TRILL Working Group Lucy Yong
INTERNET-DRAFT Donald Eastlake
Intended status: Proposed Standard Sam Aldrin
Huawei Technologies
Jon Hudson
Brocade
Expires: April 19, 2014 October 20, 2013
Transport of TRILL Using Pseudowires
<draft-ietf-trill-o-pw-01.txt>
Abstract
This document specifies how to interconnect a pair of TRILL
(Transparent Interconnection of Lots of Links) switch ports using
pseudowires under existing TRILL and PWE3 (Pseudowire Emulation End-
to-End) standards.
Status of This Memo
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Table of Contents
1. Introduction............................................3
1.1 Conventions used in this document......................3
2. PWE3 Interconnection of TRILL Switches..................4
2.1 PWE3 Type Independent Details..........................4
2.2 PPP PWE3 Transport of TRILL............................5
3. IANA Considerations.....................................6
4. Security Considerations.................................6
Appendix A: Use of Other Pseudowire Types..................7
Appendix Z: Change History.................................8
Acknowledgements...........................................9
Normative References.......................................9
Informative References.....................................9
Authors' Addresses........................................11
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1. Introduction
The IETF has standardized the TRILL (Transparent Interconnection of
Lots of Links) protocol [RFC6325] that provides optimal pair-wise
data frame routing without configuration in multi-hop networks with
arbitrary topology. TRILL supports multipathing of both unicast and
multicast traffic. Devices that implement TRILL are called TRILL
Switches or RBridges (Routing Bridges).
Links between TRILL Switches can be based on arbitrary link
protocols, for example PPP [RFC6361], as well as Ethernet [RFC6325].
A set of connected TRILL Switches together form a TRILL campus which
is bounded by end stations and layer 3 routers.
This document specifies how to interconnect a pair of TRILL Switch
ports using a pseudowire under existing TRILL and PWE3 (Pseudowire
Emulation End-to-End) standards.
1.1 Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Acronyms used in this document include the following:
IS-IS - Intermediate System to Intermediate System [IS-IS]
MPLS - Multi-Protocol Label Switching
PPP - Point-to-Point Protocol [RFC1661]
PW - Pseudowire [RFC3985]
PWE3 - PW Emulation End-to-End
RBridge - Routing Bridge, an alternative name for a TRILL Switch
TRILL - Transparent Interconnection of Lots of Links [RFC6325]
TRILL Switch - A device implementing the TRILL protocol
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2. PWE3 Interconnection of TRILL Switches
When a pseudowire is used to interconnect a pair of TRILL Switch
ports, a PPP [RFC4618] pseudowire is used as described below. The
pseudowire between such ports can be auto-configured [RFC4447] or
manually configured. In this context, the TRILL Switch ports at the
ends of the pseudowire are acting as native service processing
elements (NSP [RFC3985]) and, assuming the pseudowires are over MPLS
or IP [RFC4023] networks, as label switched or IP routers at the
TRILL Switch ports.
Pseudowires provide transparent transport and the two TRILL Switch
ports appear directly interconnected with a transparent link. With
such an interconnection the TRILL adjacency over the link is
automatically discovered and established through TRILL IS-IS control
messages [RFC6327bis].
A pseudowire is carried over a packet switched network tunnel
[RFC3985]. For example, an MPLS or MPLS-TP label switched path
tunnel in MPLS networks. Either a signaling protocol or manual
configuration can be used to configure a label switched path tunnel
between two TRILL Switch ports. This application needs no additions
to the existing pseudowire standards.
2.1 PWE3 Type Independent Details
The sending pseudowire TRILL Switch port MUST copy the priority of
the TRILL Data packets being sent to the 3-bit Traffic Class field of
the pseudowire label [RFC5462] so the priority will be visible to
pseudowire transit devices and they can take the priority into
account. TRILL IS-IS PDUs critical to establishing and maintaining
adjacency (Hello and MTU PDUs) SHOULD be send with Traffic Class 7
while other TRILL IS-IS PDUs SHOULD be sent with Traffic Class 6.
If a pseudowire supports fragmentation and re-assembly, there is no
reason to do TRILL MTU testing on it and the pseudowire will not be a
constraint on the TRILL campus wide Sz (see Section 4.3.1 [RFC6325]).
If the pseudowire does not support fragmentation, then the available
TRILL IS-IS packet payload size over the pseudowire (taking into
account MPLS encapsulation with a control word) or some lower value,
MUST be used in helping to determine Sz (see Section 5
[ClearCorrect]).
An intervening MPLS label switched router or similar packet switched
network device has no awareness of TRILL. Such devices will not
change the TRILL Header hop count.
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2.2 PPP PWE3 Transport of TRILL
For a PPP pseudowire (PW type = 0x0007), the two TRILL Switch ports
being connected are configured to form a pseudowire with PPP
encapsulation [RFC4618]. After the pseudowire is established and
TRILL use is negotiated within PPP, the two TRILL Switch ports appear
directly connected with a PPP link [RFC1661] [RFC6361].
If pseudowire interconnection of two TRILL Switch ports is auto-
configured [RFC4447], the initiating TRILL Switch port MUST attempt
the connection set-up with pseudowire type PPP (0x0007).
Behavior for TRILL with a PPP pseudowire continues to follow that of
TRILL over PPP as specified in Section 3 of [RFC6361].
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3. IANA Considerations
No IANA actions are required by this document. RFC Editor: Please
remove this section before publication.
4. Security Considerations
For PPP link TRILL security considerations, see [RFC6361].
For security considerations introduced by carrying PPP TRILL links
over pseudowires, see [RFC3985].
Not all implementations need to include specific security mechanisms
at the pseudowire layer, for example if they are designed to be
deployed only in cases where the networking environment is trusted or
where other layers provide adequate security. A complete enumeration
of possible deployment scenarios and associated threats and options
is not possible and is outside the scope of this document. For
applications involving sensitive data, end-to-end security should
always be considered, in addition to link security, to provide
security in depth. In this context, such end-to-end security should
be between the end stations involved so as to protect the entire path
to, through, and from the TRILL campus.
For general TRILL protocol security considerations, see [RFC6325].
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Appendix A: Use of Other Pseudowire Types
This informational Appendix briefly discusses use of pseudowire types
other than PPP.
The use of Ethernet pseudowires [RFC4448] was examined by the authors
and would be possible; however, they would require an additional 12
or 16 bytes per packet.
It would also be possible to specify a new pseudowire type for TRILL
traffic but the authors feel that any efficiency gain over PPP
pseudowires would be too small to be worth the complexity of adding
such a specification. Furthermore using PPP pseudowire encoding means
that any traffic dissector that understands TRILL PPP encoding
[RFC6361] and understands PPP pseudowires [RFC4618] will
automatically be able to recursively decode TRILL transported by
pseudowire.
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Appendix Z: Change History
From -00 to -01
Add information on Traffic Classes that should be used for TRILL IS-
IS PDUs.
Other changes to resolve WG Last Call comments:
Change title from "TRILL Over Psuedowires".
Change "Class of Service" to "Traffic Class".
Expand informational paragraph about the consideration of using
other pseudowire types for the transport of TRILL and make that
paragraph into Appendix A.
Add this Change History Appendix Z.
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Acknowledgements
Thanks for the valuable comments from the following:
Yakov Stein
The document was prepared in raw nroff. All macros used were defined
within the source file.
Normative References
[RFC1661] - Simpson, W., Ed., "The Point-to-Point Protocol (PPP)",
STD 51, RFC 1661, July 1994.
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4447] - Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and
G. Heron, "Pseudowire Setup and Maintenance Using the Label
Distribution Protocol (LDP)", RFC 4447, April 2006.
[RFC4618] - Martini, L., "Encapsulation Methods for Transport of
PPP/High-Level Data Link Control (HDLC) over MPLS Networks",
BCP 116, RFC 4618, September 2006.
[RFC5462] - Andersson, L. and R. Asati, "Multiprotocol Label
Switching (MPLS) Label Stack Entry: "EXP" Field Renamed to
"Traffic Class" Field", RFC 5462, February 2009.
[RFC6325] - Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC6325, July 2011.
[RFC6361] - Carlson, J., and D. Eastlake, "PPP Transparent
Interconnection of Lots of Links (TRILL) Protocol Control
Protocol", RFC6361, August 2011.
[ClearCorrect] - Eastlake, D., M. Zhang, A. Ghanwani, V. Manral, and
A. Banerjee, "TRILL: Clarifications, Corrections, and Updates",
draft-ietf-trill-clear-correct, in RFC Editor's queue.
Informative References
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[IS-IS] - International Organization for Standardization,
"Intermediate system to Intermediate system intra-domain
routing information exchange protocol for use in conjunction
with the protocol for providing the connectionless-mode Network
Service (ISO 8473)", ISO/IEC10589:2002, Second Edition, Nov
2002
[RFC3985] - Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC4023] - Worster, T., Rekhter, Y., and E. Rosen, Ed.,
"Encapsulating MPLS in IP or Generic Routing Encapsulation
(GRE)", RFC 4023, March 2005.
[RFC4448] - Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
"Encapsulation Methods for Transport of Ethernet over MPLS
Networks", RFC 4448, April 2006.
[RFC6327bis] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Howard,
Y., and V. Manral, "TRILL: Adjacency", draft-ietf-trill-
rfc6327bis, work in progress.
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Authors' Addresses
Lucy Yong
Huawei Technologies
5340 Legacy Drive
Plano, TX 75025 USA
Phone: +1-469-227-5837
Email: lucy.yong@huawei.com
Donald E. Eastlake, 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Sam Aldrin
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050 USA
Phone: +1-408-330-4517
Email: sam.aldrin@huawei.com
Jon Hudson
Brocade
130 Holger Way
San Jose, CA 95134 USA
Phone: +1-408-333-4062
jon.hudson@gmail.com
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