence that contains:

   o  1 "TestName" element;

   o  1 "ResultsStartDateAndTime" element;

   o  1 "ResultsIpTgtAddrType" element;

   o  1 "ResultsIpTgtAddr" element;

   o  1 "ProbeResults" elements;

   o  1 "ResultsEndDateAndTime" element.

   Additionally, it is important to say that each "ProbeResults" element
   is a sequence that contains:

   o  1..255 "hop" elements.

   Each "hop" element is a sequence that contains:

   o  1..10 "probe" elements;

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   o  1 optional "HopRawOutputData" element.

   Each "probe" element contains:

   o  1 "HopAddrType" element;

   o  1 "HopAddr" element;

   o  1 optional "HopName" element;

   o  0..255 optional "MPLSLabelStackEntry" elements;

   o  1 "ProbedRoundTripTime" element;

   o  1 "ResponseStatus" element;

   o  1 "Time" element.

   Different numbers of appearances of the three basic elements in the
   XML file are meant for different scopes:

   o  a file with only 1 "RequestMetadata" element represents a file
      containing the traceroute measurement configuration parameters of
      a traceroute measurement; it can be used to distribute the
      traceroute measurement configuration parameters over multiple
      nodes asked to run the same traceroute measurement;

   o  a file with 1 "Measurement" element containing 1
      "MeasurementMetadata" and 1 "MeasurementResult" element represents
      a file containing the traceroute measurement information of a
      traceroute measurement;

   o  a file with 1 "Measurement" element containing 1
      "MeasurementMetadata" and n "MeasurementResult" elements
      represents a file containing the traceroute measurement
      information of a set of traceroute measurements run over different
      times with always the same traceroute measurement configuration
      parameters;

   o  a file with 1 "RequestMetadata" and 1 "Measurement" element
      containing 1 "MeasurementMetadata" and 1 "Measurement" element
      represents a file containing the traceroute measurement
      information of a traceroute measurement (containing both the
      requested traceroute measurement configuration parameters and the
      ones actually used);

   o  other combinations are possible to store multiple traceroute
      measurements all in one XML file.

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5.2.2.  Configuration Information Elements

   This section describes the elements specific to the configuration of
   the traceroute measurement (belonging to both the "RequestMetadata"
   and "MeasurementMetadata" elements).

5.2.2.1.  CtlTargetAddressType

   o  name - CtlTargetAddressType

   o  description - Specifies the type of address in the corresponding
      "CtlTargetAddress" element.  This element is not directly
      reflected in the XML schema of Section 7.  The host address type
      can be determined by examining the inetAddress type name and the
      corresponding element value.

   o  dataType - inetAddressType

   o  units - N/A

5.2.2.2.  CtlTargetAddress

   o  name - CtlTargetAddress

   o  description - In the "RequestMetadata" element, it specifies the
      host address requested to be used in the traceroute measurement.
      In the "MeasurementMetadata" element, it specifies the host
      address used in the traceroute measurement.

   o  dataType - inetAddress

   o  units - N/A

5.2.2.3.  CtlBypassRouteTable

   o  name - CtlBypassRouteTable

   o  description - In the "RequestMetadata" element, specifies if the
      optional bypassing of the route table was enabled or not.  In the
      "MeasurementMetadata" element, specifies if the optional bypassing
      of the route table was enabled or not.  If enabled, the normal
      routing tables will be bypassed and the probes will be sent
      directly to a host on an attached network.  If the host is not on
      a directly attached network, an error is returned.  This option
      can be used to perform the traceroute measurement to a local host
      through an interface that has no route defined.  This object can
      be used when the setsockopt SOL_SOCKET SO_DONTROUTE option is
      supported and set (see [IEEE.1003-1G.1997]).

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   o  dataType - boolean

   o  units - N/A

5.2.2.4.  CtlProbeDataSize

   o  name - CtlProbeDataSize

   o  description - Specifies the size of the probes of a traceroute
      measurement in octets (requested if in the "RequestMetadata"
      element, actually used if in the "MeasurementMetadata" element).
      If UDP datagrams are used as probes, then the value contained in
      this object is exact.  If another protocol is used to transmit
      probes (i.e., TCP or ICMP), for which the specified size is not
      appropriate, then the implementation can use whatever size
      (appropriate to the method) is closest to the specified size.  The
      maximum value for this object is computed by subtracting the
      smallest possible IP header size of 20 octets (IPv4 header with no
      options) and the UDP header size of 8 octets from the maximum IP
      packet size.  An IP packet has a maximum size of 65535 octets
      (excluding IPv6 jumbograms).

   o  dataType - unsignedShort

   o  units - octets

5.2.2.5.  CtlTimeOut

   o  name - CtlTimeOut

   o  description - Specifies the timeout value, in seconds, for each
      probe of a traceroute measurement (requested if in the
      "RequestMetadata" element, actually used if in the
      "MeasurementMetadata" element).

   o  dataType - unsignedByte

   o  units - seconds

5.2.2.6.  CtlProbesPerHop

   o  name - CtlProbesPerHop

   o  description - Specifies the number of probes with the same time-
      to-live (TTL) value that are sent for each host (requested if in
      the "RequestMetadata" element, actually used if in the
      "MeasurementMetadata" element).

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   o  dataType - unsignedByte

   o  units - probes

5.2.2.7.  CtlPort

   o  name - CtlPort

   o  description - Specifies the base port used by the traceroute
      measurement (requested if in the "RequestMetadata" element,
      actually used if in the "MeasurementMetadata" element).

   o  dataType - unsignedShort

   o  units - port number

5.2.2.8.  CtlMaxTtl

   o  name - CtlMaxTtl

   o  description - Specifies the maximum TTL value for the traceroute
      measurement (requested if in the "RequestMetadata" element,
      actually used if in the "MeasurementMetadata" element).

   o  dataType - u8nonzero

   o  units - time-to-live value

5.2.2.9.  CtlDSField

   o  name - CtlDSField

   o  description - Specifies the value that was requested to be stored
      in the Differentiated Services (DS) field in the traceroute probe
      (if in the "RequestMetadata" element).  Specifies the value that
      was stored in the Differentiated Services (DS) field in the
      traceroute probe (if in the "MeasurementMetadata" element).  The
      DS field is defined as the Type of Service (TOS) octet in an IPv4
      header or as the Traffic Class octet in an IPv6 header (see
      Section 7 of [RFC2460]).  The value of this object must be a
      decimal integer in the range from 0 to 255.  This option can be
      used to determine what effect an explicit DS field setting has on
      a traceroute measurement and its probes.  Not all values are legal
      or meaningful.  Useful TOS octet values are probably 16 (low
      delay) and 8 (high throughput).  Further references can be found
      in [RFC2474] for the definition of the Differentiated Services
      (DS) field and in [RFC1812] Section 5.3.2 for Type of Service
      (TOS).

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   o  dataType - unsignedByte

   o  units - N/A

5.2.2.10.  CtlSourceAddressType

   o  name - CtlSourceAddressType

   o  description - Specifies the type of address in the corresponding
      "CtlSourceAddress" element.  This element is not directly
      reflected in the XML schema of Section 7.  The host address type
      can be determined by examining the "inetAddress" type name and the
      corresponding element value.  DNS names are not allowed for the
      "CtlSourceAddress".

   o  dataType - inetAddressType

   o  units - N/A

5.2.2.11.  CtlSourceAddress

   o  name - CtlSourceAddress

   o  description - Specifies the IP address (which has to be given as
      an IP number, not a hostname) as the source address in traceroute
      probes (requested if in the "RequestMetadata" element, actually
      used if in the "MeasurementMetadata" element).  On hosts with more
      than one IP address, this option can be used in the
      "RequestMetadata" element to force the source address to be
      something other than the primary IP address of the interface the
      probe is sent on; the value "unknown" means the default address
      will be used.

   o  dataType - inetAddress

   o  units - N/A

5.2.2.12.  CtlIfIndex

   o  name - CtlIfIndex

   o  description - Specifies the interface index as defined in
      [RFC2863] that is requested to be used in the traceroute
      measurement for sending the traceroute probes (if in the
      "RequestMetadata" element).  A value of 0 indicates that no
      specific interface is requested.  Specifies the interface index
      actually used (if in the "MeasurementMetadata" element).

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   o  dataType - unsignedInt

   o  units - N/A

5.2.2.13.  CtlMiscOptions

   o  name - CtlMiscOptions

   o  description - Specifies implementation-dependent options
      (requested if in the "RequestMetadata" element, actually used if
      in the "MeasurementMetadata" element).

   o  dataType - string255

   o  units - N/A

5.2.2.14.  CtlMaxFailures

   o  name - CtlMaxFailures

   o  description - Specifies the maximum number of consecutive timeouts
      allowed before terminating a traceroute measurement (requested if
      in the "RequestMetadata" element, actually used if in the
      "MeasurementMetadata" element).  A value of either 255 (maximum
      hop count/possible TTL value) or 0 indicates that the function of
      terminating a remote traceroute measurement when a specific number
      of consecutive timeouts are detected was disabled.  This element
      is included to give full compatibility with [RFC4560].  No known
      implementation of traceroute currently supports it.

   o  dataType - Unsigned8

   o  units - timeouts

5.2.2.15.  CtlDontFragment

   o  name - CtlDontFragment

   o  description - Specifies if the don't fragment (DF) flag in the IP
      header for a probe was enabled or not (if in the
      "MeasurementMetadata" element).  If in the "RequestMetadata", it
      specifies if the flag was requested to be enabled or not.  Setting
      the DF flag can be used for performing a manual PATH MTU test.

   o  dataType - boolean

   o  units - N/A

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5.2.2.16.  CtlInitialTtl

   o  name - CtlInitialTtl

   o  description - Specifies the initial TTL value for a traceroute
      measurement (requested if in the "RequestMetadata" element,
      actually used if in the "MeasurementMetadata" element).  Such TTL
      setting is intended to bypass the initial (often well-known)
      portion of a path.

   o  dataType - u8nonzero

   o  units - N/A

5.2.2.17.  CtlDescr

   o  name - CtlDescr

   o  description - Provides a description of the traceroute
      measurement.

   o  dataType - string255

   o  units - N/A

5.2.2.18.  CtlType

   o  name - CtlType

   o  description - Specifies the implementation method used for the
      traceroute measurement (requested if in the "RequestMetadata"
      element, actually used if in the "MeasurementMetadata" element).
      It specifies if the traceroute is using TCP, UDP, ICMP, or other
      types of probes.  It is possible to specify other types of probes
      by using an element specified in another schema with a different
      namespace.

   o  dataType - probesType

   o  units - N/A

5.2.3.  Results Information Elements

   This section describes the elements specific to the results of the
   traceroute measurement.

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5.2.3.1.  ResultsStartDateAndTime

   o  name - ResultsStartDateAndTime

   o  description - Specifies the date and start time of the traceroute
      measurement.  This is the time when the first probe was seen at
      the sending interface.

   o  dataType - DateTime

   o  units - N/A

5.2.3.2.  ResultsIpTgtAddrType

   o  name - ResultsIpTgtAddrType

   o  description - Specifies the type of address in the corresponding
      "ResultsIpTgtAddr" element.  This element is not directly
      reflected in the XML schema of Section 7.  The host address type
      can be determined by examining the "inetAddress" type name and the
      corresponding element value.

   o  dataType - inetAddressType

   o  units - N/A

5.2.3.3.  ResultsIpTgtAddr

   o  name - ResultsIpTgtAddr

   o  description - Specifies the IP address associated with a
      "CtlTargetAddress" value when the destination address is specified
      as a DNS name.  The value of this object should be "unknown" if a
      DNS name is not specified or if a specified DNS name fails to
      resolve.

   o  dataType - inetAddress

   o  units - N/A

5.2.3.4.  HopAddrType

   o  name - HopAddrType

   o  description - Specifies the type of address in the corresponding
      "HopAddr" element.  This element is not directly reflected in the
      XML schema of Section 7.  The host address type can be determined

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      by examining the "inetAddress" type name and the corresponding
      element value.  DNS names are not allowed for "HopAddr".

   o  dataType - inetAddressType

   o  units - N/A

5.2.3.5.  HopAddr

   o  name - HopAddr

   o  description - Specifies the address of a hop in the traceroute
      measurement path.  This object is not allowed to be a DNS name.

   o  dataType - inetAddress

   o  units - N/A

5.2.3.6.  HopName

   o  name - HopName

   o  description - Specifies the DNS name of the "HopAddr" if it is
      available.  If it is not available, the element is omitted.

   o  dataType - inetAddress

   o  units - N/A

5.2.3.7.  MPLSLabelStackEntry

   o  name - MPLSLabelStackEntry

   o  description - Specifies entries of the MPLS label stack of a probe
      observed when the probe arrived at the hop that replied to the
      probe.  This object contains one MPLS label stack entry as a
      32-bit value as it is observed on the MPLS label stack.  Contained
      in this single number are the MPLS label, the Exp field, the S
      flag, and the MPLS TTL value as specified in [RFC3032].  If more
      than one MPLS label stack entry is reported, then multiple
      instances of elements of this type are used.  They must be ordered
      in the same order as on the label stack with the top label stack
      entry being reported first.

   o  dataType - unsignedInt

   o  units - N/A

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5.2.3.8.  ProbeRoundTripTime

   o  name - ProbeRoundTripTime

   o  description - If this element contains the element
      "roundTripTime", this specifies the amount of time measured in
      milliseconds from when a probe was sent to when its response was
      received or when it timed out.  The value of this element is
      reported as the truncation of the number reported by the
      traceroute tool (the output "< 1 ms" is therefore encoded as 0
      ms).  If it contains the element "roundTripTimeNotAvailable", it
      means either the probe was lost because of a timeout or it was not
      possible to transmit a probe.

   o  dataType - unsignedShort or string

   o  units - milliseconds or N/A

5.2.3.9.  ResponseStatus

   o  name - ResponseStatus

   o  description - Specifies the result of a traceroute measurement
      made by the host for a particular probe.

   o  dataType - operationResponseStatus

   o  units - N/A

5.2.3.10.  Time

   o  name - Time

   o  description - Specifies the timestamp for the time the response to
      the probe was received at the interface.

   o  dataType - DateTime

   o  units - N/A

5.2.3.11.  ResultsEndDateAndTime

   o  name - ResultsEndDateAndTime

   o  description - Specifies the date and end time of the traceroute
      measurement.  It is either the time when the response to the last
      probe of the traceroute measurement was received or the time when

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      the last probe of the traceroute measurement was sent plus the
      relative timeout (in case of a missing response).

   o  dataType - DateTime

   o  units - N/A

5.2.3.12.  HopRawOutputData

   o  name - HopRawOutputData

   o  description - Specifies the raw output data returned by the
      traceroute measurement for a certain hop in a traceroute
      measurement path.  It is an implementation-dependent, printable
      string, expected to be useful for a human interpreting the
      traceroute results.

   o  dataType - string

   o  units - N/A

5.2.4.  Information Element Correlating Configuration and Results
        Elements

   This section defines an additional element belonging to both previous
   groups (configuration elements and results elements) named
   "TestName".  This element is defined in order to relate configuration
   and results elements by means of a common unique identifier (to be
   chosen in accordance to the specification of [RFC4560]).

5.2.4.1.  TestName

   o  name - TestName

   o  description - Specifies the name of a traceroute measurement.
      This is not necessarily unique within any well-defined scope
      (e.g., a specific host, initiator of the traceroute measurement).

   o  dataType - string255

   o  units - N/A

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5.2.5.  Information Elements to Compare Traceroute Measurement Results
        with Each Other

   This section defines additional elements belonging to both previous
   groups (configuration elements and results elements); these elements
   were defined in order to allow traceroute measurement results
   comparison among different traceroute measurements.

5.2.5.1.  OSName

   o  name - OSName

   o  description - Specifies the name of the operating system on which
      the traceroute measurement was launched.  This element is ignored
      if used in the "RequestMetadata".

   o  dataType - string255

   o  units - N/A

5.2.5.2.  OSVersion

   o  name - OSVersion

   o  description - Specifies the OS version on which the traceroute
      measurement was launched.  This element is ignored if used in the
      "RequestMetadata".

   o  dataType - string255

   o  units - N/A

5.2.5.3.  ToolVersion

   o  name - ToolVersion

   o  description - Specifies the version of the traceroute tool
      (requested to be used if in the "RequestMetadata" element,
      actually used if in the "MeasurementMetadata" element).

   o  dataType - string255

   o  units - N/A

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5.2.5.4.  ToolName

   o  name - ToolName

   o  description - Specifies the name of the traceroute tool (requested
      to be used if in the "RequestMetadata" element, actually used if
      in the "MeasurementMetadata" element).

   o  dataType - string255

   o  units - N/A



(page 23 continued on part 2)

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