Internet Engineering Task Force (IETF) K. Raza Request for Comments: 7358 S. Boutros Updates: 3212, 4447, 5036, 5918, 6388, 7140 L. Martini Category: Standards Track Cisco Systems, Inc. ISSN: 2070-1721 N. Leymann Deutsche Telekom October 2014
Label Advertisement Discipline for LDP Forwarding Equivalence Classes (FECs)
Abstract
The label advertising behavior of an LDP speaker for a given Forwarding Equivalence Class (FEC) is governed by the FEC type and not necessarily by the LDP session's negotiated label advertisement mode. This document updates RFC 5036 to make that fact clear. It also updates RFCs 3212, 4447, 5918, 6388, and 7140 by specifying the label advertisement mode for all currently defined LDP FEC types.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7358.
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RFC 7358 Label Advert. Discipline for LDP FECs October 2014
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The Label Distribution Protocol (LDP) [RFC5036] allows label advertisement mode negotiation at the time of session establishment. The LDP specification also dictates that only a single label advertisement mode be negotiated, agreed upon, and used for a given LDP session between two Label Switching Routers (LSRs).
The negotiated label advertisement mode defined in RFC 5036 and carried in the LDP Initialization message is only indicative. It indicates how the LDP speakers on a session will advertise labels for some Forwarding Equivalence Classes (FECs), but it is not a rule that restricts the speakers to behave in a specific way. Furthermore, for some FEC types the advertising behavior of the LDP speaker is governed by the FEC type and not by the negotiated behavior.
This document updates [RFC5036] to make that fact clear. It also updates [RFC3212], [RFC4447], [RFC5918], [RFC6388], and [RFC7140] to indicate, for each FEC type that has already been defined, whether
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the label binding advertisements for the FEC are constrained by the negotiated label advertisement mode or not. Furthermore, this document specifies the label advertisement mode to be used for all currently defined FECs.
To remove any ambiguity and conflict regarding a label advertisement discipline among different FEC types sharing a common LDP session, this document specifies a label advertisement discipline for FEC types.
This document introduces the following types for specifying a label advertisement discipline for a FEC type:
- DU (Downstream Unsolicited) - DoD (Downstream on Demand) - As negotiated (DU or DoD) - Upstream ([RFC6389]) - Not applicable - Unknown
Section 3.5.3 of [RFC5036] is updated to add the following two statements under the description of "A, Label Advertisement Discipline":
- Each document defining an LDP FEC must state the applicability of the negotiated label advertisement discipline for label binding advertisements for that FEC. If the negotiated label advertisement discipline does not apply to the FEC, the document must also explicitly state the discipline to be used for the FEC.
- This document defines the label advertisement discipline for the following FEC types:
+----------+----------+--------------------------------+ | FEC Type | FEC Name | Label Advertisement Discipline | +----------+----------+--------------------------------+ | 0x01 | Wildcard | Not applicable | | 0x02 | Prefix | As negotiated (DU or DoD) | +----------+----------+--------------------------------+
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This document only clarifies the applicability of an LDP session's label advertisement mode and hence does not add any LDP security mechanics and considerations to those already defined in the LDP specification [RFC5036].
This document mandates the specification of a label advertisement discipline for each defined FEC type and hence IANA's "Forwarding Equivalence Class (FEC) Type Name Space" registry under IANA's "Label Distribution Protocol (LDP) Parameters" registry has been extended as follows:
- Added a new column titled "Label Advertisement Discipline" with the following possible values:
o DU o DoD o As negotiated (DU or DoD) o Upstream o Not applicable o Unknown
- Made this document an additional reference for the registry itself and for all affected registrations.
- Kept other columns of the registry in place and populated as they were.
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For the currently assigned FEC types, the updated registry looks like:
[RFC3212] Jamoussi, B., Ed., Andersson, L., Callon, R., Dantu, R., Wu, L., Doolan, P., Worster, T., Feldman, N., Fredette, A., Girish, M., Gray, E., Heinanen, J., Kilty, T., and A. Malis, "Constraint-Based LSP Setup using LDP", RFC 3212, January 2002, <http://www.rfc-editor.org/info/rfc3212>.
[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, <http://www.rfc-editor.org/info/rfc4447>.
[RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B. Thomas, "Label Distribution Protocol Extensions for Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths", RFC 6388, November 2011, <http://www.rfc-editor.org/info/rfc6388>.
[FAST-PROT] Shen, Y., Aggarwal, R., Henderickx, W., and Y. Jiang, "PW Endpoint Fast Failure Protection", Work in Progress, draft-ietf-pwe3-endpoint-fast-protection-01, July 2014.
[P2MP-PW] Sivabalan, S., Ed., Boutros, S., Ed., Martini, L., Konstantynowicz, M., Del Vecchio, G., Nadeau, T., Jounay, F., Niger, P., Kamite, Y., Jin, L., Vigoureux, M., Ciavaglia, L., Delord, S., and K. Raza, "Signaling Root-Initiated Point-to-Multipoint Pseudowire using LDP", Work in Progress, draft-ietf-pwe3-p2mp-pw-04, March 2012.
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RFC 7358 Label Advert. Discipline for LDP FECs October 2014
Acknowledgments
We acknowledge Eric Rosen and Rajiv Asati for their initial review and input on the document.
Authors' Addresses
Kamran Raza Cisco Systems, Inc. 2000 Innovation Drive Ottawa, ON K2K-3E8 Canada
EMail: skraza@cisco.com
Sami Boutros Cisco Systems, Inc. 3750 Cisco Way San Jose, CA 95134 United States
EMail: sboutros@cisco.com
Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO 80112 United States
EMail: lmartini@cisco.com
Nicolai Leymann Deutsche Telekom AG Winterfeldtstrasse 21 Berlin 10781 Germany