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Versions: (draft-zheng-p2psip-diagnose) 00 01 02 03 04 05 06 07 08 09 11 12 13 14 15 16 17 18 19 20 21 22 RFC 7851

P2PSIP Working Group                                             H. Song
Internet-Draft                                                  X. Jiang
Intended status: Standards Track                                 R. Even
Expires: July 1, 2012                                             Huawei
                                                                D. Bryan
                                                                 Polycom
                                                       December 29, 2011


                       P2PSIP Overlay Diagnostics
                    draft-ietf-p2psip-diagnostics-08

Abstract

   This document describes mechanisms for P2PSIP diagnostics.  It
   defines extensions to the RELOAD P2PSIP base protocol RELOAD
   [I-D.ietf-p2psip-base] to collect diagnostic information, and details
   the protocol specifications for these extensions.  Useful diagnostic
   information for connection and node status monitoring is also
   defined.  The document also describes the usage scenarios and
   provides examples of how these methods are used to perform
   diagnostics in a P2PSIP overlay networks.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 1, 2012.

Copyright Notice

   Copyright (c) 2011 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



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   publication of this document.  Please review these documents
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   it for publication as an RFC or to translate it into languages other
   than English.

































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Diagnostic Scenarios . . . . . . . . . . . . . . . . . . . . .  6
   4.  Overview of operations . . . . . . . . . . . . . . . . . . . .  7
     4.1.  "Ping-like" Behavior: Extending Ping . . . . . . . . . . .  8
     4.2.  "Traceroute-like" Behavior: The Path_Track Method  . . . .  9
     4.3.  Problems with Generating Multiple Responses on Path  . . .  9
   5.  RELOAD diagnostic extensions . . . . . . . . . . . . . . . . . 10
     5.1.  Diagnostic Data Structures . . . . . . . . . . . . . . . . 10
       5.1.1.  DiagnosticRequest Data Structure . . . . . . . . . . . 10
       5.1.2.  DiagnosticResponse Data Structure  . . . . . . . . . . 12
       5.1.3.  dMFlags and Diagnostic Kind ID Types . . . . . . . . . 13
       5.1.4.  Extending Diagnostic Information . . . . . . . . . . . 15
     5.2.  Request Extension: Ping  . . . . . . . . . . . . . . . . . 15
     5.3.  New Request: Path_Track  . . . . . . . . . . . . . . . . . 16
       5.3.1.  Path_track Request . . . . . . . . . . . . . . . . . . 16
       5.3.2.  Path_track Response  . . . . . . . . . . . . . . . . . 17
     5.4.  Error Codes  . . . . . . . . . . . . . . . . . . . . . . . 17
     5.5.  Message Processing . . . . . . . . . . . . . . . . . . . . 18
       5.5.1.  Message Creation and Transmission  . . . . . . . . . . 18
       5.5.2.  Message Processing: Intermediate Peers . . . . . . . . 19
       5.5.3.  Message Response Creation  . . . . . . . . . . . . . . 20
       5.5.4.  Interpreting Results . . . . . . . . . . . . . . . . . 20
   6.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     6.1.  Example 1  . . . . . . . . . . . . . . . . . . . . . . . . 21
     6.2.  Example 2  . . . . . . . . . . . . . . . . . . . . . . . . 21
     6.3.  Example 3  . . . . . . . . . . . . . . . . . . . . . . . . 21
   7.  Mandatory Extension  . . . . . . . . . . . . . . . . . . . . . 21
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 22
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 22
     9.1.  Diagnostic Extension Types . . . . . . . . . . . . . . . . 22
     9.2.  Diagnostic Kind ID Types . . . . . . . . . . . . . . . . . 22
     9.3.  Message Codes  . . . . . . . . . . . . . . . . . . . . . . 23
     9.4.  Error Code . . . . . . . . . . . . . . . . . . . . . . . . 24
     9.5.  Message Extension  . . . . . . . . . . . . . . . . . . . . 24
     9.6.  Diagnostics Flag . . . . . . . . . . . . . . . . . . . . . 24
   10. Open Questions . . . . . . . . . . . . . . . . . . . . . . . . 25
   11. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 25
   12. Appendix: Changes to the Draft . . . . . . . . . . . . . . . . 25
     12.1. Changes since -00 version  . . . . . . . . . . . . . . . . 25
     12.2. Changes since -01 version  . . . . . . . . . . . . . . . . 26
     12.3. Changes since -02 version  . . . . . . . . . . . . . . . . 26
     12.4. Changes since -03 version  . . . . . . . . . . . . . . . . 26
     12.5. Changes since -04 version  . . . . . . . . . . . . . . . . 26
     12.6. Changes since -05 version  . . . . . . . . . . . . . . . . 26
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26



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     13.1. Normative References . . . . . . . . . . . . . . . . . . . 26
     13.2. Informative References . . . . . . . . . . . . . . . . . . 27
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29
















































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1.  Introduction

   In the last few years, overlay networks have rapidly evolved and
   emerged as a promising platform for deployment of new applications
   and services in the Internet.  One of the reasons overlay networks
   are seen as an excellent platform for large scale distributed systems
   is their resilience in the presence of failures.  This resilience has
   three aspects: data replication, routing recovery, and static
   resilience.  Routing recovery algorithms are used to repopulate the
   routing table with live nodes when failures are detected.  Static
   resilience measures the extent to which an overlay can route around
   failures even before the recovery algorithm repairs the routing
   table.  Both routing recovery and static resilience relies on
   accurate and timely detection of failures.

   There are a number of situations in which some peers in a P2PSIP
   overlay may malfunction or behave badly.  For example, these peers
   may be disabled, congested, or may be misrouting messages.  The
   impact of these malfunctions on the overlay network may be a
   degradation of quality of service provided collectively by the peers
   in the overlay network or an interruption of the overlay services.
   It is desirable to identify malfunctioning or badly behaving peers
   through diagnostic tools, and exclude or reject them from the P2PSIP
   system.  Node failures may be also caused by underlying failures, for
   example the recovery from an incorrect overlay topology may be slow
   when the IP layer routing failover speed after link failures is very
   slow.  Moreover, if a backbone link fails and the failover is slow,
   the network may be partitioned, leading to partitions of overlay
   topologies and inconsistent routing results between different
   partitioned components.

   Some keep-alive algorithms based on periodic probe and acknowledge
   mechanisms enable accurate and timely detection of failures of one
   peer's neighbors [Overlay-Failure-Detection], but these algorithms by
   themselves can only detect the disabled neighbors using the periodic
   method, it may not be enough for service providers operating the
   overlay network.

   A single, general P2PSIP overlay diagnostic framework supporting
   periodic and on-demand methods for detecting node failures and
   network failures is desirable.  This document describes a general
   P2PSIP overlay diagnostic extension to the P2PSIP base protocol
   RELOAD and is intended as a complement to keep-alive algorithms in
   the P2PSIP overlay itself.







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2.  Terminology

   The concepts used in this document are compatible with "Concepts and
   Terminology for Peer to Peer SIP" [I-D.ietf-p2psip-concepts] and the
   P2PSIP base protocol RELOAD [I-D.ietf-p2psip-base].

   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].


3.  Diagnostic Scenarios

   P2P systems are self-organizing and ideally require no network
   management in the traditional sense to set up and to configure
   individual P2P nodes.  However, users of an overlay, as well as P2P
   service providers may contemplate usage scenarios where some
   monitoring and diagnostics are required.  We present a simple
   connectivity test and some useful diagnostic information that may be
   used in such diagnostics.

   The common usage scenarios for P2P diagnostics can be broadly
   categorized in three classes:

   a.  Automatic diagnostics built into the P2P overlay routing
       protocol.  Nodes perform periodic checks of known neighbors and
       remove those nodes from the routing tables that fail to respond
       to connectivity checks [Handling_Churn_in_a_DHT].  However, the
       unresponsive nodes may only be temporarily disabled, for example
       due to some local cryptographic processing overload, disk
       processing overload or link overload.  It is therefore useful to
       repeat the connectivity checks to see if such nodes have
       recovered and can be again placed in the routing tables.  This
       process is known as 'failed node recovery' and can be optimized
       as described in the paper "Handling Churn in a DHT"
       [Handling_Churn_in_a_DHT].

   b.  Diagnostics for a particular node to follow up an individual user
       complaint or failure.  For example, in this case a technical
       support person may use a desktop sharing application with the
       permission of the user to determine remotely the health and
       possible problems with the malfunctioning node.  Part of the
       remote diagnostics may consist of simple connectivity tests with
       other nodes in the P2PSIP overlay and retrieval statistics of
       nodes from the overlay.  The simple connectivity tests are not
       dependent on the type of P2PSIP overlay.  Note that other tests
       may be required as well, such as checking the health and
       performance of the user's computer or mobile device and also



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       checking the bandwidth of the link connecting the user to the
       Internet.

   c.  P2P system diagnostics to check the overall health of the P2P
       overlay network, the consumption of network bandwidth, for the
       presence of problem links and also to check for abusive or
       malicious nodes.  This is not a trivial problem and has been
       studied in detail for content and streaming P2P overlays
       [Diagnostic_Framework] as well as in earlier P2PSIP documents
       [Diagnostics_and_NAT_traversal_in_P2PP].  While this is a
       difficult problem, a great deal of information can be obtained in
       helping these diagnostics by sending messages to diagnose the
       network.  This document provides a framework for obtaining this
       information.


4.  Overview of operations

   The diagnostic mechanisms described in this document are mainly
   intended to detect and localize failures or monitor performance in
   P2PSIP overlay networks.  It provides mechanisms to detect and
   localize malfunctioning or badly behaving peers including disabled
   peers, congested peers and misrouting peers.  It provides a mechanism
   to detect direct connectivity or connectivity to a specified peer, a
   mechanism to detect the availability of specified resource records
   and a mechanism to discover P2PSIP overlay topology and the underlay
   topology failures.

   The P2PSIP diagnostics extensions define two mechanisms to collect
   data.  The first is an extension to the RELOAD Ping mechanism,
   allowing diagnostic data to be queried from a peer, as well as to
   diagnose the path to that peer.  The second is a new method and
   response, Path_Track, for collecting diagnostic information
   iteratively.  Payloads for these mechanisms allowing diagnostic data
   to be collected and represented are presented, and additional error
   codes are introduced.  Essentially, this draft reuses P2PSIP base
   protocol specification and extends them to introduce the new
   diagnostics methods.  The extensions strictly follow the P2PSIP base
   protocol specification on the messages routing, transport, NAT
   traversal etc.  The diagnostic methods are however P2PSIP protocol
   independent.

   This document primarily describes how to detect and localize failures
   including disabled peers, congested peers, misrouting behaviors and
   underlying network faults in P2PSIP overlay networks through a simple
   and efficient mechanism.  This mechanism is modeled after the ping/
   traceroute paradigm: ping (RFC792 ICMP echo request [RFC0792]) is
   used for connectivity checks, and traceroute is used for hop-by-hop



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   fault localization as well as path tracing.  This document specifies
   a "ping-like" mode (by extending the RELOAD Ping method to gather
   diagnostics) and a "traceroute-like" mode (by defining the new
   Path_Track method) for diagnosing P2PSIP overlay networks.

   One approach these tools can be used is to detect the connectivity to
   the specified peer or the availability of the specified resource-
   record through the extended P2PSIP Ping operation once the overlay
   network receives some alarms about overlay service degradation or
   interruption, if the Ping fails, one can then send a Path_Track to
   determine where the fault lies.

   The diagnostic information must be only provided to authorized peers.
   Some diagnostic information can be authorized to all the participants
   in the P2PSIP overlay, and some other diagnostic information can only
   be provided to the authorization peer list of each diagnostic
   information according to the local or overlay policy.  The
   authorization depends on the kinds of the diagnostic information and
   the administrative considerations, and is application specific.

4.1.  "Ping-like" Behavior: Extending Ping

   To provide "ping-like" behavior, the RELOAD Ping method has been
   extended to collect diagnostic data along the path.  The request
   message is forwarded by the intermediate peers along the path and
   then terminated by the responsible peer, and after optional local
   diagnostics, the responsible peer returns a response message.  If an
   error is found when routing, an Error response is sent to the
   initiator node by the intermediate peer.

   The message flow of a Ping message (with diagnostic extensions) is as
   follows:

   Peer A              Peer B               Peer C             Peer D
     |                    |                    |                    |
     |(1). PingReq        |                    |                    |
     |------------------->|(2). PingReq        |                    |
     |                    |------------------->|(3). PingReq        |
     |                    |                    |------------------->|
     |                    |                    |                    |
     |                    |                    |<-------------------|
     |                    |<-------------------|(4). PingAns        |
     |<-------------------|(5). PingAns        |                    |
     |(6). PingAns        |                    |                    |
     |                    |                    |                    |

                       Ping Diagnostic Message Flow




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4.2.  "Traceroute-like" Behavior: The Path_Track Method

   We define a simple Path_Track method for retrieving diagnostics
   information iteratively.  First, the initiating peer asks its
   neighbor A which is the next hop peer to the destination ID, and then
   retrieve the next hop peer B information, along with optional
   diagnostic information of A, to the initiator peer.  Then the
   initiator peer asks the next hop peer B (directly or symmetric
   routing) to get the further next hop peer C information and
   diagnostic information of B. Unless a failure prevents the message
   from being forwarded, this step can be iteratively repeated until the
   request reaches responsible peer D for the destination ID, and
   retrieves diagnostic information of peer D.

   The message flow of a Path_Track message (with diagnostic extensions)
   is as follows:

   Peer-A              Peer-B               Peer-C             Peer-D
     |                    |                    |                    |
     |(1).Path_TrackReq   |                    |                    |
     |------------------->|                    |                    |
     |(2).Path_TrackAns   |                    |                    |
     |<-------------------|                    |                    |
     |                    |(3).Path_TrackReq   |                    |
     |--------------------|------------------->|                    |
     |                    |(4).Path_TrackAns   |                    |
     |<-------------------|--------------------|                    |
     |                    |                    |(5).Path_TrackReq   |
     |--------------------|--------------------|------------------->|
     |                    |                    |(6).Path_TrackAns   |
     |<-------------------|--------------------|--------------------|
     |                    |                    |                    |

                    Path_Track Diagnostic Message Flow

   There have been proposals made on list that RouteQuery and a series
   of Fetch requests can be used to replace the Path_Track mechanism,
   but in the presence of churn such an operation would not, strictly
   speaking, provide identical results, as the path may change between
   RouteQuery and Fetch operations. (although obviously the path could
   change between steps of Path_Track as well).

4.3.  Problems with Generating Multiple Responses on Path

   An earlier version of this document considered an approach where a
   response was generated by each intermediate peer as the message
   traversed the overlay.  This approach was discarded as a result of
   working group discussion.  One reason this approach was discarded was



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   that it could provide a DoS mechanism, whereby an attacker could send
   an arbitrary message claiming to be from a spoofed "sender" the real
   sender wished to attack.  As a result of sending this one message,
   many messages would be generated and sent back to the spoofed
   "sender" - one from each intermediate peer on the message path.
   While authentication mechanisms could reduce some of the risk of this
   attack, it still resulted in a fundamental break from the request-
   response nature of the RELOAD protocol, as multiple responses are
   generated to a single request.  Although one request with responses
   from all the peers in the route will be more efficient, it was
   determined to be too great a security risk and deviation from the
   RELOAD architecture.


5.  RELOAD diagnostic extensions

   This document extends RELOAD to carry diagnostics information.
   Considering the special usage of diagnostics, this document defines
   extensions for a payload to Ping, as well as the new method
   Path_Track and its response.  Additionally, new Error codes, message
   bodies for conveying diagnostics, and some suggested common
   diagnostic values are defined.  Processing of the Path_Track message
   and the diagnostic bodies is discussed.

   The mechanism defined in this document follows the RELOAD
   specification, the new request and response message use the message
   format specified in P2PSIP base protocol messages.  Please refer to
   the RELOAD [I-D.ietf-p2psip-base] for details of the protocol.

5.1.  Diagnostic Data Structures

   The diagnostics use the following common diagnostics data structures.
   Two common structures are defined, DiagnosticsRequest for requesting
   data, and DiagnosticsResponse for returning information.

5.1.1.  DiagnosticRequest Data Structure

   The DiagnosticsRequest data structure is sent to request diagnostic
   information and has the following form:












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               enum{ (2^16-1) } DiagnosticExtensionRequestType;

               struct{
                   DiagnosticExtensionRequestType type;
                   opaque  diagnostic_extension_contents<0..2^32-1>;
               }DiagnosticExtension;

               struct{
                   uint64 expiration;
                   uint64 timestamp_initiated;
                   uint32 length;
                   DiagnosticExtension diagnostic_extensions[length];
                }DiagnosticsRequest;

   The fields in the DiagnosticsRequest are as follows:

      expiration : The time when the request will be expired represented
      as the number of milliseconds elapsed since midnight Jan 1, 1970
      UTC not counting leap seconds.  This will have the same values for
      seconds as standard UNIX time or POSIX time.  More information can
      be found at UnixTime [UnixTime]

      timestamp_initiated : The time when the P2PSIP diagnostics request
      was initiated represented as the number of milliseconds elapsed
      since midnight Jan 1, 1970 UTC not counting leap seconds.  This
      will have the same values for seconds as standard UNIX time or
      POSIX time.

      length : the length of the extended diagnostic request information
      in bytes.  If the value is greater than or equal to 1, then some
      extended diagnostics information is requested.  The value of
      length must not be negative.

      dMFlags : A mandatory field which is an unsigned 64-bit integer
      indicating which base diagnostic information the initiator is
      interested in.  The initiator sets different bits to retrieve
      different kinds of diagnostic information.  If dMFlags is clear,
      then no base diagnostic information is conveyed in the Path_Track
      response.  If dMFlag is set to all '1's, then all base diagnostic
      information values are requested.  A request may set any number of
      the flags to request the corresponding diagnostic information.

      Note this memo specifies the initial set of flags, the flags can
      be extended by standard action.  The dMflags indicate general
      diagnostic information The mapping between the bits in the dMFlags
      and the diagnostic information kind presented is as described in
      Section 9.6.




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      diagnostic_extensions : consists of one or more
      DiagnosticExtension structures (see below) documenting additional
      diagnostic information being requested.

   Each DiagnosticExtension has the following fields:

      type : the extension type (see Section 9.1) Note that type 0xFFFE
      is reserved for overlay specific diagnostics and may be used
      without IANA registration for local diagnostic information.

      diagnostic_extension_contents : the opaque data containing the
      request for this particular extension.  This data is extension
      dependent.

5.1.2.  DiagnosticResponse Data Structure

               enum { (2^16-1) } DiagnosticKindId;
               struct{
                   DiagnosticKindId kind;
                   opaque diagnostic_info_contents<0..2^16-1>;
               }DiagnosticInfo;

               struct{
                   uint64 expiration;
                   uint64 timestamp_received;
                   uint8 hop_counter;
                   DiagnosticInfo diagnostic_info_list<0..2^32-1>;
               }DiagnosticsResponse;

   The fields in the DiagnosticsResponse are as follows:

      expiration : The time when the response will be expired
      represented as the number of milliseconds elapsed since midnight
      Jan 1, 1970 UTC not counting leap seconds.  This will have the
      same values for seconds as standard UNIX time or POSIX time.

      timestamp_received : The time when P2PSIP Overlay diagnostic
      request was received represented as the number of milliseconds
      elapsed since midnight Jan 1, 1970 UTC not counting leap seconds.
      This will have the same values for seconds as standard UNIX time
      or POSIX time.

      hop_counter : This field only appears in diagnostic responses.  It
      must be exactly copied from the TTL field of the forwarding header
      in the received request.  This information is sent back to the
      request initiator, allowing it to compute the hops that the
      message traversed in the overlay.




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      diagnostic_info_list : consists of one or more DiagnosticInfo
      values containing the requested diagnostic information.

   The fields in the DiagnosticInfo structure are as follows:

      kind : A numeric code indicating the type of information being
      returned.  For base data requested using the dMFlags, this code
      corresponds to the dMFlag set, and is listed in Section 5.1.1
      Paragraph 5.  For diagnostic extensions, this code will be
      identical to the value of the DiagnosticExtensionRequestType set
      in the type field of the DiagnosticExtension of the request, and
      these two values will be assigned together.  See Section 9.2.

      diagnostic_information : Data containing the value for the
      diagnostic information being reported.  Various kinds of
      diagnostic information can be retrieved, Please refer to
      Section 5.1.3 for details of the types and Diagnostic Kind-ID for
      the base diagnostic information that may be reported.

5.1.3.  dMFlags and Diagnostic Kind ID Types

   The dMFlags field described above is a 64 bit field that allows
   requesters to identify up to 62 items of base information to request
   (the first and last flags being reserved) when sending a request.
   When the requested base information is returned in the response, the
   value of the diagnostic kind ID will correspond to the numeric field
   marked in the dMFlags in the request.  The values for the dMFlags are
   defined in Section 9.6 and the diagnostic Kind-IDs are defined in
   Section 9.2.  The information contained for each value is described
   in this section.

      STATUS_INFO (8 bits): A single value element containing an
      unsigned byte representing whether or not the node is in
      congestion status.  An example usage of STATUS_INFO is for
      congestion-aware routing.  In this scenario, each peer has to
      update its congestion status periodically, an intermediate peer in
      the DHT network will choose its next hop according to both the DHT
      routing algorithm and the status information, and then forward
      requests to the chosen next hop, so as to avoid increasing load on
      congested peers.  The rightmost 4 bits are used and other bits
      Must be cleared to "0"s for future use.  There are 16 levels of
      congestion status, with "0x00" respresent zero load and "0x0F"
      representing congested.

      ROUTING_TABLE_SIZE (32 bits): A single value element containing an
      unsigned 32-bit integer representing the number of peers in the
      peer's routing table.  The administrator of the overlay may be
      interested in statistics of this value for the consideration such



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      as routing efficiency.

      PROCESS_POWER (32 bits): A single value element containing an
      unsigned 32-bit integer specifying the processing power of the
      node in unit of MIPS.

      BANDWIDTH (32 bits): A single value element containing an unsigned
      32-bit integer specifying the bandwidth of the node in unit of
      Kbps.

      SOFTWARE_VERSION: A single value element containing a US-ASCII
      string that identifies the manufacture, model, operating system
      information and the version of the software.  The format is like:
      ApplicationProductToken (Platform; OS-or-CPU) * VendorProductToken
      (VendorComment).  One example is: MyReloadApp/1.0 (Unix; Linux
      x86_64) libreload-java/0.7.0 (Stonyfish Inc.).

      MACHINE_UPTIME (64 bits): A single value element containing an
      unsigned 64-bit integer specifying the time the nodes has been up
      in seconds.

      APP_UPTIME (64 bits): A single value element containing an
      unsigned 64-bit integer specifying the time the p2p application
      has been up in seconds.

      MEMORY_FOOTPRINT (32 bits): A single value element containing an
      unsigned 32- bit integer representing the memory footprint of the
      peer program in kibibytes(1024 bytes).

      DATASIZE_STORED (64 bits): An unsigned 64-bit integer representing
      the number of bytes of data being stored by this node.

      INSTANCES_STORED: An array element containing the number of
      instances of each kind stored.  The array is index by Kind-ID.
      Each entry is an unsigned 64-bit integer.

      MESSAGES_SENT_RCVD: An array element containing the number of
      messages sent and received.  The array is indexed by method code.
      Each entry in the array is a pair of unsigned 64-bit integers
      (packed end to end) representing sent and received.

      EWMA_BYTES_SENT (32 bits): A single value element containing an
      unsigned 32-bit integer representing an exponential weighted
      average of bytes sent per second by this peer. sent = alpha x
      sent_present + (1 - alpha) x sent where sent_present represents
      the bytes sent per second since the last calculation and sent
      represents the last calculation of bytes sent per second.  A
      suitable value for alpha is 0.8.  This value is calculated every



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      five seconds.

      EWMA_BYTES_RCVD (32 bits): A single value element containing an
      unsigned 32-bit integer representing an exponential weighted
      average of bytes received per second by this peer.  Same
      calculation as above.

      UNDERLAY_HOP (8 bits): It indicates the IP layer hops from the
      intermediate peer which receives the diagnostics message to its
      next hop peer for this message.  (Note: this is from the
      underlayTTL in the previous version.  However, RELOAD does not
      require the intermediate peers to look into the message body.  So
      here we use Path_Track to gather underlay hops for diagnostics
      purpose.

      BATTERY_STATUS (8 bits): The left-most bit is used to indicate
      whether this peer is using battery or not.  If this bit is clear
      ('0'), then the peer is using battery power.  The other 7 bits are
      to be determined by specific applications.

5.1.4.  Extending Diagnostic Information

   The DiagnosticsExtension structure may be used to extend the
   diagnostic information collected.

   Editor's Note: The self-tuning draft [I-D.ietf-p2psip-self-tuning]
   could extend the diagnostics information here to collect related
   information for calculating self-tuning parameters.

5.2.  Request Extension: Ping

   To extend the ping request for use in diagnostics, a new extension as
   defined in Section 5.3.3 of RELOAD is defined.  The structure for a
   MessageExtension in RELOAD is defined as:

            struct {
              MessageExtensionType  type;
              Boolean               critical;
              opaque                extension_contents<0..2^32-1>;
            } MessageExtension;

   For the Ping request extension, we define a new MessageExtensionType,
   extension 0x0002 named Diagnostic_Ping, as specified in Table 5 and
   specified in the RELOAD draft section 13.14.  The extension contents
   consists of a DiagnosticsRequest structure as defined in
   Section 5.1.1.  This extension MAY be used for new requests of the
   the Ping method and MUST NOT be included in requests using any other
   method.



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   This extension is NOT critical.  If a peer does not extend the
   extension, they will simply ignore the diagnostic portion of the
   message, and will treat the message if it was a normal ping.  Senders
   MUST accept a response that lacks diagnostic information and SHOULD
   NOT resend the message expecting a reply.  Receivers who receive a
   method other than Ping including this extension MUST ignore the
   extension.

5.3.  New Request: Path_Track

   This document defines a simple Path_Track method to retrieve the
   diagnostic information from the intermediate peers along the routing
   path.  At each step of the Path_Track request, the responsible peer
   responds to the initiator node with requested status information such
   as congestion state, its processing power, its available bandwidth,
   the number of entries in its neighbor table, its uptime, its identity
   and network address information, and the next hop peer information.

   A Path_Track request specifies which diagnostic information is
   requested using a DiagnosticsRequest Data structure.  Base
   information is requested by setting the appropriate flags in the
   dMFlags field of the DiagnosticsRequest.  If the flag is clear (no
   bits are set), then the Path_Track request is only used for
   requesting the next hop information.  In this case the iterative mode
   of Path_Track is degraded to a Route_Query method which is only used
   for checking the liveness of the peers along the routing path.  The
   Path_Track request can be routed directly or through the overlay
   based on the routing mode chosen by the initiator node.

   A response to a successful PathTrackReq is a PathTrackAns message.
   There is a general diagnostic information portion of the payload, the
   contents of which are based on the flags in the request.  Please
   refer to Section 5.1.3 for the definitions of the base diagnostic
   information, and Section 9.3 for the numeric message code for the new
   request.

5.3.1.  Path_track Request

   The structure of the Path_track request is as follows:
                           struct{
                               Destination destination;
                               DiagnosticsRequest request;
                           }PathTrackReq;

   The fields of the PathTrackReq are as follows:






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      destination : The destination which the requester is interested
      in.  This may be any valid destination object, including a
      Node-ID, compressed ids, or Resource-ID.

      request : A DiagnosticsRequest, as discussed in Section 5.1.

5.3.2.  Path_track Response

   The structure of the Path_Track Response is as follows:
                              struct{
                                  Destination next_hop;
                                  DiagnosticsResponse response;
                              }PathTrackAns;

   The fields of the PathTrackAns are as follows:

      next_hop : The information of the next hop node from the
      responding intermediate peer to the destination node.  If the
      responding peer is the responsible peer for the destination ID,
      then the next_hop node ID equals the responding node ID, and after
      that the initiator must stop the iterative process.

      response : A DiagnosticsResponse, as discussed in Section 5.1.

5.4.  Error Codes

   This document extends the Error response method defined in the P2PSIP
   base protocol specification to describe the result of diagnostics.
   When an error is encountered in RELOAD, the Message Code 0xFFFF is
   returned.  The ErrorResponse structure includes an error code, and we
   define new error codes to report on possible error conditions
   detected while performing diagnostics:

      Code Value         Error Code Name
      101                Underlay Destination Unreachable
      102                Underlay Time exceeded
      103                Message Expired
      104                Upstream Misrouting
      105                Loop detected
      106                TTL hops exceeded

   The final error codes will be assigned by IANA. as specified in
   section 13.9 of the p2psip base protocol [I-D.ietf-p2psip-base].

   This document introduces several types of error information in the
   error_info field in the case of Code 101.  These are represented as
   an opaque UTF-8 text string.  Here are some examples for the error
   info.



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      error_info:

      net unreachable
      host unreachable
      protocol unreachable
      port unreachable
      fragmentation needed
      source route failed

   The error_info field of the Code 102 to 106 are to be specified by
   the specific overlay.

5.5.  Message Processing

5.5.1.  Message Creation and Transmission

   When constructing either a Ping message with diagnostic extensions or
   a Path_Track message, the sender MUST create a DiagnosticsRequest
   data structure.  The sender MUST set the expiration field of this
   structure in Unix time timestamp format.  The value MUST be at least
   10 seconds in the future, and MUST NOT be more than 600 seconds in
   the future.  The timestamp_initiated field MUST be set to the current
   time in Unix time timestamp format.  The sender MUST include the
   dMFlags field in the structure, and MAY send any number (or all) of
   the flags to request the desired diagnostic information.  The sender
   MAY leave all the bits unset, requesting no diagnostic information,
   but MUST include the field.  The sender MAY also include diagnostic
   extensions for additional information.  If the sender includes any
   extensions, they MUST calculate the length of these extensions and
   set the length field to the correct length.  If no extensions are
   included, the sender MUST set length to zero.

   When constructing a diagnostic ping message, the sender MUST create
   an MessageExtension structure as defined in RELOAD 5.3.3.  The value
   of type MUST be 0x0002.  The value of critical must be FALSE.  The
   value of extension_contents MUST be the DiagnosticsRequest structure
   defined above.  The sender MUST place the MessageExtension structure
   in the extensions field of the MessageContents structure.  The
   message MAY be directed to a particular NodeId or ResourceID, but
   SHOULD NOT be sent to the broadcast NodeID.

   When constructing a Path_Track message, the sender MUST set the
   message_code for the RELOAD MessageContents structure for Path_track.
   The request field of the PathTrackReq must be set to the
   DiagnosticsRequest data structure defined above.  The destination
   field MUST be set to the desired destination, which MAY be either a
   NodeId or ResourceID but SHOULD NOT be the broadcast NodeID.




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5.5.2.  Message Processing: Intermediate Peers

   When a request arrives at a peer, if the peer's responsible ID space
   does not cover the destination ID of the request, then the peer MUST
   continue process this request according to the overlay specified
   routing mode from the base draft.

   In p2psip overlay, the error response can be generated by the
   intermediate peer or responsible peer, to a diagnostic message or
   other messages.  When a request is received at a peer, the peer may
   find some connectivity failures or malfunction peers through the pre-
   defined rules of the overlay network, e.g. by analyzing via list or
   underlay error messages.  The peer SHOULD report the error responses
   to the initiator node.  The malfunction node information should also
   be reported to the initiator node in the error message payload.  All
   error responses contain the Error code followed by the subcode and
   descriptions if existed.

   Each intermediate peer receiving a Ping message with extensions (and
   which understands the extension) or receiving a Path_Track request/
   response SHOULD check the expiration value (Unix time format) to
   determine if the message expired.  If the message expired, the
   intermediate peer SHOULD generate a message with Error Code 103
   "Message Expired" and return it to the initiator node, and discard
   the message.

   The peer should return an Error response with the Error Code 101
   "Underlay Destination Unreachable" when it receives an ICMP message
   with "Destination Unreachable" information after forwarding the
   received request to the destination peer.

   The peer should return an Error response with the Error Code 102
   "Underlay Time Exceeded" when it receives an ICMP message with "Time
   Exceeded" information after forwarding the received request.

   The peer should return an Error response with Error Code 104
   "Upstream Misrouting" when it finds its upstream peer disobeys the
   routing rules defined in the overlay.  The immediate upstream peer
   information should also be conveyed to the initiator node.

   The peer should return an Error response with Error Code 105 "Loop
   detected" when it finds a loop through the analysis of via list.

   The peer should return an Error response with Error Code 106 "TTL
   hops exceeded" when it finds that the TTL field value is no more than
   0 when forwarding.





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5.5.3.  Message Response Creation

   When a diagnostic request message arrives at a peer, it understands
   the extension (in the case of ping) or the new request type
   path_track, and it is responsible for the destination ID specified in
   the forwarding header, it MUST follow the specifications defined in
   5.1.3 of the base draft to form the response header, and perform the
   following operations:

   The receiver MUST check the expiration value (Unix time format) in
   the DiagnosticsRequest to determine if the message expired.  If the
   message expired, the peer MUST generate a message with the Error Code
   103 "Message Expired" and return it to the initiator node, and
   discard the message.

   If the message is not expired, the receiver MUST construct a
   DiagnosticsResponse structure.  The destination peer MUST copy the
   TTL value from the forwarding header to the hop_counter field of the
   DiagnosticsResponse structure.  Note that this value will represent
   100-hops unless overlay configuration has overridden the value.  The
   receiver MUST generate an Unix time format timestamp for the current
   time of day and place it in the timestamp_received field.  The
   receiver MUST construct a new expiration time and place it in the
   expiration field of the DiagnosticsResponse.  This expiration MUST be
   at least 10 seconds in the future and MUST NOT be more than 600
   seconds in the future.

   The destination peer MUST check if the initiator node has the
   authority to get certain kinds of diagnostic information, and if
   appropriate, appends the diagnostic information requested in the
   dMFlags and diagnostic_extensions (if any) in the
   diagnostic_info_list field of the DiagnosticsResponse structure.  If
   there is any information returned, the receiver MUST calculate the
   length of the response and set length appropriately.  If there is no
   diagnostic information returned, length MUST be set to zero.

   In the event of an error, an error response containing the error code
   followed by the subcode and description (if they exist) MUST be
   created and sent to the sender.  If the requester asks for diagnostic
   information that they are not authorized to query, the receiving peer
   MUST return an Error response with the Error Code 1
   "Error_Unauthorized".

5.5.4.  Interpreting Results

   The initiator node, as well as the responding peer, MAY compute the
   overlay One-Way-Delay time through the value in timestamp_received
   and the timestamp_initiated field.  However, for a single hop



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   measurement, the traditional measurement methods MUST be used instead
   of the overlay layer diagnostics methods.

   Editor note: We need more discussion and careful consideration on how
   to use the timestamp here because time synchronization is a barrier
   in open Internet environment, while in the operator's network, it may
   be less of a problem.

   The initiator node receiving the Inspect response MAY check the
   hop_counter field and compute the overlay hops to the destination
   peer for the statistics of connectivity quality from the perspective
   of overlay hops.


6.  Examples

   Below, we sketch how these metrics can be used.

6.1.  Example 1

   A peer may set EWMA_BYTES_SENT and WEMA_BYTES_RCVD flags in the
   PathTrackReq to its direct neighbors.  A peer can use EWMA_BYTES_SENT
   and EWMA_BYTES_RCVD of another peer to infer whether it is acting as
   a media relay.  It may then choose not to forward any requests for
   media relay to this peer.  Similarly, among the various candidates
   for filling up routing table, a peer may prefer a peer with a large
   UPTIME value, small RTT, and small LAST_CONTACT value.

6.2.  Example 2

   A peer may set the StatusInfo Flag in the PathTrackReq to a remote
   destination peer.  The overlay has its own threshold definition for
   congestion.  The peer can get knowledge of all the status information
   of the intermediate peers along the path.  Then it can choose other
   paths to that node for the later requests.

6.3.  Example 3

   A peer may use Inspect to evaluate the average overlay hops to other
   peers by sending InspectReq to a set of random resource or node IDs
   in the overlay.  A peer may adjust its timeout value according to the
   change of average overlay hops.


7.  Mandatory Extension

   This document defines the following XML namespace name for the
   purpose of adding it to a <mandatory-extension> element in the



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   overlay configuration file, to force all nodes of an overlay to
   support diagnostics.
          xmlns:diagnostics="urn:ietf:params:xml:ns:p2p:diagnostics"


8.  Security Considerations

   The authorization for diagnostics information must be designed with
   care to prevent it becoming a resort to retrieve information for bot
   attacks.  It should also be careful that attackers can use
   diagnostics to analyze overlay information to attack certain key
   peers if there are.  As this draft is a RELOAD extension, it follows
   RELOAD message header and routing specifications, the common security
   considerations described in the base draft [I-D.ietf-p2psip-base] are
   also applicable to this draft.  Overlays may define their own
   requirements on who can collect/share diagnostic information.


9.  IANA Considerations

9.1.  Diagnostic Extension Types

   IANA SHALL create a "RELOAD Diagnostic Extension Types" Registry.
   Entries in this registry are 16-bit integers denoting diagnostics
   extension data types in the diagnostic request message, as described
   in Section 5.1.1.  Code points in the range 0x0040 to 0xFFFD SHALL be
   registered via [RFC5226] Standards Action.  The code SHALL be
   assigned together with "RELOAD Diagnostic Kind ID Types" with the
   same value.

   +---------------------------------------+-----------+---------------+
   |       Diagnostic Extension Name       |    Code   | Specification |
   +---------------------------------------+-----------+---------------+
   |  reserved (identifiers used for built |    0 -    |    RFC-BBBB   |
   |               in types)               |   0x003F  |               |
   |          local use (reserved)         |   0xFFFE  |    RFC-BBBB   |
   |                reserved               |   0xFFFF  |    RFC-BBBB   |
   +---------------------------------------+-----------+---------------+

                Table 1: Diagnostic Extension Request Types

9.2.  Diagnostic Kind ID Types

   IANA SHALL create a "RELOAD Diagnostic Kind ID Types" Registry.
   Entries in this registry are 16-bit integers denoting diagnostics
   extension data kind types carried in the diagnostic response message,
   as described in Section 5.1.2.  Code points from 0x0000 to 0x003F
   SHALL be assigned together with flags within "RELOAD Diagnostics



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   Flag" registry via RFC 5226 Standards Action.  Code points in the
   range 0x0040 to 0xFFFD SHALL be registered via RFC 5226 Standards
   Action and be assigned together with same value within "RELOAD
   Diagnostic Extension Types" registry.

             +----------------------+--------+---------------+
             | Diagnostic Kind Type |  Code  | Specification |
             +----------------------+--------+---------------+
             |       reserved       | 0x0000 |    RFC-BBBB   |
             |      STATUS_INFO     | 0x0001 |    RFC-BBBB   |
             |  ROUTING_TABLE_SIZE  | 0x0002 |    RFC-BBBB   |
             |     PROCESS_POWER    | 0x0003 |    RFC-BBBB   |
             |       BANDWIDTH      | 0x0004 |    RFC-BBBB   |
             |   SOFTWARE_VERSION   | 0x0005 |    RFC-BBBB   |
             |    MACHINE_UPTIME    | 0x0006 |    RFC-BBBB   |
             |      APP_UPTIME      | 0x0007 |    RFC-BBBB   |
             |   MEMORY_FOOTPRINT   | 0x0008 |    RFC-BBBB   |
             |    DATASIZE_STORED   | 0x0009 |    RFC-BBBB   |
             |   INSTANCES_STORED   | 0x000A |    RFC-BBBB   |
             |  MESSAGES_SENT_RCVD  | 0x000B |    RFC-BBBB   |
             |    EWMA_BYTES_SENT   | 0x000C |    RFC-BBBB   |
             |    EWMA_BYTES_RCVD   | 0x000D |    RFC-BBBB   |
             |     UNDERLAY_HOP     | 0x000E |    RFC-BBBB   |
             |    BATTERY_STATUS    | 0x000F |    RFC-BBBB   |
             |       reserved       | 0x003F |    RFC-BBBB   |
             | local use (reserved) | 0xFFFE |    RFC-BBBB   |
             |       reserved       | 0xFFFF |    RFC-BBBB   |
             +----------------------+--------+---------------+

                      Table 2: Diagnostic Kind Types

9.3.  Message Codes

   This document introduces two new types of messages and their
   responses, requiring the following additions to the "RELOAD Message
   Code" Registry defined in RELOAD [I-D.ietf-p2psip-base].  These
   additions are:

               +-------------------+------------+----------+
               | Message Code Name | Code Value |    RFC   |
               +-------------------+------------+----------+
               |   path_track_req  |     101    | RFC-AAAA |
               |   path_track_ans  |     102    | RFC-AAAA |
               +-------------------+------------+----------+

                Table 3: Extensions to RELOAD Message Codes

   Note: Values starting at 101 were used to prevent collisions with



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   RELOAD base values.  Once RELOAD moves to RFC, these values may start
   at the next higher value after the RELOAD base values.  The final
   message code will be assigned by IANA.

9.4.  Error Code

   This document introduces the following new error codes, extending the
   "RELOAD Message Code" registry as described below:

    +----------------------------------------+------------+----------+
    |            Message Code Name           | Code Value |    RFC   |
    +----------------------------------------+------------+----------+
    | Error_Underlay_Destination_Unreachable |     101    | RFC-AAAA |
    |      Error_Underlay_Time_Exceeded      |     102    | RFC-AAAA |
    |          Error_Message_Expired         |     103    | RFC-AAAA |
    |        Error_Upstream_Misrouting       |     104    | RFC-AAAA |
    |           Error_Loop_Detected          |     105    | RFC-AAAA |
    |         Error_TTL_Hops_Exceeded        |     106    | RFC-AAAA |
    +----------------------------------------+------------+----------+

                 Table 4: Extensions to RELOAD Error Codes

9.5.  Message Extension

   This document introduces the following new RELOAD extension code:

                +-----------------+------------+----------+
                |  Extension Name | Code Value |    RFC   |
                +-----------------+------------+----------+
                | Diagnostic_Ping |   0x0002   | RFC-AAAA |
                +-----------------+------------+----------+

                    Table 5: New RELOAD Extension Code

9.6.  Diagnostics Flag

   IANA SHALL create a "RELOAD Diagnostics Flag" Registry.  Entries in
   this registry are 1-bit flags contained in a 64-bits long integer
   dMFlags denoting diagnostic information to be retrieved as described
   in Section 5.3.  New entries SHALL be defined via [RFC5226] Standards
   Action.  The initial contents of this registry are:










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    +-------------------------+------------------------------+--------+
    |  diagnostic information |diagnostic flag in dMFlags    | RFC    |
    |-------------------------+------------------------------+--------|
    |Reserved                 | 0x 0000 0000 0000 0000       |RFC-BBBB|
    |STATUS_INFO              | 0x 0000 0000 0000 0001       |RFC-BBBB|
    |ROUTING_TABLE_SIZE       | 0x 0000 0000 0000 0002       |RFC-BBBB|
    |PROCESS_POWER            | 0x 0000 0000 0000 0004       |RFC-BBBB|
    |BANDWIDTH                | 0x 0000 0000 0000 0008       |RFC-BBBB|
    |SOFTWARE_VERSION         | 0x 0000 0000 0000 0010       |RFC-BBBB|
    |MACHINE_UPTIME           | 0x 0000 0000 0000 0020       |RFC-BBBB|
    |APP_UPTIME               | 0x 0000 0000 0000 0040       |RFC-BBBB|
    |MEMORY_FOOTPRINT         | 0x 0000 0000 0000 0080       |RFC-BBBB|
    |DATASIZE_STORED          | 0x 0000 0000 0000 0100       |RFC-BBBB|
    |INSTANCES_STORED         | 0x 0000 0000 0000 0200       |RFC-BBBB|
    |MESSAGES_SENT_RCVD       | 0x 0000 0000 0000 0400       |RFC-BBBB|
    |EWMA_BYTES_SENT          | 0x 0000 0000 0000 0800       |RFC-BBBB|
    |EWMA_BYTES_RCVD          | 0x 0000 0000 0000 1000       |RFC-BBBB|
    |UNDERLAY_HOP             | 0x 0000 0000 0000 2000       |RFC-BBBB|
    |BATTERY_STATUS           | 0x 0000 0000 0000 4000       |RFC-BBBB|
    |Reserved                 | 0x FFFF FFFF FFFF FFFF       |RFC-BBBB|
    +-------------------------+------------------------------+--------+


10.  Open Questions


11.  Acknowledgments

   We would like to thank Zheng Hewen for the contribution of the
   initial version of this draft.  We would also like to thank Bruce
   Lowekamp, Salman Baset, Henning Schulzrinne, Jiang Haifeng and Marc
   Petit-Huguenin for the email discussion and their valued comments,
   and special thanks to Henry Sinnreich for contributing to the usage
   scenarios text.  We would like to thank the authors of the p2psip
   base draft for transferring text about diagnostics to this document.


12.  Appendix: Changes to the Draft

   To RFC editor: This section is to track the changes.  Please remove
   this section before publication.

12.1.  Changes since -00 version

   1.  Changed title from "Diagnose P2PSIP Overlay Network" to "P2PSIP
       Overlay Diagnostics".





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   2.  Changed the table of contents.  Add a section about message
       processing and a section of examples.

   3.  Merge diagnostics text from the p2psip base draft -01.

   4.  Removed ECHO method for security reasons.

12.2.  Changes since -01 version

      Added BATTERY_STATUS as diagnostic information.

      Removed UnderlayTTL test from the Inspect method, instead adding
      an UNDERLAY_HOP diagnostic information for PathTrack method.

      Give some examples for diagnostic information, and give some
      editor's notes for further work.

12.3.  Changes since -02 version

      Provided further explanation as to why the base draft Ping in the
      current form cannot be used to replace Inspect, and why some
      combination of methods cannot replace Path_track.

12.4.  Changes since -03 version

      Modified structure used to share information collected.  Both
      mechanisms now use a common data structure to convey information.

12.5.  Changes since -04 version

   Updated the authors' addresses and modified the last sentence in .
   (Section 5.3.2)

12.6.  Changes since -05 version

   Resolve Marc's comments from the mailing list.  And define the
   details of STATUS_INO.


13.  References

13.1.  Normative References

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, September 1981.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.



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   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [I-D.ietf-p2psip-sip]
              Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
              H. Schulzrinne, "A SIP Usage for RELOAD",
              draft-ietf-p2psip-sip-06 (work in progress), July 2011.

   [I-D.ietf-p2psip-base]
              Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
              H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)
              Base Protocol", draft-ietf-p2psip-base-19 (work in
              progress), October 2011.

   [I-D.zheng-p2psip-diagnose]
              Yongchao, S. and X. Jiang, "Diagnose P2PSIP Overlay
              Network", draft-zheng-p2psip-diagnose-04 (work in
              progress), December 2008.

   [Overlay-Failure-Detection]
              Zhuang, S., "On failure detection algorithms in overlay
              networks",  Proc. IEEE Infocomm, Mar 2005.

   [Handling_Churn_in_a_DHT]
              Rhea, S., "Handling Churn in a DHT", USENIX Annual
              Conference, June 2004.

   [Diagnostic_Framework]
              Jin, X., "A Diagnostic Framework for Peer-to-Peer
              Streaming", 2005.

   [Diagnostics_and_NAT_traversal_in_P2PP]
              Gupta, G., "Diagnostics and NAT Traversal in P2PP - Design
              and Implementation", Columbia University Report ,
              June 2008.

13.2.  Informative References

   [RFC4981]  Risson, J. and T. Moors, "Survey of Research towards
              Robust Peer-to-Peer Networks: Search Methods", RFC 4981,
              September 2007.




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   [I-D.ietf-behave-rfc3489bis]
              Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
              "Session Traversal Utilities for (NAT) (STUN)",
              draft-ietf-behave-rfc3489bis-18 (work in progress),
              July 2008.

   [I-D.matuszewski-p2psip-security-requirements]
              Yongchao, S., Matuszewski, M., and D. York, "P2PSIP
              Security Overview and Risk Analysis",
              draft-matuszewski-p2psip-security-requirements-06 (work in
              progress), September 2009.

   [UnixTime]
              "UnixTime", <Wikipedia, "Unix Time", <http:/wikipedia.org/
              wiki/Unix_time>.>.

   [I-D.song-p2psip-security-eval]
              Yongchao, S., Zhao, B., Jiang, X., and J. Haifeng, "P2PSIP
              Security Analysis and Evaluation",
              draft-song-p2psip-security-eval-00 (work in progress),
              February 2008.

   [I-D.baset-p2psip-p2pp]
              Baset, S., Schulzrinne, H., and M. Matuszewski, "Peer-to-
              Peer Protocol (P2PP)", draft-baset-p2psip-p2pp-01 (work in
              progress), November 2007.

   [I-D.ietf-mmusic-ice]
              Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols",
              draft-ietf-mmusic-ice-19 (work in progress), October 2007.

   [I-D.bryan-p2psip-app-scenarios]
              Bryan, D., Shim, E., Lowekamp, B., and S. Dawkins,
              "Application Scenarios for Peer-to-Peer Session Initiation
              Protocol  (P2PSIP)", draft-bryan-p2psip-app-scenarios-00
              (work in progress), November 2007.

   [I-D.bryan-p2psip-requirements]
              Bryan, D., "P2PSIP Protocol Framework and Requirements",
              draft-bryan-p2psip-requirements-00 (work in progress),
              July 2007.

   [I-D.ietf-p2psip-self-tuning]
              Maenpaa, J., Camarillo, G., and J. Hautakorpi, "A Self-
              tuning Distributed Hash Table (DHT) for REsource LOcation
              And Discovery (RELOAD)", draft-ietf-p2psip-self-tuning-04



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              (work in progress), July 2011.

   [I-D.ietf-p2psip-concepts]
              Bryan, D., Matthews, P., Shim, E., Willis, D., and S.
              Dawkins, "Concepts and Terminology for Peer to Peer SIP",
              draft-ietf-p2psip-concepts-04 (work in progress),
              October 2011.


Authors' Addresses

   Song Haibin
   Huawei
   No. 101, Software Avenue
   Nanjing, Jiangsu Province  210012
   China

   Phone: +86-25-56624792
   Email: haibin.song@huawei.com


   Jiang Xingfeng
   Huawei
   No. 101, Software Avenue
   Nanjing, Jiangsu Province  210012
   China

   Email: jiang.x.f@huawei.com


   Roni Even
   Huawei
   14 David Hamelech
   Tel Aviv 64953
   Israel

   Email: even.roni@huawei.com


   David A. Bryan
   Polycom
   Williamsburg, Virginia
   United States of America

   Email: dbryan@ethernot.org






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