One document matched: draft-leinen-ipfix-tcp-00.txt
IP Flow Information Export Working S. Leinen
Group SWITCH
Internet-Draft July 12, 2004
Expires: January 10, 2005
IP Flow Information Export (IPFIX) Over TCP
draft-leinen-ipfix-tcp-00
Status of this Memo
By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with
RFC 3668.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on January 10, 2005.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This documents describes how the IP Flow Information Export (IPFIX)
protocol should be mapped to the Transmission Control Protocol (TCP).
1. Introduction
IP Flow Information Export (IPFIX) [1] is a protocol to convey
accounting information from an exporter to a collector. It has been
proposed that the protocol operate over the Stream Control
Transmission Protocol [7] with the Partial Reliability extension
Leinen Expires January 10, 2005 [Page 1]
Internet-Draft IPFIX over TCP July 2004
(SCTP-PR) [8].
In this document, we specify an alternate mapping of IPFIX to TCP
[2], which can be used when SCTP-PR isn't available, and reliable
transmission and/or congestion handling are required.
2. OPEN ISSUES
2.1 Handshake
Should we introduce a handshake sequence at the start of the
connection? A simple ASCII-based handshake could be used to request
TLS.
2.2 TLS
It would make sense to add TLS support even in the absence of a
handshake. It would be the responsibility of the collector
(connection initiator) to know whether TLS setup is required.
2.3 Directionality
The fact that the connection is initiated by the collector is a
departure from the way it is done in the SCTP mapping. Personally I
find it more natural this way. There are not very many practical
differences anyway. Collector-initiated connections are easier to
handle when the collector is behind a NAT or typical firewall, while
exporter-initiated connections are easier when the exporter is behind
a NAT or firewall. Collector-initiated connections are faster to
restart when a collector terminates, exporter-initated connections
are faster to restart when an exporter restarts.
One difference is that in the case of multiple observation domains,
one may want to establish parallel IPFIX export connections. The
current definition makes this difficult. Perhaps the most natural
way to do this would be to have the exporter initiate the connection,
require the collector to handle multiple connections, and allow the
exporter to establish one connection per observation domain.
3. Operation
The following sections describe how an IPFIX-over-TCP connection is
created, how IPFIX data is transferred over it, and how a connection
is to be terminated. In the following, the term "exporter" refers to
an IPFIX exporting process, while a "collector" refers to an IPFIX
collecting process.
Leinen Expires January 10, 2005 [Page 2]
Internet-Draft IPFIX over TCP July 2004
3.1 Connection Establishment
The IPFIX collector initiates a TCP connection to the exporter. By
default, the exporter listens for connections on TCP port XXXX (to be
assigned by IANA). It MUST be possible to configure the exporter to
listen on a different TCP port.
An exporter MAY support more than one active connection to different
collectors (including the case of different collecting processes on
the same host).
It MUST be possible to configure, on an exporter, which collector(s)
are allowed to establish a connection. It SHOULD be possible to
configure this in terms of strong identities such as IKE [6]
public-key certificates or pre-shared keys. An exporter SHOULD
detect and log unauthorized connection attempts.
3.2 Data Transmission
Once a TCP connection is established, the exporter starts sending
IPFIX messages to the collector.
3.2.1 IPFIX Message Encoding
IPFIX Messages are sent over the TCP connection without any special
encoding. The LENGTH field in the message header defines the end of
each message and thus the start of the next message. This means that
IPFIX messages cannot be interleaved.
The 16-bit LENGTH field limits the length of a message to 65536
octets including the header. A collector MUST be able to handle
message lengths of up to 65536 octets.
If an exporter exports data from multiple observation domain, it
should be careful to choose message lengths appropriately to avoid
head-of-line blocking between different observation domains.
3.2.2 Templates
For each template, the exporter SHOULD send the Template Record
before exporting Data Records that refer to this template.
A collector MUST record all Template and Option Template Records for
the duration of the connection, as an exporter is not required to
re-export templates.
Leinen Expires January 10, 2005 [Page 3]
Internet-Draft IPFIX over TCP July 2004
3.2.3 Congestion Handling
TCP will detect congestion anywhere in the end-to-end path between
the exporter and the collector, and limit the transfer rate
accordingly. Every time an IPFIX exporter has flow data to export,
but notices that transmission to TCP is temporarily impossible
("would block"), it basically has two possibilities: Either it can
wait until sending is possible again, or it can decide to drop the
flow export data. In the latter case, the dropped export data MUST
be accounted for, so that the amount of dropped export data can later
be exported in an option data record.
When an exporter finds that the rate at which flow records should be
exported is consistently higher than the rate at which TCP permits to
send, it SHOULD adapt the metering process so that it generates a
lower amount of data, for example by increasing the sampling
interval, or by increasing the amount of aggregation. If it does
this, the exporter SHOULD periodically attempt to switch back to the
original metering configuration when congestion subsides.
3.3 Connection Release
When an exporter has no more data to send, it SHOULD close the TCP
connection normally.
When a collector no longer wants to receive IPFIX messages, it SHOULD
close its end of the connection. The collector SHOULD continue to
read IPFIX messages until the exporter has closed its end.
When an exporter detects that the TCP connection to the collector is
broken, it MUST continue to listen for a new connection.
When a collector detects that the TCP connection to the exporter is
broken, it SHOULD try to re-establish the connection. Connection
timeouts and retry schedules SHOULD be configurable. In the default
configuration, a collector MUST NOT attempt to establish a connection
more frequently than once per minute.
4. Security Considerations
In the current proposal, there is no handshake protocol once a TCP
connection is established, so negotiation-based transport-layer
security protocols such as TLS [9] cannot be used in a
straightforward manner to ensure authenticity and confidentiality.
Exporters and collectors MUST implement IPSEC [3] with the
Authentication Header (AH) [4] to ensure authenticity of the exporter
and the collector. Exporters SHOULD implement IPSEC Encapsulating
Leinen Expires January 10, 2005 [Page 4]
Internet-Draft IPFIX over TCP July 2004
Security Payload (ESP) [5] to ensure confidentiality of the exported
data. The use of AH and ESP MUST be configurable for each exporter/
collector pair.
Exporters and collectors MUST implement the Internet Key Exchange
(IKE) [6] protocol with pre-shared keys and public-key certificates.
The use of these identities is described in Section 3.1.
5. IANA Considerations
No new registry is required for this specific protocol mapping.
IANA should assign a well-known TCP port number for IPFIX over TCP.
It is recommended that the same well-known port number is used as a
default for the IPFIX over SCTP [1] and IPFIX over UDP mappings.
6. References
6.1 Normative References
[1] Claise, B., "IPFIX Protocol Specifications",
draft-ietf-ipfix-protocol-03 (work in progress), February 2004.
[2] Postel, J., "Transmission Control Protocol", STD 7, RFC 793,
September 1981.
[3] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.
[4] Kent, S. and R. Atkinson, "IP Authentication Header", RFC 2402,
November 1998.
[5] Kent, S. and R. Atkinson, "IP Encapsulating Security Payload
(ESP)", RFC 2406, November 1998.
[6] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)",
RFC 2409, November 1998.
6.2 Informative References
[7] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer,
H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
"Stream Control Transmission Protocol", RFC 2960, October 2000.
[8] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M. and P. Conrad,
"Stream Control Transmission Protocol (SCTP) Partial Reliability
Extension", RFC 3758, May 2004.
Leinen Expires January 10, 2005 [Page 5]
Internet-Draft IPFIX over TCP July 2004
[9] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC
2246, January 1999.
Author's Address
Simon Leinen
SWITCH
Limmatquai 138
P.O. Box
CH-8021 Zurich
Switzerland
Phone: +41 1 268 1536
EMail: simon@switch.ch
Leinen Expires January 10, 2005 [Page 6]
Internet-Draft IPFIX over TCP July 2004
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Leinen Expires January 10, 2005 [Page 7]
| PAFTECH AB 2003-2026 | 2026-04-23 20:21:07 |