Internet DRAFT - draft-yong-pwe3-trill-o-pw
draft-yong-pwe3-trill-o-pw
TRILL Working Group Lucy Yong
INTERNET-DRAFT Donald Eastlake
Intended status: Proposed Standard Sam Aldrin
Huawei Technologies
Jon Hudson
Brocade
Expires: August 17, 2013 February 18, 2013
TRILL Over Pseudo Wires
<draft-yong-pwe3-trill-o-pw-00.txt>
Abstract
This document describes ways to interconnect a pair of TRILL
(Transparent Interconnection of Lots of Links) switch ports with two
types of pseudo wires 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 TRILL over PPP PWE3....................................4
2.3 TRILL over Ethernet PWE3...............................5
2.4 Preferable Pseudowire Type And Auto-Configuration......5
3. IANA Considerations.....................................6
4. Security Considerations.................................6
Acknowledgements...........................................7
Normative References.......................................7
Informative References.....................................7
Authors' Addresses.........................................9
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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).
End stations are attached to TRILL switches with Ethernet. But 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 form a TRILL campus which is bounded by end
stations and layer 3 routers. Such a campus may contain bridges.
This document specified the use of two types of PWE3 (Pseudowire
Emulation End-to-End) pseudowires as links between TRILL switches. It
is assumed that such pseudowires are implemented with MPLS.
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 Systme [IS-IS]
[RFC1195]
MPLS - Multi-Protocol Label Switching
PPP - Point-to-Point Protocol
PW - Pseudowire
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
PPP [RFC4618] or Ethernet [RFC4448] pseudowires may be used to
interconnect pairs of TRILL switch ports as described below. The
pseudowire between such ports can be auto-configured [RFC4447] or
manually configured. The TRILL switches, which are TRILL routers, are
also acting as label switched routers for those TRILL switch ports.
In both types, the pseudowire provides transparent transport and the
two RBridges appear directly interconnected with a transparent link.
With such an interconnection (and negotiation to use TRILL in the PPP
case [RFC6361]), the TRILL adjacency over that link is automatically
discovered and established through TRILL IS-IS control messages
[RFC6325] [RFC6327].
2.1 PWE3 Type Independent Details
The sending pseudowire TRILL switch port MUST copy the priority of
the TRILL packets being sent to the 3-bit Class of Service field of
the pseudowire label [RFC5462] so the priority will be visible to
transit devices that can take the priority into account.
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 device has no
awareness of TRILL. Such devices will not change the TRILL Header hop
count.
2.2 TRILL over PPP PWE3
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 negotatied within PPP, the two TRILL switches then
appear directly connected with a PPP link [RFC1661].
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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2.3 TRILL over Ethernet PWE3
For an Ethernet pseudowire, the two TRILL switch ports being
connected are configured to form a pseudowire with Ethernet
encapsulation [RFC4448]. The ports MUST use the Raw mode (PW type =
0x0005) and non-service-delimiting, to provide as transparent an
Ethernet transport as practical. The two RBridges then appear
directly interconnected with an Ethernet link [RFC6325].
Behavior for TRILL with an Ethernet psuedo wire continue to follow
that over Ethernet as specified in [RFC6325] and [RFC6327].
2.4 Preferable Pseudowire Type And Auto-Configuration
Use of the PPP pseduowire type is preferable to the Ethernet
pseudowire type for the connections discussed in this document. It
saves 12 or 16 bytes on every TRILL packet. In particular, the Link
Header in the PPP case is simply a 2-byte PPP code point while for
the Ethernet case it is 14 or 18 bytes (Outer.MacDA (6), Outer.MacSA
(6), sometimes Outer.VLAN (4), and TRILL Ethertype (2)). (While it
would also be possible to specify a special custom pseudowire type
for TRILL traffic, the authors feel that any efficiency gain over PPP
pseudowires would be too small to be worth the complexity of adding
such a specification.)
If pseudowire interconnection of two TRILL switch ports is auto-
configured [RFC4447] and the initiating RBridge port supports PPP
pseudowires, it SHOULD initially attempt the connection set-up with
PW type PPP (0x0007). If that pseudowire type is rejected, it SHOULD
try again with the Ethernet PW type recommended above (0x0005) if it
supports that type. If a responding RBridge port receives a set-up
attempt specifying PPP, it SHOULD accept the connection if it
supports PPP. If a responding RBridge port receives a set-up attempt
specifying Ethernet (PW type = 0x0005), it SHOULD assume that the
initiator does not aupport PPP and accept or reject the Ethernet set-
up attempt depending on whether or not it supports Ethernet. SHOULD
is specified because local policy as to what pseudowires connections
and types are allowed may override these guidelines.
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3. IANA Considerations
No IANA action is required by this document. RFC Editor: Please
remove this section before publication.
4. Security Considerations
For general TRILL protocol security considerations and those related
to Ethernet links, see [RFC6325].
For PPP link TRILL security consideraitons, see [RFC6361].
For security considerations introduced by carrying Ethernet or 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.
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Acknowledgements
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.
[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.
[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 Edtior's queue.
Informative References
[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
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providing the connectionless-mode Network Service (ISO 8473)",
ISO/IEC10589:2002, Second Edition, Nov 2002
[RFC1195] - Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC3985] - Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC6327] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Dutt, D.,
and V. Manral, "Routing Bridges (RBridges): Adjacency", RFC
6327, July 2011.
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Authors' Addresses
Lucy Yong
Huawei R&D USA
5340 Legacy Drive
Plano, TX 75025 USA
Phone: +1-469-227-5837
Email: lucy.yong@huawei.com
Donald E. Eastlake, 3rd
Huawei R&D USA
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Sam Aldrin
Huawei R&D USA
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@brocade.com
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