Network Working Group Kamran Raza Internet Draft Cisco Systems Intended Status: Standards Track Expiration Date: December 1, 2011 Sami Boutros Cisco Systems Carlos Pignataro Cisco Systems June 2, 2011 LDP Typed Wildcard FEC for the PW FEC Elements draft-raza-pwe3-pw-typed-wc-fec-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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Abstract The "Typed Wildcard Forwarding Equivalence Class (FEC) Element" defines an extension to the Label Distribution Protocol (LDP) that can be used when it is desired to request or withdraw or release all label bindings for a given FEC Element type. However, a typed wildcard FEC element must be individually defined for each FEC element type. This specification defines the typed wildcard FEC elements for the PWid (0x80), Generalized PWid (0x81), and P2MP PW (0x82) FEC element types. Conventions used in this document The keywords "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]. Table of Contents 1. Introduction 3 2. Typed Wildcard for PW FEC Elements 3 3. Applicability Statement 4 4. Operation 5 4.1. PW Consistency Check 5 4.2. PW Graceful Shutdown 5 4.3. Wildcard PW Status 6 5. Security Considerations 6 6. IANA Considerations 6 7. Acknowledgments 6 8. References 6 8.1. Normative References 6 8.2. Informative References 7 Author's Address 7 Raza, et al. Expires December 2011 [Page 2] Internet-Draft LDP Typed Wildcard PW FEC Elements June 2011 1. Introduction An extension [RFC5918] to the Label Distribution Protocol (LDP) [RFC5036] defines the general notion of a "Typed Wildcard Forwarding Equivalence Class (FEC) Element". This can be used when it is desired to request all label bindings for a given type of FEC Element, or to release or withdraw all label bindings for a given type of FEC element. However, a typed wildcard FEC element must be individually defined for each type of FEC element. [RFC4447] defines the "PWid FEC Element" and "Generalized PWid FEC Element", and [P2MP-PW] defines the "P2MP PW FEC Element". These specifications, however, do not specify the Typed Wildcard format for these elements. This document specifies the format of the Typed Wildcard FEC Element for the "PWid FEC Element", "Generalized PWid FEC Element", and "P2MP FEC Element". The procedures for Typed Wildcard processing for PWid, Generalized PWid, and P2MP FEC Elements are same as described in [RFC5918] for any typed wildcard FEC Element type. 2. Typed Wildcard for PW FEC Elements The format of the Typed Wildcard FEC Element for PWid, Generalized PWid, and P2MP PW FEC Elements is specified as: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Typed Wcard=0x5| Type=PW FEC | Len = 2 |R| PW type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . | +-+-+-+-+-+-+-+-+ Figure 1: Format of Typed Wildcard FEC Element for PW FEC Elements Where: Typed Wcard (one octet): Typed Wildcard FEC element type (0x05) as specified in [RFC5918] [FEC Element] Type (one octet): PW FEC Element type: PWid: (type 0x80 [RFC4447]) Generalized PWid: (type 0x81 [RFC4447]) P2MP PW: (type 0x82, [P2MP-PW] Raza, et al. Expires December 2011 [Page 3] Internet-Draft LDP Typed Wildcard PW FEC Elements June 2011 Len [FEC Type Info] (one octet): Two. (i.e. there is additional FEC info to scope the Typed Wildcard) Reserved bit: Must be set to ZERO on transmit and ignored on receipt. PW type (15-bits): PW type as specified in [RFC4447]. This field is used to scope the PWid wildcard FEC operation to limit to all PWs of a given type. This MUST be set to 0x7FFF (Wildcard PW [IANA-PWE3]) when referring PWs of all types (see Section 7). [RFC4447] defines "PW Grouping ID TLV" that can be used for wildcard withdrawal or status messages related to Generalized PWid and P2MP PW FECs. When Typed Wildcard FEC for Generalized PWid or P2MP PW FEC element is in use, "PW Grouping ID TLV" MUST NOT be present in the same message. If found present, receiving LSR MUST silently ignore Grouping ID TLV and process rest of the message. 3. Applicability Statement The Typed wildcard FEC Elements defined in this document for the PWid, Generalized PWid, and P2MP PW FEC Elements provide a finer degree of granularity when compared to the Wildcard FEC mechanics defined in [RFC5036]. The PWid FEC Element as defined in [RFC4447] contains a Group ID field. This field is defined as an arbitrary 32-bit value that represents a group of PWs, and is used to create groups in the PW space, including potentially a single group of all PWs for a given FEC Element. This grouping enables an LSR to send wildcard label withdrawals and/or status notification messages corresponding to a PW group upon physical port failures. Similarly, [RFC4447] defines the "PW Grouping ID TLV" used in the same fashion for the Generalized PWid and P2MP PW FEC Elements. The PW Typed Wildcard FEC elements defined in this document help us achieve the similar functionality as "Group ID" field or "PW Grouping ID TLV" for label withdrawal and status notification messages; Additionally, the Typed Wildcard procedures [RFC5918] also provide more generalized and comprehensive solution by allowing: 1. Typed-Wildcard Label Request message Raza, et al. Expires December 2011 [Page 4] Internet-Draft LDP Typed Wildcard PW FEC Elements June 2011 2. Label TLV to further constraint the wildcard to all FECs of the specified FEC type [and its specific filter] that are also bound to the specified label. 4. Operation The use of Typed Wildcard FEC elements for PW can be useful under several scenarios. This section describes two use cases to illustrate their usage. The following use cases consider two LSR nodes, A and B, with LDP session between them to exchange L2VPN PW bindings. 4.1. PW Consistency Check A user may request a control plane consistency check at LSR A for the PWid FEC and Generalized PWid FEC bindings that it had learnt from LSR B over LDP session. To perform this consistency check, LSR A marks all its learnt PW bindings from LSR B as stale, and then send a Label Request message towards LSR B with Typed Wildcard FEC element for PWid FEC element (PW type = 0x7FFF) and Generalized PWid FEC element (PW type = 0x7FFF). Upon receipt of such request, LSR B replays its database related to PWid FEC elements and Generalized PWid FEC element in Label Mapping message. As a PW binding is received at LSR A, the associated binding state is marked as refreshed (no stale). When replay completes for a given type of FEC, LSR B sends End-of-LIB Notification [RFC5919] to mark the end of update for the given FEC type. Upon receipt of this Notification at LSR A, any remaining stale PW binding of given FEC type learnt from the peer LSR B, is cleaned up and removed from the database. This completes consistency check with LSR B at LSR A for given FEC type. 4.2. PW Graceful Shutdown It may be desirable to perform shutdown/removal of existing PW bindings advertised towards a peer in a graceful manner -- i.e. all advertised PW bindings to be removed from a peer without session flap. For example, to request a graceful delete of the PWid FEC and Generalized PWid FEC bindings at LSR A learnt from LSR B, LSR A would send a Label Withdraw message towards LSR B with Typed Wildcard FEC elements pertaining to PWid FEC element (PW type = 0x7FFF) and Generalized PWid FEC element (PW type = 0x7FFF). Upon receipt of such message, LSR B will delete all PWid and Generalized PWid bindings learnt from LSR A. Afterwards, LSR B would send Label Release message corresponding to received Label Withdraw with Typed FEC element. Raza, et al. Expires December 2011 [Page 5] Internet-Draft LDP Typed Wildcard PW FEC Elements June 2011 4.3. Wildcard PW Status The Typed Wildcard FEC Elements for PW FECs can be very useful when used to convey PW status amongst LSRs. The PE devices can send "PW Status TLV" in an LDP Notification message to indicate status (i.e., a Pseudowire Status Code denoting for example a particular fault) to their remote peers [RFC4447]. In case of a global failure affecting all PWs, an LSR typically sends one PW Status Notification message per PW. Using Typed Wildcard FEC Element for given type of PW FEC Element, the LSR will need to send only one PW Status Notification message with Typed Wildcard PW FEC specified to notify about the common status applicable to all PWs as scoped by the PW Typed Wildcard FEC. 5. Security Considerations No new security considerations beyond that apply to the base LDP specification [RFC5036], [RFC4447] and [MPLS_SEC] apply to the use of the PW Typed Wildcard FEC Element types described in this document. 6. IANA Considerations None. 7. Acknowledgments The authors would like to thank Eric Rosen, Siva Sivabalan, and Zafar Ali for their valuable comments. This document was prepared using 2-Word-v2.0 template.dot. 8. References 8.1. Normative References [RFC5036] Andersson, L., Menei, I., and Thomas, B., Editors, "LDP Specification", RFC 5036, September 2007. [RFC5918] Asati, R., Minei, I., and Thomas, B., "LDP Typed Wildcard Forwarding Equivalence Class", RFC 5918, August 2010. [RFC5919] Asati, R., Mohapatra, P., Chen, E., and Thomas, B., "Signaling LDP Label Advertisement Completion", RFC 5919, Raza, et al. Expires December 2011 [Page 6] Internet-Draft LDP Typed Wildcard PW FEC Elements June 2011 August 2009. [RFC4447] L. Martini, Editor, E. Rosen, El-Aawar, T. Smith, G. Heron, "Pseudowire Setup and Maintenance using the Label Distribution Protocol", RFC 4447, April 2006. [P2MP-PW] Boutros, S., Martini, L., Sivabalan, S., Del Vecchio, G., Kamite, Jin, L., "Signaling Root-Initiated P2MP PWs using LDP", draft-ietf-pwe3-p2mp-pw-02.txt, Work in Progress, March 2011. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC2119, March 1997. 8.2. Informative References [MPLS_SEC] Fang, L. et al., "Security Framework for MPLS and GMPLS Networks", draft-ietf-mpls-mpls-and-gmpls-security-framework- 05.txt, Work in Progress, March 2009. [IANA-PWE3] Internet Assigned Numbers Authority, "Pseudo Wires Name Spaces (PWE3)", http://www.iana.org/assignments/pwe3- parameters, May 2011. Author's Address Kamran Raza Cisco Systems, Inc., 2000 Innovation Drive, Kanata, ON K2K-3E8, Canada. E-mail: skraza@cisco.com Sami Boutros Cisco Systems, Inc., 3750 Cisco Way, San Jose, CA 95134, USA. E-mail: sboutros@cisco.com Carlos Pignataro Cisco Systems, Inc., Raza, et al. Expires December 2011 [Page 7] Internet-Draft LDP Typed Wildcard PW FEC Elements June 2011 7200 Kit Creek Road, Research Triangle Park, NC 27709-4987, USA. Email: cpignata@cisco.com Raza, et al. Expires December 2011 [Page 8]