These three motivations need to satisfy the following:
- In (1) and (2), collection of information on a per-LSP
basis is a minimum level of granularity for collecting
accounting information at both of ingress and egress of an
LSP.
- In (3), SP’s ASBR carry out interconnection functions as an
intermediate LSR. Therefore, identifying a pair of ingress
and egress LSRs using each LSP is needed to determine the
cost of the service that a customer is using.
4.11.1. Requirements
Accounting on a per-LSP basis encompasses the following set of
functions:
(1) At an ingress LSR, accounting of traffic through LSPs that
begin at each egress in question.
(2) At an intermediate LSR, accounting of traffic through LSPs for
each pair of ingress to egress.
(3) At egress LSR, accounting of traffic through LSPs for each
ingress.
(4) All LSRs containing LSPs that are being measured need to have
a common identifier to distinguish each LSP. The identifier
MUST be unique to each LSP, and its mapping to LSP SHOULD be
provided whether from manual or automatic configuration.
In the case of non-merged LSPs, this can be achieved by simply
reading traffic counters for the label stack associated with the
LSP at any LSR along its path. However, in order to measure
merged LSPs, an LSR MUST have a means to distinguish the source of
each flow so as to disambiguate the statistics.
4.11.2. Location of Accounting
It is not realistic for LSRs to perform the described operations on
all LSPs that exist in a network. At a minimum, per-LSP based
accounting SHOULD be performed on the edges of the network -- at the
edges of both LSPs and the MPLS domain.
5. Security Considerations
Provisions to any of the network mechanisms designed to satisfy the
requirements described herein are required to prevent their
unauthorized use. Likewise, these network mechanisms MUST provide a
means by which an operator can prevent denial of service attacks if
those network mechanisms are used in such an attack.
LSP mis-merging has security implications beyond that of simply being
a network defect. LSP mis-merging can happen due to a number of
potential sources of failure, some of which (due to MPLS label
stacking) are new to MPLS.
The performance of diagnostic functions and path characterization
involve extracting a significant amount of information about network
construction that the network operator MAY consider private.
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2. Informative References
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006.
[RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Traffic Engineering
(TE) Management Information Base (MIB)", RFC 3812, June
2004.
[RFC3813] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Label Switching
Router (LSR) Management Information Base (MIB)", RFC 3813,
June 2004.
[RFC3814] Nadeau, T., Srinivasan, C., and A. Viswanathan,
"Multiprotocol Label Switching (MPLS) Forwarding
Equivalence Class To Next Hop Label Forwarding Entry
(FEC-To-NHLFE) Management Information Base (MIB)", RFC
3814, June 2004.
[Y1710] ITU-T Recommendation Y.1710, "Requirements for OAM
Functionality In MPLS Networks"
[I610] ITU-T Recommendation I.610, "B-ISDN operations and
maintenance principles and functions", February 1999
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC792] Postel, J., "Internet Control Message Protocol", STD 5, RFC
792, September 1981.
[RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing in
Multi-Protocol Label Switching (MPLS) Networks", RFC 3443,
January 2003.
7. Acknowledgements
The authors wish to acknowledge and thank the following individuals
for their valuable comments to this document: Adrian Smith, British
Telecom; Chou Lan Pok, SBC; Mr. Ikejiri, NTT Communications; and Mr.
Kumaki, KDDI. Hari Rakotoranto, Miya Kohno, Cisco Systems; Luyuan
Fang, AT&T; Danny McPherson, TCB; Dr. Ken Nagami, Ikuo Nakagawa,
Intec Netcore, and David Meyer.
Authors’ Addresses
Comments should be made directly to the MPLS mailing list
at mpls@lists.ietf.org.
Thomas D. Nadeau
Cisco Systems, Inc.
300 Beaver Brook Road
Boxboro, MA 01719
Phone: +1-978-936-1470
EMail: tnadeau@cisco.com
Monique Jeanne Morrow
Cisco Systems, Inc.
Glatt-Com, 2nd Floor
CH-8301
Switzerland
Phone: (0)1 878-9412
EMail: mmorrow@cisco.com
George Swallow
Cisco Systems, Inc.
300 Beaver Brook Road
Boxboro, MA 01719
Phone: +1-978-936-1398
EMail: swallow@cisco.com
David Allan
Nortel Networks
3500 Carling Ave.
Ottawa, Ontario, CANADA
Phone: 1-613-763-6362
EMail: dallan@nortel.com
Satoru Matsushima
Japan Telecom
1-9-1, Higashi-Shinbashi, Minato-ku
Tokyo, 105-7316 Japan
Phone: +81-3-6889-1092
EMail: satoru@ft.solteria.net
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