P2PSIP Working Group H. Song
Internet-Draft X. Jiang
Intended status: Standards Track R. Even
Expires: September 26, 2013 Huawei
D. Bryan
Ethernot.org
March 25, 2013
P2P Overlay Diagnostics
draft-ietf-p2psip-diagnostics-11
Abstract
This document describes mechanisms for P2P overlay 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.
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This Internet-Draft will expire on September 26, 2013.
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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
5. RELOAD diagnostic extensions . . . . . . . . . . . . . . . . . 10
5.1. Diagnostic Data Structures . . . . . . . . . . . . . . . . 10
5.1.1. DiagnosticsRequest Data Structure . . . . . . . . . . 10
5.1.2. DiagnosticsResponse 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 . . . . . . . . . . . . . . . . . 16
5.3. New Request: PathTrack . . . . . . . . . . . . . . . . . . 16
5.3.1. PathTrack Request . . . . . . . . . . . . . . . . . . 17
5.3.2. PathTrack 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 . . . . . . . . . . . . . . . . . 21
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 21
6.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 22
6.3. Example 3 . . . . . . . . . . . . . . . . . . . . . . . . 22
7. Mandatory Extension . . . . . . . . . . . . . . . . . . . . . 22
8. Authorization through Overlay Configuration . . . . . . . . . 22
9. Security Considerations . . . . . . . . . . . . . . . . . . . 23
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
10.1. Diagnostic Kind ID Types . . . . . . . . . . . . . . . . . 23
10.2. Message Codes . . . . . . . . . . . . . . . . . . . . . . 24
10.3. Error Code . . . . . . . . . . . . . . . . . . . . . . . . 25
10.4. Message Extension . . . . . . . . . . . . . . . . . . . . 25
10.5. Diagnostics Flag . . . . . . . . . . . . . . . . . . . . . 25
10.6. XML Name Space Registration . . . . . . . . . . . . . . . 26
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
12.1. Normative References . . . . . . . . . . . . . . . . . . . 27
12.2. Informative References . . . . . . . . . . . . . . . . . . 27
Appendix A. Problems with Generating Multiple Responses on
Path . . . . . . . . . . . . . . . . . . . . . . . . 28
Appendix B. Changes to the Draft . . . . . . . . . . . . . . . . 28
B.1. Changes since -00 version . . . . . . . . . . . . . . . . 28
B.2. Changes since -01 version . . . . . . . . . . . . . . . . 29
B.3. Changes since -02 version . . . . . . . . . . . . . . . . 29
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B.4. Changes since -03 version . . . . . . . . . . . . . . . . 29
B.5. Changes since -04 version . . . . . . . . . . . . . . . . 29
B.6. Changes since -05 version . . . . . . . . . . . . . . . . 29
B.7. Changes in version -10 . . . . . . . . . . . . . . . . . . 29
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 rely on accurate
and timely detection of failures.
There are a number of situations in which some nodes in a 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 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
node'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 locate failures or monitor performance in
P2PSIP 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 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 node, as well as to
diagnose the path to that node. The second is a new method and
response, 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 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 locate failures
including disabled nodes, congested nodes, 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
PathTrack method) for diagnosing P2PSIP 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 P2PSIP 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 MUST only be provided to authorized nodes.
Some diagnostic information can be provided to all the participants
in the P2PSIP 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 type, where a whole overlay can authorize a certain
type of diagnostic information to a small list of particular nodes
(e.g. administrative nodes). It leaves the scenario where a
particular node authorizes its diagnostic information to a particular
list of nodes out of scope. This could be 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
"permit" unless specified in the diagnostics extension document. As
the RELOAD protocol already requires that each messge carries 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.
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. 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:
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Peer A Peer B Peer C Peer D
| | | |
|(1). PingReq | | |
|------------------->|(2). PingReq | |
| |------------------->|(3). PingReq |
| | |------------------->|
| | | |
| | |<-------------------|
| |<-------------------|(4). PingAns |
|<-------------------|(5). PingAns | |
|(6). PingAns | | |
| | | |
Ping Diagnostic Message Flow
4.2. "Traceroute-like" Behavior: The Path_Track Method
We define a simple PathTrack method for retrieving diagnostic
information iteratively. First, the initiating node asks its
neighbor A which is the next hop peer to the destination ID, and then
retrieves the next hop peer B information, along with optional
diagnostic information of A, to the initiator node. Then the
initiator node asks the next hop peer B (directly or via 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 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 |
|<-------------------|--------------------|--------------------|
| | | |
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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
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 PathTrack as well).
5. RELOAD diagnostic extensions
This document extends RELOAD to carry diagnostic information.
Considering the special usage of diagnostics, this document defines
extensions for a payload to Ping, as well as the new method PathTrack
and its response. Additionally, new Error codes, message bodies for
conveying diagnostics, and some suggested common diagnostic values
are defined. Processing of the PathTrack 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. DiagnosticsRequest 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) } DiagnosticKindId;
struct{
DiagnosticKindId kind;
opaque diagnostic_extension_contents<0..2^32-1>;
}DiagnosticExtension;
struct{
uint64 expiration;
uint64 timestamp_initiated;
uint64 dMFlags;
uint32 length;
DiagnosticExtension diagnostic_extensions[length];
}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]
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 diagnostic 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 request initiator
node 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
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 10.5.
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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:
kind : a numerical code indicating the extension kind of
diagnostic information(see Section 10.1). Note that kind 0xFFFE
is reserved for overlay specific diagnostics and may be used
without IANA registration for local diagnostic information. And
the kind from 0x0000 to 0x003F MUST NOT be indicated in the
diagnostic_extensions in the message request becasue they can be
represented in the dMFlags in a much simpler way.
diagnostic_extension_contents : the opaque data containing the
request for this particular extension. This data is extension
dependent.
5.1.2. 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_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 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.
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.
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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.
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 described in Section 5.1.1.
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 10.1.
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 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
initiator nodes 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 10.5 and the diagnostic kind IDs
are defined in Section 10.1. 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" represent zero load and "0x0F"
represent congested.
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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. Access to this kind of diagnostic information MUST
NOT be allowed unless compliant to the rules defined in Section 8.
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 as
follows: ApplicationProductToken (Platform; OS-or-CPU) *
VendorProductToken (VendorComment). One example is:
MyReloadApp/1.0 (Unix; Linux x86_64) libreload-java/0.7.0
(Stonyfish Inc.). Access to this kind of diagnostic information
MUST NOT be allowed unless compliant to the rules defined in
Section 8.
MACHINE_UPTIME (64 bits): A single value element containing an
unsigned 64-bit integer specifying the time the node 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). Access to this kind of
diagnostic information MUST NOT be allowed unless compliant to the
rules defined in Section 8.
DATASIZE_STORED (64 bits): An unsigned 64-bit integer representing
the number of bytes of data being stored by this node. Access to
this kind of diagnostic information MUST NOT be allowed unless
compliant to the rules defined in Section 8.
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. Access to this kind of
diagnostic information MUST NOT be allowed unless compliant to the
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rules defined in Section 8.
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. Access to
this kind of diagnostic information MUST NOT be allowed unless
compliant to the rules defined in Section 8.
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
five seconds. Access to this kind of diagnostic information MUST
NOT be allowed unless compliant to the rules defined in Section 8.
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 where rcvd_present represents
the bytes received per second since the last calculation and rcvd
represents the last calculation of bytes received per second. A
suitable value for alpha is 0.8. This value is calculated every
five seconds. Access to this kind of diagnostic information MUST
NOT be allowed unless compliant to the rules defined in Section 8.
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 battery or not. If this bit is clear
as '0', then the peer is using a 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 diagnostic information here to collect related
information for calculating self-tuning parameters.
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5.2. 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 and
specified in the RELOAD. 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.
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 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: PathTrack
This document defines a simple PathTrack method 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 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 PathTrack 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 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 can be routed directly or through the overlay based
on the routing mode chosen by the initiator node.
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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 10.2 for the numeric message code for the
new request.
5.3.1. 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.
request : A DiagnosticsRequest, as discussed in Section 5.1.
5.3.2. 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 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
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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 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.
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 PathTrack 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 includes 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. The sender
MAY also include diagnostic extensions for additional information.
If the sender includes any extensions, they MUST calculate the length
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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. 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 PathTrack message, the sender MUST set the
message_code for the RELOAD MessageContents structure for PathTrack.
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.
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 processing 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, either 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
descriptions if they exist.
Each intermediate peer receiving a Ping message with extensions (and
which understands the extension) or receiving a PathTrack request/
response SHOULD check the expiration value (Unix time format) to
determine if the message is 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
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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.
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
PathTrack, 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 is expired. If
the message is 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 the default value for TTL
at the beginning represents 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 request that type of diagnostic information, and if
appropriate, appends the diagnostic information requested in the
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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 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".
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
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 a managed environment, it may
be less of a problem.
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.
6. Examples
Below, we sketch how these metrics can be used.
6.1. 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.
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6.2. 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.
6.3. 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.
7. Mandatory Extension
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 p2psip diagnostics as a mandatory extension to
RELOAD.
<mandatory-extension>
urn:ietf:params:xml:ns:p2p:config-diagnostics
</mandatory-extension>
8. Authorization through Overlay Configuration
The overlay configuration file MUST contain the following XML
elements for authorization a node to access the relative diagnostic
kinds.
diagnostic-kind: This has the attribute "kind" with the hexadecimal
number indicating the diagnostic Kind Type, this attribute has the
same value with Section 10.1, and at least one sub element "access-
node".
access-node: This element contains one hexadecimal number indicating
the node with this NodeID is allowed to access the diagnostic "kind"
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under the same diagnostic-kind emlement.
9. 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. 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.
10. IANA Considerations
10.1. 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 request and
response message, as described in Section 5.1.2. Code points from
0x0000 to 0x003F SHALL be assigned together with flags within "RELOAD
Diagnostics Flag" registry via RFC 5226 [RFC5226] standards action.
Code points in the range 0x0040 to 0xFFFD SHALL be registered via RFC
5226 standards action.
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+----------------------+--------+---------------+
| Diagnostic Kind Type | Code | Specification |
+----------------------+--------+---------------+
| reserved | 0x0000 | RFC-XXXX |
| STATUS_INFO | 0x0001 | RFC-XXXX |
| ROUTING_TABLE_SIZE | 0x0002 | RFC-XXXX |
| PROCESS_POWER | 0x0003 | RFC-XXXX |
| BANDWIDTH | 0x0004 | RFC-XXXX |
| SOFTWARE_VERSION | 0x0005 | RFC-XXXX |
| MACHINE_UPTIME | 0x0006 | RFC-XXXX |
| APP_UPTIME | 0x0007 | RFC-XXXX |
| MEMORY_FOOTPRINT | 0x0008 | RFC-XXXX |
| DATASIZE_STORED | 0x0009 | RFC-XXXX |
| INSTANCES_STORED | 0x000A | RFC-XXXX |
| MESSAGES_SENT_RCVD | 0x000B | RFC-XXXX |
| EWMA_BYTES_SENT | 0x000C | RFC-XXXX |
| EWMA_BYTES_RCVD | 0x000D | RFC-XXXX |
| UNDERLAY_HOP | 0x000E | RFC-XXXX |
| BATTERY_STATUS | 0x000F | RFC-XXXX |
| reserved | 0x003F | RFC-XXXX |
| local use (reserved) | 0xFFFE | RFC-XXXX |
| reserved | 0xFFFF | RFC-XXXX |
+----------------------+--------+---------------+
Table 1: Diagnostic Kind Types
10.2. 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 2: Extensions to RELOAD Message Codes
[To RFC editor: Values starting at 101 were used to prevent
collisions with 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. And all
RFC-AAAA should be replaced with the RFC number of RELOAD when
publication.]
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10.3. 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 3: Extensions to RELOAD Error Codes
10.4. 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
10.5. 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-XXXX|
|STATUS_INFO | 0x 0000 0000 0000 0001 |RFC-XXXX|
|ROUTING_TABLE_SIZE | 0x 0000 0000 0000 0002 |RFC-XXXX|
|PROCESS_POWER | 0x 0000 0000 0000 0004 |RFC-XXXX|
|BANDWIDTH | 0x 0000 0000 0000 0008 |RFC-XXXX|
|SOFTWARE_VERSION | 0x 0000 0000 0000 0010 |RFC-XXXX|
|MACHINE_UPTIME | 0x 0000 0000 0000 0020 |RFC-XXXX|
|APP_UPTIME | 0x 0000 0000 0000 0040 |RFC-XXXX|
|MEMORY_FOOTPRINT | 0x 0000 0000 0000 0080 |RFC-XXXX|
|DATASIZE_STORED | 0x 0000 0000 0000 0100 |RFC-XXXX|
|INSTANCES_STORED | 0x 0000 0000 0000 0200 |RFC-XXXX|
|MESSAGES_SENT_RCVD | 0x 0000 0000 0000 0400 |RFC-XXXX|
|EWMA_BYTES_SENT | 0x 0000 0000 0000 0800 |RFC-XXXX|
|EWMA_BYTES_RCVD | 0x 0000 0000 0000 1000 |RFC-XXXX|
|UNDERLAY_HOP | 0x 0000 0000 0000 2000 |RFC-XXXX|
|BATTERY_STATUS | 0x 0000 0000 0000 4000 |RFC-XXXX|
|Reserved | 0x FFFF FFFF FFFF FFFF |RFC-XXXX|
+-------------------------+------------------------------+--------+
[To RFC editor: Please replace all RFC-XXXX in this document with the
RFC number of this document.]
10.6. 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 p2psip diagnostics as a mandatory extension to
RELOAD.
<mandatory-extension>
urn:ietf:params:xml:ns:p2p:config-diagnostics
</mandatory-extension>
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
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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. References
12.1. 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.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[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-base]
Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)
Base Protocol", draft-ietf-p2psip-base-26 (work in
progress), February 2013.
12.2. Informative References
[UnixTime]
"UnixTime", <Wikipedia, "Unix Time", <http:/wikipedia.org/
wiki/Unix_time>.>.
[I-D.ietf-p2psip-self-tuning]
Maenpaa, J. and G. Camarillo, "A Self-tuning Distributed
Hash Table (DHT) for REsource LOcation And Discovery
(RELOAD)", draft-ietf-p2psip-self-tuning-08 (work in
progress), February 2013.
[I-D.ietf-p2psip-concepts]
Bryan, D., Willis, D., Shim, E., Matthews, P., and S.
Dawkins, "Concepts and Terminology for Peer to Peer SIP",
draft-ietf-p2psip-concepts-04 (work in progress),
October 2011.
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[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.
Appendix A. 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
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 B. Changes to the Draft
To RFC editor: This section is to track the changes. Please remove
this section before publication.
B.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.
B.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.
B.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.
B.4. Changes since -03 version
Modified structure used to share information collected. Both
mechanisms now use a common data structure to convey information.
B.5. Changes since -04 version
Updated the authors' addresses and modified the last sentence in .
(Section 5.3.2)
B.6. Changes since -05 version
Resolve Marc's comments from the mailing list. And define the
details of STATUS_INO.
B.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.
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Authors' Addresses
Haibin Song
Huawei
Email: haibin.song@huawei.com
Jiang Xingfeng
Huawei
Email: jiang.x.f@huawei.com
Roni Even
Huawei
14 David Hamelech
Tel Aviv 64953
Israel
Email: roni.even@mail101.huawei.com
David A. Bryan
Ethernot.org
Williamsburg, Virginia
United States of America
Email: dbryan@ethernot.org
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