PPP Transparent Interconnection of Lots of Links (TRILL) Protocol Control Protocol
draft-ietf-pppext-trill-protocol-08
The information below is for an old version of the document that is already published as an RFC.
| Document | Type | RFC Internet-Draft (trill WG) | |
|---|---|---|---|
| Author | James D. Carlson | ||
| Last updated | 2015-10-14 (Latest revision 2011-06-14) | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text htmlized pdfized bibtex | ||
| Reviews | |||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | RFC 6361 (Proposed Standard) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | Jari Arkko | ||
| IESG note | James Carlson (carlsonj@workingcode.com) is the document shepherd. | ||
| Send notices to | pppext-chairs@ietf.org |
draft-ietf-pppext-trill-protocol-08
Network Working Group James Carlson
INTERNET-DRAFT WorkingCode
Intended status: Proposed Standard Donald Eastlake
Huawei
Expires: December 12, 2011 June 13, 2011
PPP TRILL Protocol Control Protocol
<draft-ietf-pppext-trill-protocol-08.txt>
Abstract
The Point-to-Point Protocol (PPP) defines a Link Control Protocol
(LCP) and a method for negotiating the use of multi-protocol traffic
over point-to-point links. This document describes PPP support for
the Transparent Interconnection of Lots of Links (TRILL) Protocol,
allowing direct communication between Routing Bridges (RBridges) via
PPP links.
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Distribution of this document is unlimited. Comments should be sent
to the DNSEXT working group mailing list: <rbridge@postel.org>.
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J. Carlson & D. Eastlake [Page 1]
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Table of Contents
1. Introduction............................................3
2. PPP TRILL Negotiation...................................4
2.1 TNCP Packet Format.....................................4
2.2 TNP Packet Format......................................5
2.3 TLSP Packet Format.....................................6
3. TRILL PPP Behavior......................................7
4. Security Considerations.................................8
5. IANA Considerations.....................................8
6. References..............................................9
6.1 Normative..............................................9
6.2 Informative............................................9
7. Acknowledgments........................................10
8. Authors' Addresses.....................................10
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1. Introduction
The TRILL Protocol [RFCtrill] defines a set of mechanisms used to
communicate between RBridges. These devices can bridge together
large 802 networks using link-state protocols in place of the
traditional spanning tree mechanisms.
Over Ethernet, TRILL uses two separate Ethertypes to distinguish
between encapsulation headers, which carry user data, and link-state
messages, which compute network topology using a protocol based on
[IS-IS]. These two protocols must be distinguished from one another,
and segregated from all other traffic.
In a network where PPP [RFC1661] is used to interconnect routers
(often over telecommunications links), it may be advantageous to be
able to bridge between Ethernet segments over those PPP links, and
thus integrate remote networks with an existing TRILL cloud. The
existing Bridging Control Protocol (BCP) [RFC3518] allows direct
bridging of Ethernet frames over PPP. However, this mechanism is
inefficient and inadequate for TRILL, which can be optimized for use
over PPP links.
To interconnect these devices over PPP links, three protocol numbers
are needed, and are reserved as follows:
Value (in hex) Protocol Name
-------------- -------------------------------------
TBD-00XX TRILL Network Protocol (TNP)
TBD-40YY TRILL Link State Protocol (TLSP)
TBD-80ZZ TRILL Network Control Protocol (TNCP)
The usage of these three protocols is described in detail in the
following section.
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].
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2. PPP TRILL Negotiation
The TRILL Network Control Protocol (TNCP) is responsible for
negotiating the use of the TRILL Network Protocol (TNP) and TRILL
Link State Protocol (TLSP) on a PPP link. TNCP uses the same option
negotiation mechanism and state machine as described for LCP (section
4 of [RFC1661]).
TNCP packets MUST NOT be exchanged until PPP has reached the Network-
Layer Protocol phase. Any TNCP packets received when not in that
phase MUST be silently ignored.
The encapsulated network layer data, carried in TNP packets, and
topology information, carried in TLSP packets, MUST NOT be sent
unless TNCP is in Opened state. If a TNP or TLSP packet is received
when TNCP is not in Opened state and LCP is Opened, an implementation
MUST silently discard the unexpected TNP or TLSP packet.
2.1 TNCP Packet Format
Exactly one TNCP packet is carried in the PPP Information field, with
the PPP Protocol field set to hex TBD-80ZZ (TNCP). A summary of the
TNCP packet format is shown below. The fields are transmitted from
left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+
Code
Only LCP Code values 1 through 7 (Configure-Request, Configure-
Ack, Configure-Nak, Configure-Reject, Terminate-Request,
Terminate-Ack, and Code-Reject) are used. All other codes SHOULD
result in a TNCP Code-Reject reply.
Identifier and Length
These are as documented for LCP.
Data
This field contains data formatted as described in section 5 of
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[RFC1661]. Codes 1-4 use Type-Length-Data sequences, Codes 5 and
6 use uninterpreted data, and Code 7 uses a Rejected-Packet, all
as described in [RFC1661].
Because no Configuration Options have been defined for TNCP,
negotiating the use of TRILL Protocol with IS-IS for the link state
protocol is the default when no options are specified. A future
document may specify the use of Configuration Options to enable
different TRILL operating modes, such as the use of a different link
state protocol.
2.2 TNP Packet Format
When TNCP is in Opened state, TNP packets are sent by setting the PPP
Protocol field to hex TBD-00XX (TNP) and placing TRILL-encapsulated
data representing exactly one encapsulated packet in the PPP
Information field.
A summary of this format is provided below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| V | R |M|Op-Length| Hop Count | Egress (RB2) Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress (RB1) Nickname | Inner Destination MAC ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
This is identical to the TRILL Ethernet format (section 4.1 of
[RFCtrill], "Ethernet Data Encapsulation,") except that the Outer MAC
header and Ethertype are replaced by the PPP headers and Protocol
Field, and the Ethernet FCS is not present. Both user data and ESADI
packets are encoded in this format.
The PPP FCS follows the encapsulated data on links where the PPP FCS
is in use.
Unlike the TRILL Ethernet encapsulation, PPP nodes do not have MAC
addresses, so no outer MAC is present. (HDLC addresses MAY be
present in some situations; such usage is outside the scope of this
document.)
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2.3 TLSP Packet Format
When TNCP is in Opened state, TLSP packets are sent by setting the
PPP Protocol field to hex TBD-40YY (TLSP) and placing exactly one IS-
IS Payload (section 4.2.3 of [RFCtrill], "TRILL IS-IS Frames") in the
PPP Information field.
Note that point-to-point IS-IS links have only an arbitrary Circuit
ID, and do not use MAC addresses for identification.
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3. TRILL PPP Behavior
1. On a PPP link, TRILL always uses P2P Hellos. There is no need for
TRILL-Hello frames, nor is per-port configuration necessary. P2P
Hello messages, per "Point-to-Point IS to IS Hello PDU" (section
9.7 of [IS-IS]), do not use Neighbor IDs in the same manner as on
Ethernet. However, per section 4.2.4.1 of [RFCtrill], three-way
IS-IS handshake using extended circuit IDs is required on point-
to-point links, such as PPP.
2. RBridges are never appointed forwarders on PPP links. If an
implementation includes BCP [RFC3518], then it MUST ensure that
only one of BCP or TNCP is negotiated on a link, and not both. If
the peer is an RBridge, then there is no need to pass
unencapsulated frames, as the link can have no TRILL-ignorant peer
to be concerned about. If the peer is not an RBridge, then TNCP
negotiation fails and TRILL is not used on the link.
3. An implementation that has only PPP links might have no
Organizationally Unique Identifier (OUI) that can form an IS-IS
System ID. Resolving that issue is outside the scope of this
document, however it is strongly RECOMMENDED that all TRILL
implementations have at least one zero-configuration mechanism to
obtain a valid System ID. Refer to ISO/IEC 10589 regarding System
ID uniqueness requirements.
4. TRILL MTU-probe and TRILL MTU-ack messages (section 4.3.2 of
[RFCtrill]) are not needed on a PPP link. Implementations MUST
NOT send MTU-probe and SHOULD NOT reply to these messages. The
MTU computed by LCP SHOULD be used instead. Negotiating an LCP
MTU of at least 1524, to allow for an inner Ethernet payload of
1500 octets, is RECOMMENDED.
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4. Security Considerations
Existing PPP and IS-IS security mechanisms may play important roles
in a network of RBridges interconnected by PPP links. The IS-IS
authentication mechanism [RFC5304] [RFC5310], at the TRILL IS-IS
layer, prevents fabrication of link-state control messages.
Not all implementations need to include specific security mechanisms
at the PPP 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.
However, in case a PPP layer authentication mechanism to protect the
establishment of a link and identify a link with a known peer is
needed, implementation of PPP CHAP [RFC1994] is RECOMENDED. Should
greater flexibility be required than that provided by CHAP, EAP
[RFC3748] is a good alternative.
If TRILL over PPP packets also require confidentiality, the PPP ECP
link encryption mechanisms [RFC1968] can protect the confidentiality
and integrity of all packets on the PPP link.
And when PPP is run over tunneling mechanisms, such as L2TP
[RFC3931], tunnel security protocols may be available.
For general TRILL protocol security considerations, see [RFCtrill].
5. IANA Considerations
IANA is requested to assigned three PPP Protocol field values,
TBD-00XX, TBD-40YY, and TBD-80ZZ, as described in Section 1 of this
document.
IANA is requested to create a new "PPP TNCP Configuration Option
Types" in the PPP-Numbers registry using the same format as the
existing "PPP LCP Configuration Option Types" table.
All TNCP Configuration Option Types except 00 are "Unassigned" and
available for future use, based on "IETF Review," as described in BCP
26 [RFC5226]. Option 00 is allocated for use with Vendor Specific
Options, as described in [RFC2153].
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6. References
Normative and Informational references are listed below.
6.1 Normative
[RFC1661] - W. Simpson, Editor, "The Point-to-Point Protocol (PPP),"
RFC 1661, July 1994
[RFC2119] - S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels," BCP 14 and RFC 2119, March 1997
[RFC5226] - T. Narten and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs," BCP 26 and RFC 5226, May
2008
[RFCtrill] - R. Perlman, et al., "RBridges: Base Protocol
Specification," draft-ietf-trill-rbridge-protocol-16.txt, in
RFC Editor queue
6.2 Informative
[IS-IS] - International Organization for Standardization,
"Intermediate system to Intermediate system intra-domain
routeing information exchange protocol for use in conjunction
with the protocol for providing the connectionless-mode Network
Service (ISO 8473)", ISO/IEC 10589:2002, Second Edition, Nov
2002
[RFC1968] - G. Meyer, "The PPP Encryption Control Protocol (ECP),"
RFC 1968, June 1996
[RFC1994] - W. Simpson, "PPP Challenge Handshake Authentication
Protocol (CHAP)," RFC 1994, August 1996
[RFC2153] - W. Simpson, "PPP Vendor Extensions," RFC 2153, May 1997
[RFC3518] - M. Higashiyama, et al., "Point-to-Point Protocol (PPP)
Bridging Control Protocol (BCP)," RFC 3518, April 2003
[RFC3748] - B. Aboba, et al., "Extensible Authentication Protocol
(EAP)," RFC 3748, June 2004
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[RFC3931] - J. Lau, Ed., et al., "Layer Two Tunneling Protocol -
Version 3 (L2TPv3)," RFC 3931, March 2005
[RFC5304] - T. Li and R. Atkinson, "IS-IS Cryptographic
Authentication," RFC 5304, October 2008
[RFC5310] - Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC
5310, February 2009.
7. Acknowledgments
The authors thanks Jari Arkko, Stewart Bryant, Ralph Droms, Linda
Dunbar, Adrian Farrel, Stephen Farrell, Radia Perlman, Mike Shand,
and William A. Simpson for their comments and help.
8. Authors' Addresses
James Carlson
WorkingCode
25 Essex Street
North Andover, MA 01845 USA
Phone: +1-781-301-2471
Email: carlsonj@workingcode.com
Donald Eastlake, 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
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J. Carlson & D. Eastlake [Page 11]