Network Working Group K. Zhang
Request for Comments: 3423 E. Elkin
Category: Informational XACCT Technologies
November 2002
XACCT's Common Reliable Accounting for Network Element (CRANE)
Protocol Specification Version 1.0
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document defines the Common Reliable Accounting for Network
Element (CRANE) protocol that enables efficient and reliable delivery
of any data, mainly accounting data from Network Elements to any
systems, such as mediation systems and Business Support Systems
(BSS)/ Operations Support Systems (OSS). The protocol is developed
to address the critical needs for exporting high volume of accounting
data from NE's with efficient use of network, storage, and processing
resources.
This document specifies the architecture of the protocol and the
message format, which MUST be supported by all CRANE protocol
implementations.
Table of Contents
1 Introduction...................................................2
1.1 Specification of Requirements.............................3
1.2 Terminology...............................................3
2 Protocol Overview..............................................5
2.1 CRANE Architecture........................................6
2.2 CRANE over TCP............................................7
2.3 Alternate servers.........................................7
2.4 Templates.................................................9
2.5 Template Transmission and Negotiation....................10
2.6 Changing Templates.......................................11
2.7 Flow Control.............................................12
2.8 The CRANE Client Query Messages..........................13
Zhang & Elkin Informational [Page 1]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
2.9 CRANE Sessions...........................................13
3 CRANE Message Format..........................................14
4 CRANE Messages................................................16
4.1 Flow Start (START).......................................16
4.2 Flow Start Acknowledge (START ACK).......................16
4.3 Flow Stop (STOP).........................................17
4.4 Flow Stop Acknowledge (STOP ACK).........................17
4.5 Connect (CONNECT)........................................18
4.6 Template Data (TMPL DATA)................................18
4.7 Template Data Acknowledge (TMPL DATA ACK)................23
4.8 Final Template Data (FINAL TMPL DATA)....................25
4.9 Final Template Data Acknowledge (FINAL TMPL DATA ACK)....26
4.10 Get Sessions (GET SESS).................................26
4.11 Get Sessions Response (GET SESS RSP)....................27
4.12 Get Templates (GET TMPL)................................30
4.13 Get Templates Response(GET TMPL RSP)....................30
4.14 Start Negotiation (START NEGOTIATE).....................33
4.15 Start Negotiation Acknowledge (START NEGOTIATE ACK).....34
4.16 Data (DATA).............................................34
4.17 Data Acknowledge (DATA ACK).............................36
4.18 Error (ERROR)...........................................37
4.19 Status Request (STATUS REQ).............................38
4.20 Status Response (STATUS RSP)............................38
5 Protocol Version Negotiation..................................39
6 Security Considerations.......................................42
7 References....................................................43
8 Acknowledgments...............................................43
9 Authors' Addresses............................................44
10 Full Copyright Statement......................................45
1 Introduction
Network Elements are often required to export usage information to
mediation and business support systems (BSS) to facilitate
accounting. Though there are several existing mechanisms for usage
information export, they are becoming inadequate to support the
evolving business requirements from service providers.
For example, some of the export mechanisms are legacies of the Telco
world. Typically usage information is stored in Network Elements as
Log files (e.g., CDR files), and exported to external systems in
batches. These are reliable methods, however, they do not meet the
real-time and high-performance requirements of today's rapidly
evolving data networks.
RADIUS [1] is a widely deployed protocol that may be used for
exporting usage information. However, it can only handle a few
outstanding requests and is not extensible due to its limited command
Zhang & Elkin Informational [Page 2]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
and attribute address space. RADIUS also does not support
unsolicited messages from a server to a client. A detailed analysis
of limitations of RADIUS can be found in [3].
DIAMETER [2] is a new AAA protocol that retains the basic RADIUS
model, and eliminates several drawbacks in RADIUS. The current
DIAMETER protocol and its extensions focus on Internet and wireless
network access, and their support to accounting is closely associated
with authentication/authorization events. DIAMETER is intended to
solve many problems in the AAA area; by doing so, it does not
adequately address some critical issues such as efficiency and
performance in an accounting protocol.
There are also SNMP based mechanisms that generally require a large
amount of processing and bandwidth resources.
Based on the above analysis, a critical need for a reliable, fast,
efficient and flexible accounting protocol exists. The XACCT's CRANE
protocol is designed to address these critical requirements.
This document defines the CRANE protocol that enables efficient and
reliable delivery of any data, mainly accounting data from Network
Elements to any systems, such as mediation systems and BSS/OSS. The
protocol is developed to address the critical needs for exporting
high volume of accounting data from NE's with efficient use of
network, storage, and processing resources.
This document specifies the architecture of the protocol and the
message format, which MUST be supported by all CRANE protocol
implementations.
1.1 Specification of Requirements
In this document, the keywords "MUST", "MUST NOT", "SHOULD", "SHOULD
NOT", and "MAY" are to be interpreted as described in BCP 14 [5].
These keywords are not case sensitive in this document.
1.2 Terminology
CRANE Protocol
CRANE stands for Common Reliable Accounting for Network Element.
The CRANE Protocol maybe referred as CRANE, or the Protocol in
this document. The CRANE Protocol is used at the interface(s)
between a CRANE client and one or multiple CRANE servers for the
purpose of delivering accounting data.
Zhang & Elkin Informational [Page 3]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Client or CRANE Client
A CRANE Client is an implementation on the data producing side of
the CRANE protocol. It is typically integrated with the network
element's software, enabling it to collect and send out accounting
data to a mediation/billing system using the protocol defined
herein.
Server or CRANE Server
A CRANE Server is an implementation on the data receiving side of
the CRANE protocol. It is typically part of a Business Support
System (BSS) (e.g., Billing, Market Analysis, Fraud detection,
etc.), or a mediation system. There could be more than one CRANE
server connected to one CRANE client to improve robustness of the
usage information export system.
CRANE Session
A CRANE Session is a logical connection between a CRANE client and
one or multiple CRANE servers for the purpose of delivering
accounting data. Multiple sessions MAY be maintained concurrently
in a CRANE client or a CRANE server; they are distinguished by
Session IDs.
Server Priority
A CRANE server is assigned with a Priority value. Accounting data
is always delivered to the perceived operating CRANE server (from
the CRANE client point of view) with the highest Priority value
(the primary server) within a CRANE Session.
Message
A Message is encoded according to rules specified by the CRANE
protocol and transmitted across the interface between a CRANE
client and a CRANE server. It contains a common CRANE header and
optionally control or user data payload.
Data Record
A Data Record is a collection of information gathered by the
Network Element for various purposes, e.g., accounting. The
structure of a Data Record is defined by a Template.
Zhang & Elkin Informational [Page 4]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Template
A Template defines the structure of any types of Data Record, and
specifies the data type, meaning, and location of the fields in
the record.
Data Sequence Number (DSN)
An accounting Data Record level sequence number, which is attached
to all data messages to facilitate reliable and in-sequence
delivery.
2 Protocol Overview
The CRANE protocol is designed to deliver accounting data reliably,
efficiently, and quickly. Due to the nature of accounting data,
large records often need to be transmitted; thus supporting
fragmentation of large records is required. Furthermore, the value
associated with accounting data is high; to prevent data loss, quick
detection of unresponsive CRANE servers is also required for added
robustness.
The CRANE protocol can be viewed as an application that uses the data
transport service provided by lower layer protocols. It relies on a
transport layer protocol to deliver reliable, in-sequence data
packets.
UDP is a simple connectionless transport layer protocol that has
advantages of being fast and agile, but it provides no reliability
and lacks flow control mechanisms. Hence, The CRANE protocol must
not use UDP as the transport layer protocol to avoid the risk of
adversely impacting the networks it is being run over.
TCP and SCTP [4] are two transport layer protocols that fulfill the
reliability requirement of CRANE. Either one of them MAY be used to
transport CRANE messages. TCP meets some of the requirements, but
not all (e.g., quick detection of server failure, the fact that TCP
is stream oriented and not record oriented). Therefore, SCTP [4] is
the preferred way to transmit CRANE messages.
Zhang & Elkin Informational [Page 5]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
2.1 CRANE Architecture
The CRANE protocol is an application running over a reliable
transport layer protocol. The transport layer protocol is
responsible for delivering CRANE messages between CRANE clients and
CRANE servers. It MUST support the following capabilities:
1. Reliable, in-sequence message delivery.
2. Connection oriented.
3. Delivery of messages with a length of up to 2^32 octets (i.e., the
transport layer has to support fragmentation of messages when
running over IP).
The transport layer MAY support:
1. Authentication.
2. Bundling of multiple messages into a single datagram.
Possible transport layer protocols MAY be TCP or SCTP [4]. TCP
supports the minimal requirements for CRANE, but lacks some desirable
capabilities that are available in SCTP, these include:
1. Session level authentication.
2. Message based data delivery (as opposed to stream based).
3. Fast connection failure detection.
Reliable delivery of accounting data is achieved through both the
transport layer level and the CRANE protocol level. The transport
layer acknowledgments are used to ensure quick detection of lost data
packets and unresponsive servers, while the CRANE protocol
acknowledges CRANE messages after they have been processed and the
accounting information has been placed in persistent storage.
Being a reliable protocol for delivering accounting data, traffic
flowing from a CRANE client to a CRANE server is mostly accounting
data. There are also bi-directional control message exchanges,
though they only comprise of small portion of the traffic.
Zhang & Elkin Informational [Page 6]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
The following diagram illustrates the CRANE protocol architecture:
+----------------+ +----------------+
| CRANE | | CRANE |+
| User | | User ||+
+----------------+ +----------------+||
| CRANE | ==========> | CRANE |+|
| Client | <---------- | Server ||+
+----------------+ +----------------+||
| Transport | | Transport |+|
| Layer | <---------> | Layer ||+
+----------------+ +----------------+||
| Lower | | Lower |+|
| Layers | <---------> | Layers ||+
+----------------+ +----------------+||
+----------------+|
+----------------+
2.2 CRANE over TCP
TCP can be used as a transport layer for the CRANE protocol. CRANE
running over TCP MUST conform to the following rules:
1. The CRANE client MUST accept TCP connections over a specific TCP
port.
2. The CRANE server MUST connect to the CRANE client, and SHOULD be
responsible for reestablishing a connection in case of a failure.
3. CRANE messages are written as a stream of bytes into a TCP
connection, the size of a CRANE message is specified by the
Message Length field in the CRANE message header.
2.3 Alternate servers
For purposes of improved reliability and robustness, redundant CRANE
server configuration MAY be employed. The CRANE protocol supports
delivering accounting data to alternate CRANE servers, which may be
part of a mediation system or a BSS.
A CRANE session may comprise of one or more CRANE servers. The CRANE
client is responsible for configuring network addresses of all CRANE
servers belonging to the session. A Server Priority is assigned to
each CRANE server. The Server Priority reflects the CRANE client's
preference regarding which CRANE server should receive accounting
data. The assignment of the Server Priority should consider factors
such as geographical distance, communication cost, and CRANE server
loading, etc. It is also possible for several CRANE servers to have
the same priority. In this case, the CRANE client could randomly
choose one of them as the primary server to deliver accounting data.
Zhang & Elkin Informational [Page 7]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Additional features such as load balancing may be implemented in a
multi-server environment. The process of configuring CRANE client is
carried out using the NE's configuration system and is outside the
scope of this document.
A CRANE client MUST deliver accounting data to its perceived
operating CRANE server with the highest priority; if this CRANE
server is deemed unreachable, the CRANE client MUST deliver the
accounting data to the next highest priority CRANE server that is
perceived to be operating. If no perceived operating CRANE servers
are available, accounting data MUST be queued in the CRANE client
until any CRANE server is available or the client's queue space runs
out. An alarm should be generated to inform the CRANE user of the
queue overflow condition.
Accounting data delivery SHOULD revert to the higher priority server
when it is perceived to be operating again.
The CRANE protocol does not specify how a CRANE client should
redirect accounting data to other CRANE servers, which is considered
an implementation issue. But all the supporting mechanisms are
provided by the protocol to work in a multiple-server environment
(e.g., the template negotiation process, and configuration
procedures, etc.). The transport layer (together with some other
means) is responsible for monitoring server's responsiveness and
notifying CRANE protocol for any failures. The client may choose to
transition to an alternate server.
Implementation Note:
The transition to an alternate CRANE server is an implementation
issue and should occur under the following conditions:
A) Transport layer notifies the CRANE client that the
corresponding port of the CRANE server is unresponsive.
B) Total size of unacknowledged accounting records has exceeded a
threshold (configurable) for certain duration (configurable).
C) A STOP message is received from the active server.
D) A lower priority server is the active one and a higher priority
server has recovered.
Zhang & Elkin Informational [Page 8]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
2.4 Templates
The CRANE protocol enables efficient delivery of accounting data.
This is achieved by negotiating a set of Data Templates for a CRANE
session before actual accounting data is delivered. A data template
defines the structure of a DATA message payload by describing the
data type, meaning, and location of the fields in the payload. By
agreeing on session templates, CRANE servers understand how to
process DATA messages received from a CRANE client. As a result, a
CRANE client only needs to deliver actual accounting data without
attaching any descriptors of the data; this reduces the amount of
bytes sent over communication links.
A template is an ordered list of keys. A key is the specification of
a field in the template. It specifies an accounting item that a
network element MAY collect and export. The specification MUST
consist of the description and the data type of the accounting item.
(e.g., 'Number of Sent Bytes' can be a key that is an unsigned
integer of 32 bit long). A CRANE client typically defines keys.
The CRANE protocol supports usage of several templates concurrently
(for different accounting records). Keys contained in a template
could be enabled or disabled. An enabled key implies that the
outgoing data record will contain the data item specified by the key.
A disabled key implies that the outgoing record will omit the
specified data item. The enabling/disabling mechanism further
reduces bandwidth requirement; it could also reduce processing in
network elements, as only needed data items are produced.
In a CRANE session, all the CRANE servers and the CRANE client MUST
use the same set of templates and associated enable/disable status.
The templates' configuration and connectivity to an end application
MUST be the same in all servers. The CRANE client MUST publish the
relevant templates to all CRANE servers in a session through user
configuration, before it starts to send data according to the
templates.
The complete set of templates residing in a CRANE client MUST bear a
configuration ID that identifies the template set. Each data record
is delivered with the Template ID and the Configuration ID, so that
the correct template can be referenced. A server, when receiving a
record with an older Configuration ID, MAY handle the record
gracefully by keeping some template history. The transport layer
should ensure that a server would not get messages with future
configuration IDs.
Zhang & Elkin Informational [Page 9]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
2.5 Template Transmission and Negotiation
As stated before, all CRANE servers MUST use the same set of
templates in a CRANE session. In case that servers do not share the
same set of templates (the templates are considered different if
different keys are enabled or disabled), a negotiation process
between the client and the server would ultimately determine one set
of templates that is accepted and used by all the CRANE servers in a
session.
After a CRANE session is established and the server sent a START
message indicating that it is ready to take part in the session, the
client MUST deliver the set of templates that it intends to use by
sending a TMPL DATA message to the server. The CRANE server MUST
acknowledge the reception of the set of templates.
Templates are negotiable between a CRANE client and CRANE servers. A
CRANE server may propose changes to the templates received from a
CRANE client (e.g., enabling some keys and disabling others), or it
can acknowledge the templates as is. In the case that a template or
a key is not recognized by the server (e.g., they might be added to
the client after the server configuration has completed), the server
MAY choose to disable each unknown key or unknown templates in order
to avoid unnecessary traffic. A template is disabled when all the
keys are disabled. If changes were received from the CRANE servers,
the client will send the changed template set to all connected
servers (using FINAL_TMPL_DATA message). It is the client's
responsibility to decide what would be the final set of templates
used by a session. At this time, each CRANE server MUST accept and
acknowledge the templates without changing anything (to avoid
deadlock and loop conditions). Each CRANE server is given a single
chance to propose any changes during the negotiation process.
The template negotiation process is outlined as follows:
A) CRANE client sends a TMPL DATA message with a set of templates.
B) CRANE server either responds with the TMPL DATA ACK message with
changes in the template set (process continues in step C) or responds
with FINAL TMPL DATA ACK message if no changes are needed (process
continues in step E).
C) CRANE client receives proposed changes, incorporates them if
possible and then sends a FINAL TMPL DATA message containing the new
set of templates to all servers (in order to deploy the change).
D) CRANE server receives the FINAL TMPL DATA message containing the
new set of templates and MUST send a FINAL TMPL DATA ACK message to
Zhang & Elkin Informational [Page 10]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
acknowledge the reception of the templates. No changes are allowed
at this stage and the templates, which the client sent, are going to
be used.
E) CRANE client receives a FINAL TMPL DATA ACK message from the
server and can assume that the server knows which templates to use.
All these stages take place only when there are multiple CRANE
servers with differences in the template set (e.g., not all key
states are identical). If all CRANE servers within a session share
the same configuration exactly, all servers will respond with FINAL
TMPL DATA ACK and the ping-pong between the client and the servers
will end immediately. This is the common case, but in case some
other CRANE servers have a different configuration, the protocol
offers the way to maintain consistency among CRANE servers.
Implementation Note:
TMPL DATA messages SHOULD be sent only after all DATA messages
with the previous configuration have been acknowledged. This
ensures the server to transition properly to the new
configuration.
2.6 Changing Templates
Though TMPL DATA messages allow for deploying and publicizing
template, a need to configure the template set still exists. Each of
the CRANE servers in a CRANE session may change the template set,
which is typically requested by an end-user through User Interface.
If the end-users need to know what templates are available and the
current template set status, they may issue the GET TMPL message.
The following steps are performed in order to change the templates:
A) The server MUST retrieve from CRANE client the template set that
requires change by issuing GET TMPL message. The server can issue a
GET TMPL even if it has not yet issued a START message.
B) After received a GET TMPL message, the client sends back a GET
TMPL RSP message with the requested data.
C) The server makes the necessary changes to the templates and sends
back a START NEGOTIATION message. This message triggers the CRANE
client to inquire about changes made by the CRANE server.
D) After received a START NEGOTIATE message, the client MUST respond
with START NEGOTIATE ACK message followed by a TMPL DATA message.
From this point on, the template negotiation process starts.
Zhang & Elkin Informational [Page 11]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
2.7 Flow Control
After templates have been deployed, DATA messages start to arrive at
the primary CRANE server (the operational one with the highest
priority within the CRANE session). Each DATA message contains a
Data Sequence Number (DSN). The primary CRANE server MUST accept the
data as long as it is in-sequence. Out-of-sequence DATA messages
should be discarded.
The CRANE server detects the start of accounting data when it
receives the first DATA message either after startup or after a
server transition. The first DATA message MUST have the 'S' bit
('DSN Synchronize' bit) set by the CRANE client. Upon reception of
the message with initial DSN, the server MUST accept all in-sequence
DATA messages. The DSN MUST be incremented by 1 for each new DATA
message originated from the client.
A CRANE server MUST acknowledge the reception and correct processing
of DATA messages by sending DATA ACK messages. The DATA ACK MUST
contain the DSN of the last processed in-sequence DATA message. If
the CRANE server receives an Out Of Sequence DATA message, it MUST
also send a DATA ACK message. It will trigger an immediate
retransmission of unacknowledged records.
The CRANE client is responsible for delivering all the records. In
the case of a redundant server configuration, there could be a
scenario when one server does not receive all the records but another
redundant CRANE server for the same mediation system receives the
rest of the records. For example, server #1 could receive records
3042-3095 and then 3123-..., with server #2 receiving records 3096-
3122. It is the sender's responsibility to deliver all the records,
in-sequence, but not necessarily to the same server.
The billing/mediation system eventually receives all the records,
possibly through more than one CRANE server. The CRANE client MUST
convey all the records it received to the billing/mediation system.
This MAY result in duplicate records in the billing/mediation
system. In this case, the DSN MUST be used to remove duplicates. To
aid the process of duplicate removal, whenever a record is re-sent to
another server, its 'Duplicate' bit MUST be set to suggest that this
record might be a duplicate.
Implementation Note:
When the amount of unacknowledged records reaches a threshold, a
timer should be started. When the timer expires, all the
unacknowledged records should be transmitted to an alternate
Zhang & Elkin Informational [Page 12]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
server with 'D' bit set in the DATA message; if alternate servers
are not available, the records should be retransmitted.
The CRANE flow control also supports redundant server
configuration. A server MUST send a START message in order to
move to the 'ready' state. In the 'ready' state, the server can
receive and process CRANE messages. To leave the 'ready' state
and stop the message flows from the client, the server should send
a STOP message to the client.
2.8 The CRANE Client Query Messages
A CRANE server may query a CRANE client's status by sending query
messages after it has established a session with the client. A CRANE
client that is connected to the server MUST respond with response
messages. All the Query Messages MUST be initiated by a CRANE
server. The CRANE protocol defines three such Query Message pairs,
they are:
Get Session (GET SESS)
Get Session Response (GET SESS RSP)
Get Template (GET TMPL)
Get Template Response (GET TMPL RSP)
Status Request (STATUS REQ)
Status Response (STATUS RSP)
All the query messages incorporate a Request ID field for tagging
purposes and matching requests and responses. This field contains a
16 bit counter incremented with every request and is set by the
initiator of the request. Along with the CRANE server's IP address
and port number, this constitutes a unique identifier for a request.
This value MUST be copied to Request ID field in the response message
in order to associate a specific response with a request.
The CRANE client SHOULD collect and send out meta-data about the data
collected (counters, statistics, etc.). This is done by creating
status templates, which are treated like any other template, with the
exception that these templates are marked with a /'Status' bit.
Status templates are used with the set of STATUS REQ and STATUS RSP
messages. A server MAY issue a STATUS REQ to a CRANE client and
receive a STATUS RSP message with the requested data.
2.9 CRANE Sessions
A CRANE client MAY deliver accounting data to different
mediation/billing systems by establishing different CRANE sessions.
Zhang & Elkin Informational [Page 13]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Each session MAY consist of several CRANE servers in a redundant
configuration. The session ID imbedded in all the CRANE messages
enables the correct association of CRANE sessions with CRANE users.
All the CRANE processes (e.g., template negotiation, configuration,
flow control, etc.) should be carried out in the same way in a multi
session scenario.
Each session has its set of templates (these may be the same
templates, but the keys could be enabled or disabled differently).
The sessions are configured in the NE, each with a different session
name with associated Session IDs. The session ID is carried in each
message to associate the message with a specific session.
A CRANE server MAY take part in different sessions. When configuring
a server, it needs to know the sessions in which it participates.
The server can issue a GET SESS message to receive a list of relevant
sessions.
3 CRANE Message Format
A summary of the CRANE protocol message format is shown below. A
CRANE message consists of an 8 octet message header; it is followed
by a variable length message payload that is aligned to 32 bit
boundary. Some of the messages do not have the CRANE Message Payload
part. The fields are in network byte order and transmitted from left
to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version |Message ID(MID)| Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ CRANE Message Payload ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Version: 8 bit unsigned integer
The Version field indicates the supported CRANE protocol
implementation. This field MUST be set to 1 to indicate the CRANE
protocol Version 1.0. CRANE protocol Version 1.0 only supports
Ipv4 addressing; however, it can be used to transfer information
related to Ipv6 flows.
Zhang & Elkin Informational [Page 14]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message ID (MID): 8 bit unsigned integer
The Message ID field identifies the type of the message. The
message IDs defined by CRANE Version 1 are:
Message Name Short Name Message ID
--------------------- --------------- ------------
Reserved 0x00
Flow Start START 0x01
Flow Start Acknowledge START ACK 0x02
Flow Stop STOP 0x03
Flow Stop Acknowledge STOP ACK 0x04
Connect CONNECT 0x05
Template Data TMPL DATA 0x10
Template Data Acknowledge TMPL DATA ACK 0x11
Final Template Data FINAL TMPL DATA 0x12
Final Template Data Ack. FINAL TMPL DATA ACK 0x13
Get Sessions GET SESS 0x14
Get Sessions Response GET SESS RSP 0x15
Get Template GET TMPL 0x16
Get Template Response GET TMPL RSP 0x17
Start Negotiation START NEGOTIATE 0x18
Start Negotiation Ack. START NEGOTIATE ACK 0x19
Data DATA 0x20
Data Acknowledge DATA ACK 0x21
Error ERROR 0x23
Status Request STATUS REQ 0x30
Status Response STATUS RSP 0x31
Session ID: 8 bit unsigned char
The Session ID field identifies the session with which the message
is associated. The session ID is ignored in the case of GET SESS
and GET SESS RSP messages. More details about session can be
found in Section 2.9.
Message Flags: 8 bit unsigned char
The Message Flags field can be used to identify options associated
with the message. For CRANE Version 1.0, all the flags are
reserved; unless otherwise specified, the flags are set to zero on
transmit and are ignored on receipt.
Zhang & Elkin Informational [Page 15]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Length: 32 bit unsigned integer
The Message Length field is the total length of the CRANE message
in octet including the header.
4 CRANE Messages
This section defines CRANE mandatory messages. They MUST be
supported by any CRANE protocol implementation.
4.1 Flow Start (START)
Description
The Flow Start message is sent from a CRANE server to a CRANE
client to indicate that the CRANE server is ready to receive CRANE
messages.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x01 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2 Flow Start Acknowledge (START ACK)
Description
The Flow Start Acknowledge message is sent by a CRANE client to
acknowledge the reception of a START message from a specific CRANE
server. It is sent only to that server to indicate that the
client considers it ready to receive CRANE messages.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x02 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Client Boot Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Zhang & Elkin Informational [Page 16]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Client Boot Time: 32 bit unsigned integer
The Client Boot Time field is the timestamp of the last client
startup in seconds from 1970. This field can be combined with the
DSN and the client's IP address to serve as a system wide unique
record identifier.
4.3 Flow Stop (STOP)
Description
The Flow Stop message is sent from a CRANE server to a CRANE
client to instruct it to stop sending data (to that server). The
STOP message does not disconnect the server; it only stops the
CRANE client from sending "DATA" messages.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x03 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.4 Flow Stop Acknowledge (STOP ACK)
Description
The Flow Stop Acknowledgement message acknowledges the STOP
message issued by a CRANE server.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x04 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Zhang & Elkin Informational [Page 17]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
4.5 Connect (CONNECT)
Description
The CONNECT message is sent from a CRANE server to a CRANE client
to identify itself. The message MUST be the first message sent
over a transport layer connection between the server and the
client.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x05 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Server Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Server Port | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Server Address: 32 bit unsigned integer
The Server Address field is the server's IP address (IPV4).
Server Port: 16 bit unsigned integer
The Server Port field is the server's port number for the
transport layer (the port number specified here doesn't
necessarily have to match the port number used by the transport
layer)
4.6 Template Data (TMPL DATA)
Description
A CRANE client sends the Template Data message to a CRANE server
after a START or a START NEGOTIATE message was received from the
server. The message MUST contain all the templates that are going
to be used for the session. It SHOULD also include the template
for the status records (See section 2.8)
The receiving CRANE server MUST acknowledge the message by sending
either a TMPL DATA ACK (if template changes are needed) or a FINAL
TMPL DATA ACK message. For more information, see section 2.5.
Zhang & Elkin Informational [Page 18]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x10 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Config ID | Flags |E| Number of Templates |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Template Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ... ... ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Template Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Configuration ID (Config. ID): 8 bit unsigned char
The Configuration ID field identifies the version number
associated with a template set. Changes to any of the templates
would result in a new template version, and the version number
would be incremented by one. An implementation SHOULD handle
rollovers of the version number.
Flags: 8 bit unsigned char
The Flags field identifies any options associated to the message.
The flag defined by the CRANE Version 1 is:
The 'E' bit indicates the transmission order of the "DATA"
messages. If the field is set to 1, data is in big endian format;
otherwise, little endian format is used.
Number of Templates: 16 bit unsigned integer
The Number of Templates field is the number of Templates (a
template is described by a Template Block) specified by the
message.
Zhang & Elkin Informational [Page 19]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Template Block
The Template Block field is of variable length and aligned to 32
bit boundary. It is the specification of a template.
Template Block Format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID | Number of Keys |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template Flags |T| Description Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template Block Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Description ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ... ... ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Template ID: 16 bit unsigned integer
The Template ID field identifies a specific template.
Number of Keys: 16 bit unsigned integer
The Number of Keys field is the number of keys included in the
template.
Template Flags: 16 bit unsigned integer
The Template Flags field is composed of flags that indicate
different attributes of the template. In CRANE Version 1.0, only
the 'T' bit is defined, other bits in the field SHOULD be set to
zero by the sender and ignored by the receiver.
Zhang & Elkin Informational [Page 20]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
The 'T' bit ('Status' bit) indicates that the template is a status
template that is used by the STATUS RSP message only. See section
2.8 for more details.
Description Length: 16 bit unsigned integer
The Description Length field is the length of the Description
field. If no description is supplied, the length MUST be 0.
Template Block Length: 32 bit unsigned integer
The Template Block Length is the length of the template block in
octets.
Description: Variable length unsigned char
The Description field contains the text description of the
template (e.g., "Aggregated by interface and ToS bits"). It is a
variable length field of up to 64Kb long, and padded with 0 to the
next 32 bit boundary.
Key Block
A key Block contains the specification of a key within a template.
Key Block Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Type ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Attribute Vector |K|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Key ID: 32 bit unsigned integer
The Key ID field identifies the key within a template. See
section 2.4 for more details.
Key Type ID: 16 bit unsigned integer
The Key Type ID field specifies the data type of the key.
Zhang & Elkin Informational [Page 21]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
The fixed length data types are defined as following:
Data Type Data Type ID
--------------------- --------------
Boolean (1) 0x0001
Unsigned Integer8 0x0002
Signed Integer8 0x0003
Unsigned Integer16 0x0004
Signed Integer16 0x0005
Unsigned Integer32 0x0006
Signed Integer32 0x0007
Unsigned Integer64 0x0008
Signed Integer64 0x0009
Float (2) 0x000a
Double (2) 0x000b
IP address (Ipv4) 0x0010
IP address (Ipv6) 0x0011
Time_SEC (3) 0x0012
Time_MSEC_64(4) 0x0013
Time_USEC_64 (5) 0x0014
Time_MSEC_32 (6) 0x0015
Time_USEC_32 (7) 0x0016
The variable length data types are defined as following:
String (8) 0x400c
Null Terminated String 0x400d
UTF-8 String 0x400e
UTF-16 String 0x400f
Arbitrary Data (BLOB) (9) 0x4015
(1) Boolean is represented as a single octet holding 0 for a
value of FALSE and 1 for a value of TRUE.
(2) Float and Double are single and double precision floating
point numbers that comply with the IEEE-754 standard.
(3) Time_SEC is a 32 bit value, most significant octet first
- seconds since 00:00:00 GMT, January 1, 1970.
(4) Time_MSEC_64 is a 64 bit value, most significant octet
first - milliseconds since 00:00:00 GMT, January 1, 1970.
(5) Time_USEC_64 is a 64 bit value, most significant octet
first - microseconds since 00:00:00 GMT, January 1, 1970.
Zhang & Elkin Informational [Page 22]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
(6) Time_MSEC_32 is a 32 bit value, most significant octet
first - milliseconds since 00:00:00 GMT, January 1, 1970.
(7) Time_USEC_32 is a 32 bit value, most significant octet
first - microseconds since 00:00:00 GMT, January 1, 1970.
(8) String is prefixed by a 32 bit length field that
indicates the length of the string, and followed by ASCII
codes of the string characters. This representation MUST
only be used for encoding data records in a "DATA" message.
(9) The arbitrary data is prefixed by a 32 bit length field
and followed by the data in binary format.
Key Attribute Vector: 32 bit unsigned integer
The Key Attribute Vector field indicates different attributes of
the key. In CRANE Version 1, only the 'K' bit is defined, other
bits in the field SHOULD be set to zero by the sender and ignored
by the receiver.
The 'K' bit ('Disabled bit') is set to 1 when the key is disabled
in this template.
4.7 Template Data Acknowledge (TMPL DATA ACK)
Description
The Template Data Acknowledge message is sent from a CRANE server
to a CRANE client after a TMPL DATA message has been received. It
proposes changes of the templates and/or key status changes
(enable/disable) for the templates.
If a CRANE server wishes to acknowledge reception of TMPL DATA
without changes, it MUST respond with the FINAL TMPL DATA ACK
message.
Zhang & Elkin Informational [Page 23]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x11 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Config. ID | Reserved | Number of Template Changes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Template Change Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ... ... ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Template Change Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Configuration ID (Config. ID): 8 bit unsigned char
See Section 4.6. The value MUST be identical to the Config. ID
field of the acknowledged TMPL DATA message.
Number of Template Changes: 16 bit unsigned integer
The Number of Template Changes field is the number of changed
Templates (a changed template is described by a Template Change
Block) specified by the message.
Zhang & Elkin Informational [Page 24]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Template Change Block
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID | Number of Keys |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ... ... ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Template ID: 16 bit unsigned integer
See Section 4.6.
Number of Keys: 16 bit unsigned integer
See Section 4.6.
Key Block
See Section 4.6, only relevant keys are described.
4.8 Final Template Data (FINAL TMPL DATA)
Description
The Final Template Data message is sent by a CRANE client to all
the CRANE servers in a session, to convey the finalize templates.
It is similar to the TMPL DATA message, with the only difference
that a server must accept the templates in this message.
Message Format
Identical to the TMPL DATA (see section 4.6)
Message ID (MID)
0x12 Final Template Data
Zhang & Elkin Informational [Page 25]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
4.9 Final Template Data Acknowledge (FINAL TMPL DATA ACK)
Description
The CRANE server acknowledges reception of the TMPL DATA or FINAL
TMPL DATA by sending a Final Template Data Acknowledge message.
It does not carry any changes to the templates. Unlike TMPL DATA
ACK messages, a FINAL TMPL DATA ACK message indicates the
acceptance of the templates for the session. A server MAY respond
with this message to a TMPL DATA (if it does not want any changes
in the templates). A server MUST respond with this message to a
FINAL TMPL DATA.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x13 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Config. ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Configuration ID: 8 bit unsigned char
See Section 4.6. This field MUST copy the configuration ID from
the acknowledged message.
4.10 Get Sessions (GET SESS)
Description
The Get Sessions message is sent by a CRANE server to a CRANE
client to query what are the sessions it should participate. This
is typically done just before a UI configuration of the CRANE
client's templates. As each session has its own set of templates,
there is a need to know the server's participation of all the
sessions.
The Session ID field in the CRANE message header MUST be ignored
by the receiver.
Zhang & Elkin Informational [Page 26]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x14 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Request ID: 16 bit unsigned integer
The Request ID field identifies the specific request issued by the
server. The same Request ID MUST be placed in the responding
message in order to associate it with the request.
4.11 Get Sessions Response (GET SESS RSP)
Description
The Get Sessions Response message is sent by a CRANE client to a
CRANE server as a reply to a GET SESS request. The message MUST
contain all the information related to any session with which the
requesting server is associated.
The Session ID field in the common message header MUST be ignored
by the receiver.
Zhang & Elkin Informational [Page 27]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x15 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request ID | Number of Sessions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor String Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| |
~ Vendor String ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Session Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ... ... ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Session Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Request ID: 16 bit unsigned integer
See Section 4.10.
Number of Sessions: 16 bit unsigned integer
The Number of Sessions field is the number of session blocks in
the message.
Vendor String Length: 16 bit unsigned integer
The Vendor String Length field is the length of Vendor String
field in octet. The field limits vendor strings to 64Kb long. If
no such string is supplied, the length MUST be set to 0.
Zhang & Elkin Informational [Page 28]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Vendor String: Variable length unsigned char
The Vendor String field is a variable length field. It identifies
the vendor that created the session. It MUST be padded with 0 to
the next 32 bit boundary. The information differentiates similar
templates from different vendors. The actual format of the
information is application specific and outside the scope of this
document.
Session Block
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session ID | Reserved | Session Name Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Description Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Session Name ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Session Description ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Session ID: 8 bit unsigned char
See Section 3.
Session Name Length: 16 bit unsigned integer
The Session Name Length field is the length of the Session Name
field. The field limits the session name strings to 64 Kb long.
As a name is mandatory to differentiate between sessions, this
field MUST NOT be 0.
Session Description Length: 16 bit unsigned integer
The Session Description Length field is the length of a session
description. The field limits the session description to 64Kb
long. If no such Description is supplied, the length MUST be set
to 0.
Zhang & Elkin Informational [Page 29]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Session Name: Variable length unsigned char
The Session Name field is the name for a session, which MAY be
displayed to end-users. It MUST be padded with 0 to the next 32
bit boundary. Session Name MUST be unique within a CRANE client.
This field is mandatory and MUST be a part of any Session Block.
Session Description: Variable length unsigned char
The Session Description field is the text description of a
session; it could be displayed to end-users. It MUST be padded
with 0 to the next 32 bit boundary.
4.12 Get Templates (GET TMPL)
Description
The Get Templates message is sent by a CRANE server to a CRANE
client to query templates in a session.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x16 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Request ID: 16 bit unsigned integer
See Section 4.10.
4.13 Get Templates Response (GET TMPL RSP)
Description
The Get Templates Response message is sent by a CRANE client to a
CRANE server as a response to a GET TMPL message. The message
SHOULD contain all templates available for the specific session.
Zhang & Elkin Informational [Page 30]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x17 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request ID | Number of Templates |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Template Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ... ... ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Template Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Request ID: 16 bit unsigned integer
See Section 4.10.
Number of Templates: 16 bit unsigned integer
See Section 4.6.
Template Block
Same as the template block defined in the TMPL DATA message (see
Section 4.6). However, Extended Key Blocks MUST be used instead
of Key Blocks. Extended key Block field provides extensive
informational data that MAY be displayed to end-users.
Extended Key Block
The Extended Key Block field provides comprehensive information
about a key.
Zhang & Elkin Informational [Page 31]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Extended Key Block Format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Type ID | Key Name Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Label Length | Key Help Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Name ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Label ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Help ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Attribute Vector |K|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Key ID: 32 bit unsigned integer
Same as section 4.6.
Key Type ID: 16 bit unsigned integer
Same as section 4.6.
Key Name Length: 16 bit unsigned integer
The Key Name Length field is the length of the Key Name field.
The field limits Key Name strings to 64 Kb long. As a name is
mandatory to a key, this field MUST NOT be 0.
Key Label Length: 16 bit unsigned integer
The Key Label Length field is the length of the Key Label field.
The field limits Key Label strings to 64 Kb long. Length of 0
means that the Label field is to be skipped.
Zhang & Elkin Informational [Page 32]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Key Help Length: 16 bit unsigned integer
The Key Help Length field is the length of the Key Help field.
The field limits Key Help strings to 64 Kb long. Length of 0
means that the Help field is to be skipped.
Key Name: Variable length unsigned char
The Key Name field is the name for the key, which could be
displayed to end users. It MUST be padded with 0 to the next 32
bit boundary. Key Name MUST be unique (within the template) and
case sensitive. This field is mandatory and MUST be a part of any
Extended Key Block.
Key Label: Variable length unsigned char
The Key Label field is a descriptive label, which could be
displayed to end users concerning this key. It MUST be padded
with 0 to the next 32 bit boundary. This field SHOULD be a part
of any Extended Key Block.
Key Help: Variable length unsigned char
The Key Help field is any Help string that could be displayed to
end users concerning this key. It MUST be padded with 0 to the
next 32 bit boundary. This field MAY be a part of any Extended
Key Block.
Key Attribute Vector: 32 bit unsigned integer
Same as section 4.6.
4.14 Start Negotiation (START NEGOTIATE)
Description
The Start Negotiation message is sent by a CRANE server after the
configuration process has completed. The message should initiate
template negotiation by the client with all CRANE servers in a
session. The CRANE server MAY re-send this message up to 3 times
with repeat interval of 5 seconds unless it is acknowledged by the
CRANE client. Otherwise, the CRANE user will be informed. The
client should send TMPL DATA message to the servers after
acknowledged the message.
Zhang & Elkin Informational [Page 33]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x18 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.15 Start Negotiation Acknowledge (START NEGOTIATE ACK)
Description
The Start Negotiation Acknowledge message MUST be sent by a CRANE
client to the server to acknowledge the reception of the START
NEGOTIATE message.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x19 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.16 Data (DATA)
Description
The DATA message carries actual data records from a CRANE client
to a CRANE server. A data record is a structured collection of
fields that matches a specific template.
Zhang & Elkin Informational [Page 34]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x20 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID | Config. ID | Flags |D|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sequence Number (DSN) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Record Data ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Template ID: 16 bit unsigned integer
See Section 4.6.
Configuration ID: 8 bit unsigned char
See Section 4.6. The Config. ID field can prevent out-of-the-blue
messages with outdated templates arriving and erroneously
processed. A server MAY keep a short history of templates in
order to cope with this scenario.
Flags: 8 bit unsigned char
The Flags field is composed of flag bits that indicate processing
requirements of the data records. The CRANE Version 1 defined two
flags for these purposes. Unless otherwise specified, the other
flags are set to zero on transmit and are ignored on receipt.
The following flags are defined in CRANE Version 1:
The 'D' bit ('Duplicate' bit): It is set for records that are
re-sent to an alternate server after a server transition occurs.
When the same records are sent to different servers, there is a
possibility that duplicated data exists. The Status of the 'D'
bit will help the billing/mediation system to perform
de-duplication if desired.
Zhang & Elkin Informational [Page 35]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
The 'S' bit ('DSN Synchronize' bit): When set, it indicates that
the record is the first one received by the server after starting
(or restarting) of data transmission to this server. The server
MUST set the initial DSN to the DSN specified in the record. The
flag is set to zero by default.
Data Sequence Number: 32 bit unsigned integer
The Data Sequence Number field is the record sequence number used
for preserving data orders and detecting data losses. The DSN
MUST be incremented by one for each new record transmitted. The
selection of the initial DSN number is implementation specific.
Record Data: Variable Length unsigned octets
The Record Data field carries the actual accounting/billing data
that is structured according to the template identified by the
Template ID field.
4.17 Data Acknowledge (DATA ACK)
Description
The Data Acknowledgement message is sent from a CRANE server to
acknowledge receipt of records. It acknowledges the maximal in-
sequence DSN received.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x21 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Config. ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Sequence Number: 32 bit unsigned integer
See Section 4.16. It MUST be DSN of the last in-sequence record
that was received by the server.
Zhang & Elkin Informational [Page 36]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Configuration ID: 8 bit unsigned char
See Section 4.16.
4.18 Error (ERROR)
Description
The Error message MAY be issued by either a CRANE server or
client. It indicates an error condition that was detected by the
sender.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x23 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code | Description Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Description ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Timestamp: 32 bit unsigned integer
The Timestamp field is a timestamp in seconds since 00:00:00 GMT,
January 1, 1970.
Error Code: 16 bit unsigned integer
The Error Code field is a code assigned to an error condition.
The following error codes are defined in CRANE Version 1:
Error Condition Error Code
----------- --------------
Unknown 0
Zhang & Elkin Informational [Page 37]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Description Length: 16 bit unsigned integer
The Description Length field is the length of the Description
field. The field limits Description strings to 64 Kb long.
Length of 0 means that the Description field is to be skipped.
Description: Variable Length unsigned char
The Description field is a text description that allows the sender
to provide more detailed information about the error condition.
It MUST be padded with 0 to the next 32 bit boundary.
4.19 Status Request (STATUS REQ)
Description
CRANE servers MAY inquire general operation status of a client by
sending the Status Request message. The status information SHOULD
include a collection of states, counters, accumulators of the data
collection functions that reside with the client. The status MAY
include more information about the CRANE client itself.
The status reporting mechanism relies on the status template of a
session. It is determined similarly as other templates. Without
a determined status template, no status information can be
delivered.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x30 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.20 Status Response (STATUS RSP)
Description
The Status Response message contains a status report that MUST be
compatible with the status template of the session. It is
client's response to a STATUS REQ message from a server.
Zhang & Elkin Informational [Page 38]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | MID=0x31 | Session ID | Message Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID | Reserved |Config. ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Record Data ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Template ID: 16 bit unsigned integer
See Section 4.6.
Configuration ID: 8 bit unsigned integer
See Section 4.6. The version is needed here to prevent
out-of-the-blue messages with outdated templates arriving and
erroneously processed. A server MAY keep a short history of
templates in order to cope with this scenario.
Record Length: 32 bit unsigned integer
The Record Length field is the length of the Record Data field in
octets.
Record Data: Variable Length unsigned octets
The Record Data field contains the status data that complies with
the status template. For more details see section 2.4
5 Protocol Version Negotiation
Since the CRANE protocol may evolve in the future and it may run over
different transport layers, a transport neutral version negotiation
mechanism running over UDP is defined. A CRANE server MAY inquire a
CRANE client about the CRANE protocol version and transport layer
support by sending a UDP packet on an agreed UDP port. The client
MUST respond to this request with a UDP packet carrying the protocol
Zhang & Elkin Informational [Page 39]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
version, the transport type and the port number used for the specific
transport. The Protocol Version Negotiation is optional for CRANE
Version 1.
The CRANE server sends the following message to query the client's
protocol support.
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Server Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Server Boot Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 'C' | 'R' | 'A' | 'N' |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Server Address:
The Server Address field is the IP address (Ipv4) of the CRANE
server.
Server Boot Time
The Server Boot Time field is the timestamp of the last server
startup in seconds from 1970.
'C', 'R', 'A', 'N':
The 'C', 'R', 'A', 'N' fields are ASCII encoded characters to
identify the CRANE server.
Zhang & Elkin Informational [Page 40]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
The client's reply to a version negotiation request MUST comply with
the following structure:
Message Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Default Protocol Info |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Protocols Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Protocols Info |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... Additional Protocols Info ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Protocols Info |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Default Protocol Info:
The Default Protocol Info field contains information of the
default protocol supported by the client. The field is structured
as a Protocol Info Block described below.
Additional Protocols Count: 32 bit unsigned integer
The Additional Protocols Count field specifies the number of
additional protocols supported by the client. In the case that
only the default protocol is supported, the field MUST be set to
0.
Additional Protocols Info:
The Additional Protocol Info field is an array of Protocol Info
Blocks (described below) contain information about additional
protocols supported by the client.
Zhang & Elkin Informational [Page 41]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
Protocol Info Block
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Number | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Transport Type: 32 bit unsigned integer
1 - TCP, 2 - SCTP
Protocol Version: 32 bit unsigned integer
Version number of the CRANE protocol supported over the specific
transport layer, the current version is 1.
Port Number: 16 bit unsigned integer
Port number (either SCTP or TCP port) used for the protocol
6 Security Considerations
The CRANE protocol can be viewed as an application running over a
reliable transport layer, such as TCP and SCTP. The CRANE protocol
is end-to-end in the sense that the CRANE messages are communicated
between clients and servers identified by the host address and the
transport protocol port number. Before any CRANE sessions can be
initiated, a set of CRANE servers' addresses should be provisioned on
a CRANE client. Similarly, a CRANE server maintains a list of CRANE
clients' address with which it communicates. The provisioning is
typically carried out securely using a network management system; in
this way, the CRANE end-points can be authenticated and authorized.
As this scheme is static, without additional security protections the
CRANE protocol is vulnerable to attacks such as address spoofing.
The CRANE protocol itself does not offer strong security facilities;
therefore, it cannot ensure confidentiality and integrity of CRANE
messages. It is strongly recommended that users of the CRANE
protocol evaluate their deployment configurations and implement
appropriate security policies. For example, if the CRANE protocol is
deployed over a local area network or a dedicated connection that
Zhang & Elkin Informational [Page 42]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
ensure security, no additional security services or procedures may be
required; however, if CRANE clients and servers are connected through
the Internet, lower layer security services should be invoked.
To achieve a strong security protection of communications between
CRANE clients and servers, lower layer security services are strongly
recommended. The lower layer security services are transparent to
the CRANE protocols. Security mechanisms may be provided at the IP
layer using IPSEC [6], or it may be implemented for transport layer
using TLS [7]. The provisioning of the lower layer security services
is out of the scope of this document.
7 References
[1] Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
Authentication Dial In User Service (RADIUS)", RFC 2865, June
2000.
[2] Calhoun, P., "DIAMETER Base Protocol", Work in Progress.
[3] Calhoun, P., et. al., "DIAMETER Framework Document", Work in
Progress.
[4] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer,
H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
"Simple Control Transmission Protocol", RFC 2960, October 2000.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[6] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.
[7] Dierks, T. and C. Allen, "The TLS Protocol, Version 1.0", RFC
2246, January 1999.
8 Acknowledgments
Special thanks are due to Tal Givoly, Limor Schweitzer for conceiving
the work, and Nir Pedhatzur, Batya Ferder, and Peter Ludemann from
XACCT Technologies for accomplishing the first CRANE protocol
implementation.
Thanks are also due to Nevil Brownlee for his valuable comments on
the work, as well as the IETF IPFIX WG.
Zhang & Elkin Informational [Page 43]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
9 Authors' Addresses
Kevin Zhang
10124 Treble Court
Rockville, MD 20850
U.S.A.
Phone +1 301 315 0033
EMail: kevinzhang@ieee.org
Eitan Elkin
XACCT Technologies, Ltd.
www.xacct.com
12 Hachilazon St.
Ramat-Gan, Israel 52522
Phone +1 972 3 576 4111
EMail: eitan@xacct.com
Zhang & Elkin Informational [Page 44]
RFC 3423 XACCT's CRANE Protocol Specification November 2002
10 Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Zhang & Elkin Informational [Page 45]