P2PSIP Working Group H. Song Internet-Draft X. Jiang Intended status: Standards Track R. Even Expires: August 28, 2016 Huawei D. Bryan ethernot.org Y. Sun ICT February 25, 2016 P2P Overlay Diagnostics draft-ietf-p2psip-diagnostics-20 Abstract This document describes mechanisms for P2P overlay diagnostics. It defines extensions to the RELOAD base protocol 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. 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 August 28, 2016. Copyright Notice Copyright (c) 2016 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 Song, et al. Expires August 28, 2016 [Page 1] Internet-Draft P2P Overlay Diagnostics February 2016 (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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Diagnostic Scenarios . . . . . . . . . . . . . . . . . . . . 4 4. Data Collection Mechanisms . . . . . . . . . . . . . . . . . 5 4.1. Overview of Operations . . . . . . . . . . . . . . . . . 5 4.2. "Ping-like" Behavior: Extending Ping . . . . . . . . . . 7 4.2.1. RELOAD Request Extension: Ping . . . . . . . . . . . 7 4.3. "Traceroute-like" Behavior: The Path_Track Method . . . . 8 4.3.1. New RELOAD Request: PathTrack . . . . . . . . . . . . 9 4.4. Error Code Extensions . . . . . . . . . . . . . . . . . . 11 5. Diagnostic Data Structures . . . . . . . . . . . . . . . . . 11 5.1. DiagnosticsRequest Data Structure . . . . . . . . . . . . 11 5.2. DiagnosticsResponse Data Structure . . . . . . . . . . . 13 5.3. dMFlags and Diagnostic Kind ID Types . . . . . . . . . . 15 6. Message Processing . . . . . . . . . . . . . . . . . . . . . 18 6.1. Message Creation and Transmission . . . . . . . . . . . . 18 6.2. Message Processing: Intermediate Peers . . . . . . . . . 18 6.3. Message Response Creation . . . . . . . . . . . . . . . . 19 6.4. Interpreting Results . . . . . . . . . . . . . . . . . . 20 7. Authorization through Overlay Configuration . . . . . . . . . 21 8. Security Considerations . . . . . . . . . . . . . . . . . . . 21 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 9.1. Diagnostics Flag . . . . . . . . . . . . . . . . . . . . 22 9.2. Diagnostic Kind ID . . . . . . . . . . . . . . . . . . . 22 9.3. Message Codes . . . . . . . . . . . . . . . . . . . . . . 23 9.4. Error Code . . . . . . . . . . . . . . . . . . . . . . . 24 9.5. Message Extension . . . . . . . . . . . . . . . . . . . . 24 9.6. XML Name Space Registration . . . . . . . . . . . . . . . 25 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.1. Normative References . . . . . . . . . . . . . . . . . . 25 11.2. Informative References . . . . . . . . . . . . . . . . . 26 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 27 A.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 27 A.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 27 A.3. Example 3 . . . . . . . . . . . . . . . . . . . . . . . . 27 Appendix B. Problems with Generating Multiple Responses on Path 27 Appendix C. Changes to the Draft . . . . . . . . . . . . . . . . 28 Song, et al. Expires August 28, 2016 [Page 2] Internet-Draft P2P Overlay Diagnostics February 2016 C.1. Changes since -00 version . . . . . . . . . . . . . . . . 28 C.2. Changes since -01 version . . . . . . . . . . . . . . . . 28 C.3. Changes since -02 version . . . . . . . . . . . . . . . . 28 C.4. Changes since -03 version . . . . . . . . . . . . . . . . 28 C.5. Changes since -04 version . . . . . . . . . . . . . . . . 28 C.6. Changes since -05 version . . . . . . . . . . . . . . . . 29 C.7. Changes in version -10 . . . . . . . . . . . . . . . . . 29 C.8. Changes in version -15 . . . . . . . . . . . . . . . . . 29 C.9. Changes in version -20 . . . . . . . . . . . . . . . . . 29 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 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 rely on accurate and timely detection of failures. There are a number of situations in which some nodes in a Peer-to- Peer (P2P) overlay may malfunction or behave badly. For example, these nodes 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 P2P system. Node failures may also be caused by failures of underlying layers. For example, recovery from an incorrect overlay topology may be slow when the speed at which IP routing recovers 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 node's neighbors [Overlay-Failure-Detection], but these algorithms by themselves can only detect the disabled neighbors using the periodic method. This may not be sufficient for the service provider operating the overlay network. Song, et al. Expires August 28, 2016 [Page 3] Internet-Draft P2P Overlay Diagnostics February 2016 A P2P overlay diagnostic framework supporting periodic and on-demand methods for detecting node failures and network failures is desirable. This document describes a general P2P overlay diagnostic extension to the base protocol RELOAD [RFC6940] and is intended as a complement to keep-alive algorithms in the P2P overlay itself. Readers are advised to consult [I-D.ietf-p2psip-concepts] for further background on the problem domain. 2. Terminology This document uses the concepts defined in RELOAD [RFC6940]. 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 setup and configuration of individual P2P nodes requires no network management in the traditional sense. 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]. Unresponsive nodes may only be temporarily disabled, for example due to a local cryptographic processing overload, disk processing overload or link overload. It is therefore useful to repeat the connectivity checks to see 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 used by a particular node to follow up on an individual user complaint or failure. For example, a technical support staff member may use a desktop sharing application (with the permission of the user) to remotely determine the health of, and possible problems with, the malfunctioning node. Part of the remote diagnostics may consist of simple connectivity tests with other nodes in the P2P overlay and retrieval of statistics from Song, et al. Expires August 28, 2016 [Page 4] Internet-Draft P2P Overlay Diagnostics February 2016 nodes in the overlay. The simple connectivity tests are not dependent on the type of P2P overlay. Note that other tests may be required as well, including checking the health and performance of the user's computer or mobile device and checking the bandwidth of the link connecting the user to the Internet. c. P2P system-wide diagnostics used to check the overall health of the P2P overlay network. These include checking the consumption of network bandwidth, checking for the presence of problem links and checking 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], and has not been addressed in earlier documents [Diagnostics_and_NAT_traversal_in_P2PP]. While this is a difficult problem, a great deal of information that can help in diagnosing these problems can be obtained by obtaining basic diagnostic information for peers and the network. This document provides a framework for obtaining this information. 4. Data Collection Mechanisms 4.1. Overview of Operations The diagnostic mechanisms described in this document are primarily intended to detect and locate failures or monitor performance in P2P overlay networks. It provides mechanisms to detect and locate malfunctioning or badly behaving nodes including disabled nodes, congested nodes and misrouting peers. It provides a mechanism to detect direct connectivity or connectivity to a specified node, a mechanism to detect the availability of specified resource records and a mechanism to discover P2P overlay topology and the underlay topology failures. The RELOAD 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 node, as well as to diagnose the path to that node. The second is a new method, PathTrack, 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 document reuses RELOAD [RFC6940]specification and extends them to introduce the new diagnostics methods. The extensions strictly follow how RELOAD specifies message routing, transport, NAT traversal, and other RELOAD protocol features. This document primarily describes how to detect and locate failures including disabled nodes, congested nodes, misrouting behaviors and Song, et al. Expires August 28, 2016 [Page 5] Internet-Draft P2P Overlay Diagnostics February 2016 underlying network faults in P2P overlay networks through a simple and efficient mechanism. This mechanism is modeled after the ping/ traceroute paradigm: ping [RFC0792] is used for connectivity checks, and traceroute is used for hop-by-hop 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 PathTrack method) for diagnosing P2P overlay networks. One way these tools can be used is to detect the connectivity to the specified node or the availability of the specified resource-record through the extended Ping operation. Once the overlay network receives some alarms about overlay service degradation or interruption, a Ping is sent. If the Ping fails, one can then send a PathTrack to determine where the fault lies. The diagnostic information can only be provided to authorized nodes. Some diagnostic information can be provided to all the participants in the P2P overlay, and some other diagnostic information can only be provided to the nodes authorized by the local or overlay policy. The authorization depends on the type of the diagnostic information and the administrative considerations, and is application specific. This document considers the general administrative scenario based on diagnostic Kind, where a whole overlay can authorize a certain kind of diagnostic information to a small list of particular nodes (e.g. administrative nodes). That means, if a node gets the authorization to access a diagnostic Kind, it can access that information from all nodes in the overlay network. It leaves the scenario where a particular node authorizes its diagnostic information to a particular list of nodes out of scope. This could be achieved by extension of this document if there is requirement in the near future. The default policy or access rule for a type of diagnostic information is "deny" unless specified in the diagnostics extension document. As the RELOAD protocol already requires that each message carries the message signature of the sender, the receiver of the diagnostics requests can use the signature to identify the sender. It can then use the overlay configuration file with this signature to determine which types of diagnostic information that node is authorized for. In the remainder of this section we define mechanisms for collecting data, as well as the specific protocol extensions (message extensions, new methods, and error codes) required to collect this information. In Section 5 we discuss the format of the data collected, and in Section 6 we discuss detailed message processing. Song, et al. Expires August 28, 2016 [Page 6] Internet-Draft P2P Overlay Diagnostics February 2016 4.2. "Ping-like" Behavior: Extending Ping To provide "ping-like" behavior, the RELOAD Ping method is 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. 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 | | | | | | | Figure 1: Ping Diagnostic Message Flow 4.2.1. RELOAD Request Extension: Ping To extend the ping request for use in diagnostics, a new extension 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 4. The extension contents consists of a DiagnosticsRequest structure, defined later in this document in Section 5.1. This extension MAY be used for new requests of the Ping method and MUST NOT be included in requests using any other method. Song, et al. Expires August 28, 2016 [Page 7] Internet-Draft P2P Overlay Diagnostics February 2016 This extension is not critical. If a peer does not support the extension, they will simply ignore the diagnostic portion of the message, and will treat the message as 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. 4.3. "Traceroute-like" Behavior: The Path_Track Method We define a simple PathTrack method for retrieving diagnostic information iteratively. The operation of this request is shown below in Figure 2. The initiator node A asks its neighbor B which is the next hop peer to the destination ID, and B returns a message with the next hop peer C information, along with optional diagnostic information for B to the initiator node. Then the initiator node A asks the next hop peer C (direct response routing [RFC7263] or via symmetric routing) to return next hop peer D information and diagnostic information of C. 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 PathTrack message (with diagnostic extensions) is as follows: Peer-A Peer-B Peer-C Peer-D | | | | |(1).PathTrackReq | | | |------------------->| | | |(2).PathTrackAns | | | |<-------------------| | | | |(3).PathTrackReq | | |--------------------|------------------->| | | |(4).PathTrackAns | | |<-------------------|--------------------| | | | |(5).PathTrackReq | |--------------------|--------------------|------------------->| | | |(6).PathTrackAns | |<-------------------|--------------------|--------------------| | | | | Figure 2: PathTrack Diagnostic Message Flow There have been proposals that RouteQuery and a series of Fetch requests can be used to replace the PathTrack mechanism, but in the Song, et al. Expires August 28, 2016 [Page 8] Internet-Draft P2P Overlay Diagnostics February 2016 presence of high rates of churn, such an operation would not, strictly speaking, provide identical results, as the path may change between RouteQuery and Fetch operations. While obviously the path could change between steps of PathTrack as well, with a single message rather than two messages for query and fetch, less inconsistency is likely, and thus the use of a single message is preferred. One important thing is that, this document does not guarantee what it conveys must be the information that caused the previous failures, but with the retrieved information from the previous traversed nodes (with high probability they are, as it cannot guarantee the exact same path), a user or machine can analyze and infer what is the problem. Symmetric routing is achieved by the Via List as defined in [RFC6940] (whatever DHT routing algorithms are used), but response message could go through not exactly the same path as there still can be node failures during that very short period. And there can also be lack of accurate path informaiton of the previously failed message. Given that in a typical diagnostic scenario the peer sending the PathTrack request desires to obtain information about the current path to the destination, in the event that succesive calls to PathTrack return different paths, the results should be discarded and the request resent, ensuring that the second request traverses the appropriate path. 4.3.1. New RELOAD Request: PathTrack This document defines a new RELOAD method, PathTrack, to retrieve the diagnostic information from the intermediate peers along the routing path. At each step of the PathTrack request, the responsible peer responds to the initiator node with requested status information. Status information can include a peer's congestion state, processing power, available bandwidth, the number of entries in its neighbor table, uptime, identity, network address information, and next hop peer information. A PathTrack request specifies which diagnostic information is requested using a DiagnosticsRequest data structure, defined and discussed in detail later in this document in Section 5.1. Base information is requested by setting the appropriate flags in the data structure in the request. If all flags are clear (no bits are set), then the PathTrack request is only used for requesting the next hop information. In this case the iterative mode of PathTrack is degraded to a RouteQuery method which is only used for checking the liveness of the peers along the routing path. The PathTrack request Song, et al. Expires August 28, 2016 [Page 9] Internet-Draft P2P Overlay Diagnostics February 2016 can be routed using direct response routing or other routing methods chosen by the initiator node. A response to a successful PathTrackReq is a PathTrackAns message. The PathTrackAns contains general diagnostic information in the payload, returned using a DiagnosticResponse data structure. This data structure is defined and discussed in detail later in this document in Section 5.2. The information returned is determined based on the information requested in the flags in the corresponding request. 4.3.1.1. PathTrack Request The structure of the PathTrack request is as follows: struct{ Destination destination; DiagnosticsRequest request; }PathTrackReq; The fields of the PathTrackReq are as follows: destination : The destination which the initiator node is interested in. This may be any valid destination object, including a NodeID, opaque ids, or ResourceID. One example should be noted that, for debugging purpose, the initiator will use the destination ID as it was used when failure happened. request : A DiagnosticsRequest, as discussed in Section 5.1. 4.3.1.2. PathTrack Response The structure of the PathTrack 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. 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 receiving a PathTrackAns where the next_hop node ID equals the responding node ID the initiator MUST stop the iterative process. Song, et al. Expires August 28, 2016 [Page 10] Internet-Draft P2P Overlay Diagnostics February 2016 response : A DiagnosticsResponse, as discussed in Section 5.2. 4.4. Error Code Extensions This document extends the Error response method defined in the RELOAD specification to support error cases resulting from diagnostic queries. When an error is encountered in RELOAD, the Message Code 0xFFFF is returned. The ErrorResponse structure includes an error code. We define new error codes to report possible error conditions detected while performing diagnostics: Code Value Error Code Name [TBD1] Underlay Destination Unreachable [TBD2] Underlay Time exceeded [TBD3] Message Expired [TBD4] Upstream Misrouting [TBD5] Loop detected [TBD6] TTL hops exceeded The final error codes will be assigned by IANA as specified in RELOAD protocol [RFC6940]. The error code is returned by the upstreaming node before the failure node. And the upstreaming node uses the normal ping to detect the failure type and return it to the initiator node, which will help the user (initiator node) to understand where the failure happened and what kind of error happened, as the failure may happen at the same location and for the same reason when sending the normal message and the diagnostics message. As defined in RELOAD, additional information may be stored (in an implementation-specific way) in the optional error_info byte string. While the specifics are obviously left to the implementation, as an example, in the case of TBD1, the error_field could be used to provide additional information as to why the underlay destination is unreachable (net unreachable, host unreachable, fragmentation needed, etc.) 5. Diagnostic Data Structures Both the extended Ping method and PathTrack method use the following common diagnostics data structures to collect data. Two common structures are defined: DiagnosticsRequest for requesting data, and DiagnosticsResponse for returning the information. 5.1. DiagnosticsRequest Data Structure The DiagnosticsRequest data structure is used to request diagnostic information and has the following form: Song, et al. Expires August 28, 2016 [Page 11] Internet-Draft P2P Overlay Diagnostics February 2016 enum{ (2^16-1) } DiagnosticKindId; struct{ DiagnosticKindId kind; opaque diagnostic_extension_contents<0..2^32-1>; }DiagnosticExtension; struct{ uint64 expiration; uint64 timestamp_initiated; uint64 dMFlags; uint32 ext_length; DiagnosticExtension diagnostic_extensions_list<0..2^32-1>; }DiagnosticsRequest; The fields in the DiagnosticsRequest are as follows: expiration : The time when the request will expire 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]. This value MUST have a value of between 1 and 600 seconds in the future. This value is used to prevent replay attacks. timestamp_initiated : The time when the 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. dMFlags : A mandatory field which is an unsigned 64-bit integer indicating which base diagnostic information the request initiator node is interested in. The initiator sets different bits to retrieve different kinds of diagnostic information. If dMFlags is set to zero, then no base diagnostic information is conveyed in the PathTrack 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. 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 9.1. ext_length : the length of the extended diagnostic request information in bytes. If the value is greater than or equal to 1, Song, et al. Expires August 28, 2016 [Page 12] Internet-Draft P2P Overlay Diagnostics February 2016 then some extended diagnostic information is being requested, on the assumption this information will be included in the response if the recipient understands the extended request and is willing to provide it. The specific diagnostic information requested is defined in the diagnostic_extensions_list below. A value of zero indicates no extended diagnostic information is being requested. The value of ext_length MUST NOT be negative. Note that it is not the length of the entire DiagnosticsRequest data structure, but of the data making up the diagnostic_extensions_list. diagnostic_extensions_list : consists of one or more DiagnosticExtension structures (see below) documenting additional diagnostic information being requested. Each DiagnosticExtension consists of the following fields: kind : a numerical code indicating the type of extension diagnostic information (see Section 9.2). Note that kinds 0xF000 - 0xFFFE are reserved for overlay specific diagnostics and may be used without IANA registration for local diagnostic information. Kinds from 0x0000 to 0x003F MUST NOT be indicated in the diagnostic_extensions_list in the message request, as they may be represented using the dMFlags in a much simpler (and more space efficient) way. diagnostic_extension_contents : the opaque data containing the request for this particular extension. This data is extension dependent. 5.2. DiagnosticsResponse Data Structure enum { (2^16-1) } DiagnosticKindId; struct{ DiagnosticKindId kind; opaque diagnostic_info_contents<0..2^16-1>; }DiagnosticInfo; struct{ uint64 expiration; uint64 timestamp_initiated; uint64 timestamp_received; uint8 hop_counter; uint32 ext_length; DiagnosticInfo diagnostic_info_list<0..2^32-1>; }DiagnosticsResponse; The fields in the DiagnosticsResponse are as follows: Song, et al. Expires August 28, 2016 [Page 13] Internet-Draft P2P Overlay Diagnostics February 2016 expiration : The time when the response will expire 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. This value MUST have a value of between 1 and 600 seconds in the future. timestamp_initiated: This value is copied from the diagnostics request message. The benefit of containing such a value in the response message is that the initiator node does not have to maintain the state. timestamp_received : The time when the 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 number of hops that the message traversed in the overlay. ext_length : the length of the returned DiagnosticInfo information in bytes. If the value is greater than or equal to 1, then some extended diagnostic information (as specified in the DiagnosticsRequest) was available and is being returned. In that case, this value indicates the length of the returned information. A value of zero indicates no extended diagnostic information is included, either because none was requested or the request could not be accommodated. The value of ext_length MUST NOT be negative. Note that it is not the length of the entire DiagnosticsRequest data structure, but of the data making up the diagnostic_info_list. diagnostic_info_list : consists of one or more DiagnosticInfo structures containing the requested diagnostic_info_contents. 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 described in Section 5.1. For diagnostic extensions, this code will be identical to the value of the DiagnosticKindId set in the "kind" field of the DiagnosticExtension of the request. See Section 9.2. diagnostic_info_contents : Data containing the value for the diagnostic information being reported. Various kinds of Song, et al. Expires August 28, 2016 [Page 14] Internet-Draft P2P Overlay Diagnostics February 2016 diagnostic information can be retrieved, Please refer to Section 5.3 for details of the diagnostic Kind ID for the base diagnostic information that may be reported. 5.3. dMFlags and Diagnostic Kind ID Types The dMFlags field described above is a 64 bit field that allows initiator nodes to identify up to 62 items of base information to request in a request message (the first and last flags being reserved). The dMFlags also reserves all "0"s that means nothing is requested, and all "1"s that means everything is requested. But at the same time, the first and last bits cannot be used for other purposes, and they MUST be set to 0 when other particular diagnostic information kinds are requested. 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 9.1 and the diagnostic Kind IDs are defined in Section 9.2. The information contained for each value is described in this section. Access to each kind of diagnostic information MUST NOT be allowed unless compliant to the rules defined in Section 7. 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 distributed hash table (DHT) network will choose its next hop according to both the DHT routing algorithm and the status information. This is done 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" represent zero load and "0x0F" represent congested. This document does not provide a specific method for congestion, leaving this decision to each overlay implementation. One possible option for an overlay implementation would be to take node's CPU/memory/bandwidth usage percentage in the past 600 seconds and normalize the highest value to the range from 0x00 to 0x0F. And an overlay implementation can also decide to not use all that 16 values from 0x00 to 0x0F. A future draft may define an objective measure or specific algorithm for this. 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 reasons such as routing efficiency. Song, et al. Expires August 28, 2016 [Page 15] Internet-Draft P2P Overlay Diagnostics February 2016 PROCESS_POWER (64 bits): A single value element containing an unsigned 64-bit integer specifying the processing power of the node in unit of MIPS. Fractional values are rounded up. UPSTREAM_BANDWIDTH (64 bits): A single value element containing an unsigned 64-bit integer specifying the upstream network bandwidth (provisioned or maximum, not available) of the node in unit of Kbps. Fractional values are rounded up. For multihomed hosts, this should be the link used to send the response. DOWNSTREAM_BANDWIDTH (64 bits): A single value element containing an unsigned 64-bit integer specifying the downstream network bandwidth (provisioned or maximum, not available) of the node in unit of Kbps. Fractional values are rounded up. For multihomed hosts, this should be the link the request was received from. 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. Given that there are very large number of peers in some networks, and no peer is likely to know all other peer's software, this information may be very useful to help determine if the cause of certain groups of misbehaving peers is related to specific software versions. While the format is peer-defined, a suggested format is as follows: "ApplicationProductToken (Platform; OS-or-CPU) VendorProductToken (VendorComment)". For example: "MyReloadApp/1.0 (Unix; Linux x86_64) libreload-java/0.7.0 (Stonyfish Inc.)". The string is a C-style string, and MUST be terminated by "\0"."\0" MUST NOT be included in the string itself to prevent confusion with the delimiter. MACHINE_UPTIME (64 bits): A single value element containing an unsigned 64-bit integer specifying the time the node's underlying system 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 (64 bits): A single value element containing an unsigned 64-bit integer representing the memory footprint of the peer program in kilobytes (1024 bytes). Fractional values are rounded up. DATASIZE_STORED (64 bits): An unsigned 64-bit integer representing the number of bytes of data being stored by this node. Song, et al. Expires August 28, 2016 [Page 16] Internet-Draft P2P Overlay Diagnostics February 2016 INSTANCES_STORED: An array element containing the number of instances of each kind stored. The array is indexed 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_last where sent_present represents the bytes sent per second since the last calculation and sent_last represents the last calculation of bytes sent per second. A suitable value for alpha is 0.8 (the implementation can decide other suitable value for this). This value is calculated every five seconds (the implementation can also decide other length of the time period). The value for the very first time period should simply be the average of bytes sent in that time period. 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. rcvd = alpha x rcvd_present + (1 - alpha) x rcvd_last where rcvd_present represents the bytes received per second since the last calculation and rcvd_last represents the last calculation of bytes received per second. A suitable value for alpha is 0.8 (the implementation can decide other suitable value for this). This value is calculated every five seconds (the implementation can also decide other length of the time period). The value for the very first time period should simply be the average of bytes received in that time period. UNDERLAY_HOP (8 bits): Indicates the IP layer hops from the intermediate peer which receives the diagnostics message to the next hop peer for this message. (Note: RELOAD does not require the intermediate peers to look into the message body. So here we use PathTrack to gather underlay hops for diagnostics purpose). BATTERY_STATUS (8 bits): The left-most bit is used to indicate whether this peer is using a battery or not. If this bit is clear (set to '0'), then the peer is using a battery for power. The other 7 bits are to be determined by specific applications. Song, et al. Expires August 28, 2016 [Page 17] Internet-Draft P2P Overlay Diagnostics February 2016 6. Message Processing 6.1. Message Creation and Transmission When constructing either a Ping message with diagnostic extensions or a PathTrack message, the sender first creates and populates a DiagnosticsRequest data structure. The timestamp_initiated field is set to the current time, and the expiration field is constructed based on this time. The sender includes the dMFlags field in the structure, setting any number (including all) of the flags to request particular diagnostic information. The sender MAY leave all the bits unset, requesting no particular diagnostic information. The sender MAY also include diagnostic extensions in the DiagnosticsRequest data structure to request additional information. If the sender includes any extensions, it MUST calculate the length of these extensions and set the ext_length field to this value. If no extensions are included, the sender MUST set ext_length to zero. The format of the DiagnosticRequest data structure and its fields MUST follow the restrictions defined in Section 5.1. When constructing a Ping message with diagnostic extensions, the sender MUST create an MessageExtension structure as defined in RELOAD [RFC6940], setting the value of type to 0x0002, and the value of critical to FALSE. The value of extension_contents MUST be a DiagnosticsRequest structure as defined above. The message MAY be directed to a particular NodeId or ResourceID, but MUST NOT be sent to the broadcast NodeID. When constructing a PathTrack message, the sender MUST set the message_code for the RELOAD MessageContents structure to path_track_req TBD7. 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. 6.2. 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 processing this request according to the overlay specified routing mode from RELOAD protocol. In P2P overlay, error responses to a message can be generated by either an intermediate peer or the responsible peer. When a request is received at a peer, the peer may find connectivity failures or Song, et al. Expires August 28, 2016 [Page 18] Internet-Draft P2P Overlay Diagnostics February 2016 malfunctioning peers through the pre-defined rules of the overlay network, e.g. by analyzing via list or underlay error messages. In this case, the intermediate peer returns an error response to the initiator node, reporting any malfunction node information available in the error message payload. All error responses generated MUST contain the appropriate error code. Each intermediate peer receiving a Ping message with extensions (and which understands the extension) or receiving a PathTrack request/ response MUST check the expiration value (Unix time format) to determine if the message is expired. If the message expired, the intermediate peer MUST generate a response with Error Code TBD3 "Message Expired", return the response to the initiator node, and discard the message. The intermediate peer MUST return an error response with the Error Code TBD1 "Underlay Destination Unreachable" when it receives an ICMP message with "Destination Unreachable" information after forwarding the received request to the destination peer. The intermediate peer MUST return an error response with the Error Code TBD2 "Underlay Time Exceeded" when it receives an ICMP message with "Time Exceeded" information after forwarding the received request. The peer MUST return an Error response with Error Code TBD4 "Upstream Misrouting" when it finds its upstream peer disobeys the routing rules defined in the overlay. The immediate upstream peer information MUST also be conveyed to the initiator node. The peer MUST return an Error response with Error Code TBD5 "Loop detected" when it finds a loop through the analysis of via list. The peer MUST return an Error response with Error Code TBD6 "TTL hops exceeded" when it finds that the TTL field value is no more than 0 when forwarding. 6.3. Message Response Creation When a diagnostic request message arrives at a peer, it is responsible for the destination ID specified in the forwarding header, and assuming it understands the extension (in the case of Ping) or the new request type PathTrack, it MUST follow the specifications defined in RELOAD to form the response header, and perform the following operations: Song, et al. Expires August 28, 2016 [Page 19] Internet-Draft P2P Overlay Diagnostics February 2016 When constructing a PathTrack response, the sender MUST set the message_code for the RELOAD MessageContents structure to path_track_ans TBD8. The receiver MUST check the expiration value (Unix time format) in the DiagnosticsRequest to determine if the message is expired. If the message is expired, the peer MUST generate a response with the Error Code TBD3 "Message Expired", return the response to the initiator node, and discard the message. If the message is not expired, the receiver MUST construct a DiagnosticsResponse structure, as follows: The TTL value from the forwarding header is copied to the hop_counter field of the DiagnosticsResponse structure. Note that the default value for TTL at the beginning represents 100-hops unless overlay configuration has overridden the value. The receiver generates an Unix time format timestamp for the current time of day and places it in the timestamp_received field, and constructs a new expiration time and places it in the expiration field of the DiagnosticsResponse. The destination peer MUST check if the initiator node has the authority to request specific types of diagnostic information, and if appropriate, append the diagnostic information requested in the dMFlags and diagnostic_extensions (if any) using the diagnostic_info_list field to the DiagnosticsResponse structure. If any information returned, the receiver MUST calculate the length of the response and set ext_length appropriately. If no diagnostic information is returned, ext_length MUST be set to zero. The format of the DiagnosticResponse data structure and its fields MUST follow the restrictions defined in Section 5.2. In the event of an error, an error response containing the error code followed by the description (if they exist) MUST be created and sent to the sender. If the initiator node asks for diagnostic information that they are not authorized to query, the receiving peer MUST return an Error response with the Error Code 2 "Error_Forbidden". 6.4. 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 measurement, the traditional measurement methods (IP layer ping) MUST be used instead of the overlay layer diagnostics methods. The P2P overlay network using the diagnostics methods specified in this document MUST enforce time synchronization with a central time Song, et al. Expires August 28, 2016 [Page 20] Internet-Draft P2P Overlay Diagnostics February 2016 server. Network Time Protocol [RFC5905] can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions. However, this document does not specify the choice for time resolution and synchronization, leaving it to the implementation. The initiator node receiving the Ping 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. 7. Authorization through Overlay Configuration Different level of access control can be made for different users/ nodes. For example, diagnostic information A can be accessed by node 1 and 2, but diagnostic information B can only be accessed by node 2. The overlay configuration file MUST contain the following XML elements for authorizing a node to access the relative diagnostic Kinds. diagnostic-kind: This has the attribute "kind" with the hexadecimal number indicating the diagnostic Kind ID, this attribute has the same value with Section 9.2, and at least one sub element "access-node". access-node: This element contains one hexadecimal number indicating a NodeID, and the node with this NodeID is allowed to access the diagnostic "kind" under the same diagnostic-kind element. 8. Security Considerations The authorization for diagnostic information must be designed with care to prevent it becoming a method to retrieve information for bot attacks. It should also be noted that attackers can use diagnostics to analyze overlay information to attack certain key peers. For example, diagnostic information might be used to fingerprint a peer where the peer will loose its anonymity characteristics, but anonymity might be very important for some P2P overlay networks, and defenses against such fingerprinting are probably very hard. As such, networks where anonymity is of very high importance may find implementation of diagnostics problematic or even undesirable, despite the many advantages it offers. As this document is a RELOAD extension, it follows RELOAD message header and routing specifications, the common security considerations described in the base document [RFC6940] are also applicable to this document. Overlays may define their own requirements on who can collect/share diagnostic information. Song, et al. Expires August 28, 2016 [Page 21] Internet-Draft P2P Overlay Diagnostics February 2016 9. IANA Considerations 9.1. Diagnostics Flag IANA is asked to create a "RELOAD Diagnostics Flag" Registry under protocol RELOAD. 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 4.3.1. New entries SHALL be defined via [RFC5226] Standards Action. The initial contents of this registry are: +-------------------------+----------------------------+----------+ | diagnostic information |diagnostic flag in dMFlags | RFC | |-------------------------+----------------------------+----------| |Reserved All 0s value | 0x 0000 0000 0000 0000 |RFC-[TBDX]| |Reserved First Bit | 0x 0000 0000 0000 0001 |RFC-[TBDX]| |STATUS_INFO | 0x 0000 0000 0000 0001 |RFC-[TBDX]| |ROUTING_TABLE_SIZE | 0x 0000 0000 0000 0002 |RFC-[TBDX]| |PROCESS_POWER | 0x 0000 0000 0000 0004 |RFC-[TBDX]| |UPSTREAM_BANDWIDTH | 0x 0000 0000 0000 0008 |RFC-[TBDX]| |DOWNSTREAM_ BANDWIDTH | 0x 0000 0000 0000 0010 |RFC-[TBDX]| |SOFTWARE_VERSION | 0x 0000 0000 0000 0020 |RFC-[TBDX]| |MACHINE_UPTIME | 0x 0000 0000 0000 0040 |RFC-[TBDX]| |APP_UPTIME | 0x 0000 0000 0000 0080 |RFC-[TBDX]| |MEMORY_FOOTPRINT | 0x 0000 0000 0000 0100 |RFC-[TBDX]| |DATASIZE_STORED | 0x 0000 0000 0000 0200 |RFC-[TBDX]| |INSTANCES_STORED | 0x 0000 0000 0000 0400 |RFC-[TBDX]| |MESSAGES_SENT_RCVD | 0x 0000 0000 0000 0800 |RFC-[TBDX]| |EWMA_BYTES_SENT | 0x 0000 0000 0000 1000 |RFC-[TBDX]| |EWMA_BYTES_RCVD | 0x 0000 0000 0000 2000 |RFC-[TBDX]| |UNDERLAY_HOP | 0x 0000 0000 0000 4000 |RFC-[TBDX]| |BATTERY_STATUS | 0x 0000 0000 0000 8000 |RFC-[TBDX]| |Reserved Last Bit | 0x 8000 0000 0000 0000 |RFC-[TBDX]| |Reserved All 1s value | 0x FFFF FFFF FFFF FFFF |RFC-[TBDX]| +-------------------------+----------------------------+----------+ [To RFC editor: Please replace all RFC-[TBDX] in this document with the RFC number of this document.] 9.2. Diagnostic Kind ID IANA is asked to create a "RELOAD Diagnostic Kind ID" Registry under protocol RELOAD. Entries in this registry are 16-bit integers denoting diagnostics extension data kinds carried in the diagnostic request and response message, as described in Section 5.2. Code points from 0x0000 to 0x003F are asked to be assigned together with flags within "RELOAD Diagnostics Flag" registry via RFC 5226 Song, et al. Expires August 28, 2016 [Page 22] Internet-Draft P2P Overlay Diagnostics February 2016 [RFC5226] standards action. Code points in the range 0x0040 to 0xEFFF SHALL be registered via RFC 5226 standards action. +---------------------------+---------------+---------------+ | Diagnostic Kind | Code | Specification | +---------------------------+---------------+---------------+ | reserved | 0x0000 | RFC-[TBDX] | | STATUS_INFO | 0x0001 | RFC-[TBDX] | | ROUTING_TABLE_SIZE | 0x0002 | RFC-[TBDX] | | PROCESS_POWER | 0x0003 | RFC-[TBDX] | | UPSTREAM_BANDWIDTH | 0x0004 | RFC-[TBDX] | | DOWNSTREAM_BANDWIDTH | 0x0005 | RFC-[TBDX] | | SOFTWARE_VERSION | 0x0006 | RFC-[TBDX] | | MACHINE_UPTIME | 0x0007 | RFC-[TBDX] | | APP_UPTIME | 0x0008 | RFC-[TBDX] | | MEMORY_FOOTPRINT | 0x0009 | RFC-[TBDX] | | DATASIZE_STORED | 0x000A | RFC-[TBDX] | | INSTANCES_STORED | 0x000B | RFC-[TBDX] | | MESSAGES_SENT_RCVD | 0x000C | RFC-[TBDX] | | EWMA_BYTES_SENT | 0x000D | RFC-[TBDX] | | EWMA_BYTES_RCVD | 0x000E | RFC-[TBDX] | | UNDERLAY_HOP | 0x000F | RFC-[TBDX] | | BATTERY_STATUS | 0x0010 | RFC-[TBDX] | | reserved for future flags | 0x0011-40 | RFC-[TBDX] | | local use (reserved) | 0xF000-0xFFFE | RFC-[TBDX] | | reserved | 0xFFFF | RFC-[TBDX] | +---------------------------+---------------+---------------+ Table 1: Diagnostic Kind 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 [RFC6940]. These additions are: +-------------------+------------+----------+ | Message Code Name | Code Value | RFC | +-------------------+------------+----------+ | path_track_req | [TBD7] | RFC-AAAA | | path_track_ans | [TBD8] | RFC-AAAA | +-------------------+------------+----------+ Table 2: Extensions to RELOAD Message Codes [To RFC editor: Values starting at TBD1 were used to prevent collisions with RELOAD base values and other extensions. Please replace with the next highest available values. The final message Song, et al. Expires August 28, 2016 [Page 23] Internet-Draft P2P Overlay Diagnostics February 2016 codes will be assigned by IANA. And all RFC-AAAA should be replaced with the RFC number of RELOAD when publication.] 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 | [TBD1] | RFC-AAAA | | Error_Underlay_Time_Exceeded | [TBD2] | RFC-AAAA | | Error_Message_Expired | [TBD3] | RFC-AAAA | | Error_Upstream_Misrouting | [TBD4] | RFC-AAAA | | Error_Loop_Detected | [TBD5] | RFC-AAAA | | Error_TTL_Hops_Exceeded | [TBD6] | RFC-AAAA | +----------------------------------------+------------+----------+ Table 3: Extensions to RELOAD Error Codes [To RFC editor: Values starting at TBD1 were used to prevent collisions with RELOAD base values and other extensions. Please replace with the next highest available values. The final message codes will be assigned by IANA. And all RFC-AAAA should be replaced with the RFC number of RELOAD when publication.] 9.5. Message Extension This document introduces the following new RELOAD extension code: +-----------------+------------+----------+ | Extension Name | Code Value | RFC | +-----------------+------------+----------+ | Diagnostic_Ping | 0x0002 | RFC-AAAA | +-----------------+------------+----------+ Table 4: New RELOAD Extension Code [To RFC editor: The value 0x0002 was used to prevent collisions with other extensions. Please replace with the next highest available value. The final codes will be assigned by IANA. And all RFC-AAAA should be replaced with the RFC number of RELOAD when publication.] Song, et al. Expires August 28, 2016 [Page 24] Internet-Draft P2P Overlay Diagnostics February 2016 9.6. XML Name Space Registration This document registers a URI for the config-diagnostics XML namespaces in the IETF XML registry defined in [RFC3688]. All the elements defined in this document belong to this namespace. URI: urn:ietf:params:xml:ns:p2p:config-diagnostics Registrant Contact: The IESG. XML: N/A, the requested URIs are XML namespaces And the overlay configuration file MUST contain the following xml language declaring P2P diagnostics as a mandatory extension to RELOAD. urn:ietf:params:xml:ns:p2p:config-diagnostics 10. Acknowledgments We would like to thank Zheng Hewen for the contribution of the initial version of this document. 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 RELOAD protocol for transferring text about diagnostics to this document. 11. References 11.1. Normative References [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, DOI 10.17487/RFC0792, September 1981, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . Song, et al. Expires August 28, 2016 [Page 25] Internet-Draft P2P Overlay Diagnostics February 2016 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, . [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, . [RFC6940] Jennings, C., Lowekamp, B., Ed., Rescorla, E., Baset, S., and H. Schulzrinne, "REsource LOcation And Discovery (RELOAD) Base Protocol", RFC 6940, DOI 10.17487/RFC6940, January 2014, . [RFC7263] Zong, N., Jiang, X., Even, R., and Y. Zhang, "An Extension to the REsource LOcation And Discovery (RELOAD) Protocol to Support Direct Response Routing", RFC 7263, DOI 10.17487/RFC7263, June 2014, . 11.2. Informative References [UnixTime] "UnixTime", .>. [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-08 (work in progress), February 2016. [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. Song, et al. Expires August 28, 2016 [Page 26] Internet-Draft P2P Overlay Diagnostics February 2016 [Diagnostics_and_NAT_traversal_in_P2PP] Gupta, G., "Diagnostics and NAT Traversal in P2PP - Design and Implementation", Columbia University Report , June 2008. Appendix A. Examples Below, we sketch how these metrics can be used. A.1. Example 1 A peer may set EWMA_BYTES_SENT and EWMA_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. A.2. Example 2 A peer may set the STATUS_INFO Flag in the PathTrackReq to a remote destination peer. The overlay has its own threshold definition for congestion. The peer can obtain knowledge of all the status information of the intermediate peers along the path. Then it can choose other paths to that node for the subsequent requests. A.3. Example 3 A peer may use Ping to evaluate the average overlay hops to other peers by sending PingReq 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. Appendix B. 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. One reason this approach was discarded was 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 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 Song, et al. Expires August 28, 2016 [Page 27] Internet-Draft P2P Overlay Diagnostics February 2016 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. Appendix C. Changes to the Draft To RFC editor: This section is to track the changes. Please remove this section before publication. C.1. Changes since -00 version 1. Changed title from "Diagnose P2PSIP Overlay Network" to "P2PSIP Overlay Diagnostics". 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. C.2. Changes since -01 version Added BATTERY_STATUS as diagnostic information. Removed UnderlayTTL test from the Ping 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. C.3. Changes since -02 version Provided further explanation as to why the base draft Ping in the current form cannot be used to replace Ping, and why some combination of methods cannot replace PathTrack. C.4. Changes since -03 version Modified structure used to share information collected. Both mechanisms now use a common data structure to convey information. C.5. Changes since -04 version Updated the authors' addresses and modified the last sentence in . (Section 4.3.1.2) Song, et al. Expires August 28, 2016 [Page 28] Internet-Draft P2P Overlay Diagnostics February 2016 C.6. Changes since -05 version Resolve Marc's comments from the mailing list. And define the details of STATUS_INO. C.7. Changes in version -10 Resolve the authorization issue and other comments (e.g. define diagnostics as a mandatory extension) from WGLC. And check for the languages. C.8. Changes in version -15 Changed several diagnostic Kind return values to be 64 bit vs. 32 bit to provide headroom. Split bandwidth into upstream and downstream. Renamed length in diagnostic request object to ext_length, added ext_length to response object, and clarified that ext_length is length of diagnostic info/extensions being returned, not the length of the object. Aligned many flags/values with RELOAD by using hex vs decimal values. Significant reorganization and edit for readability. C.9. Changes in version -20 Addressed the IESG comments: (1) this document does not update RFC 6940, but is an extension (2) remove "p2psip" from the document, according to Ben and Benoit's comments (3) update Roni's email address (4) re-check the document to make sure that access control policy is the same (5) change Trust policy from "pre-5378" to "200902" (6) adress the EWMA_BYTES_RCVD and EWMA_BYTES_SENT equation problem rasied by Alisa (7) replace "IANA SHALL" with "IANA is asked to" according to Spencer and Barry's concern (8) replace "SHOULD's with "MUST"s in Section 6.2, change "MAY" to "may" in Section 6.4 according to Ben's comments Song, et al. Expires August 28, 2016 [Page 29] Internet-Draft P2P Overlay Diagnostics February 2016 (9) add a paragraph in Section 4.3 to explain this document does not gurantee the same path fro Path_Track, but only provides information for analysis, according to the list discussion with Alvaro (10) change "directly or via symmetric routing" in Section 4.3 to "direct response routing or via symmetric routing", and give a reference to direct response routing RFC, according to the list discussion with Alvaro (11) change Section 5.3 and 9.1 about the reserved dMFlags bits issue according to Jari and Alexey's comment (12) replace "diagnostic kind type" with "diagnostic Kind" (12) correct other minor editorial issues Authors' Addresses Haibin Song Huawei Email: haibin.song@huawei.com Jiang Xingfeng Huawei Email: jiangxingfeng@huawei.com Roni Even Huawei 14 David Hamelech Tel Aviv 64953 Israel Email: ron.even.tlv@gmail.com David A. Bryan ethernot.org Cedar Park, Texas United States of America Email: dbryan@ethernot.org Song, et al. Expires August 28, 2016 [Page 30] Internet-Draft P2P Overlay Diagnostics February 2016 Yi Sun ICT Email: sunyi@ict.ac.cn Song, et al. Expires August 28, 2016 [Page 31]