CRANE, Common Reliable Accounting for Network Element

Protocol suite:	TCP/IP.
Type:	Application layer protocol.
Port:	TBD (SCTP, TCP).
SNMP MIBs:
Working groups:

RFC 3423:

TCP and SCTP 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 is the preferred way to transmit CRANE messages.

MAC header	IP header	SCTP header	CRANE header	Data :::
MAC header	IP header	TCP header	CRANE header	Data :::

CRANE header:

00	08	16	24
Version	Type	Session ID	Flags
Length
Data :::

Version. 8 bits.
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.

Type. 8 bits.
Identifies the type of the message.

Type	Description
0x00	reserved.
0x01	START, Flow Start.
0x02	START ACK, Flow Start Acknowledge.
0x03	STOP, Flow Stop.
0x04	STOP ACK, Flow Stop Acknowledge.
0x05	CONNECT, Connect.
0x10	TMPL DATA, Template Data.
0x11	TMPL DATA ACK, Template Data Acknowledge.
0x12	FINAL TMPL DATA, Final Template Data.
0x13	FINAL TMPL DATA ACK, Final Template Data Ack.
0x14	GET SESS, Get Sessions.
0x15	GET SESS RSP, Get Sessions Response.
0x16	GET TMPL, Get Template.
0x17	GET TMPL RSP, Get Template Response.
0x18	START NEGOTIATE, Start Negotiation.
0x19	START NEGOTIATE ACK, Start Negotiation Ack.
0x20	DATA, Data.
0x21	DATA ACK, Data Acknowledge.
0x23	ERROR, Error.
0x30	STATUS REQ, Status Request.
0x31	STATUS RSP, Status Response.

Session ID. 8 bits.
Identifies the session with which the message is associated. This field is ignored in the case of GET SESS and GET SESS RSP messages.

Flags. 8 bits.
Used to identify options associated with the message. For CRANE Version 1.0, all the flags are reserved. The flags are set to zero on transmit and are ignored on receipt.

Length. 32 bits.
Total length of the CRANE message in bytes including the header.

Data. Variable length.

Glossary:

CRANE Session.
(RFC 3423) 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.

Data Record.
(RFC 3423) 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.

DSN, Data Sequence Number.
(RFC 3423) An accounting Data Record level sequence number, which is attached to all data messages to facilitate reliable and in-sequence delivery.

Server priority.
(RFC 3423) 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.

Template.
(RFC 3423) Defines the structure of any types of Data Record, and specifies the data type, meaning, and location of the fields in the record.

RFCs:

[RFC 3423] XACCT's Common Reliable Accounting for Network Element (CRANE) Protocol Specification Version 1.0.

Defines CRANE version 1.

[RFC 3955] Evaluation of Candidate Protocols for IP Flow Information Export (IPFIX).