MPLS Working Group G. Mirsky Internet-Draft Ericsson Intended status: Standards Track J. Drake Expires: April 24, 2014 K. Holleman Juniper Networks S. Bryant Cisco Systems A. Vainshtein ECI Telecom October 21, 2013 Residence Time Measurment in MPLS network draft-mirsky-mpls-residence-time-00 Abstract This document specifies G-ACh based Residence Time Measurement and how it can be used by time synchronization protocols being transported over MPLS domain. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 24, 2014. Copyright Notice Copyright (c) 2013 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 Mirsky, et al. Expires April 24, 2014 [Page 1] Internet-Draft Residence Time Measurement October 2013 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . . 3 1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . 3 1.1.2. Requirements Language . . . . . . . . . . . . . . . . . 3 2. Residence Time Measurement . . . . . . . . . . . . . . . . . . 4 3. G-ACh for Residence Time Measurement . . . . . . . . . . . . . 4 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Mirsky, et al. Expires April 24, 2014 [Page 2] Internet-Draft Residence Time Measurement October 2013 1. Introduction Time synchronization protocols, Network Time Protocol version 4 (NTPv4) [RFC5905] and Precision Time Protocol (PTP) Version 2, a.k.a. IEEE-1588 v.2, can be used to syncronized clocks across network domain. In some scenarios calculation of time packet of time syncronization protocol spends within a node, called Resident Time, can improve accuracy of clock syncronization. This document defines new Generalized Associated Channel (G-ACh) that can be used in Multi- Protocol Label Switching (MPLS) network to measure Residence Time over Label Switched Path (LSP) or Pseudo-wire (PW). Transport of packets of a time synchronization protocol over MPLS domain is outside of scope of this document. 1.1. Conventions used in this document 1.1.1. Terminology MPLS: Multi-Protocol Label Switching ACH: Associated Channel TTL: Time-to-Live G-ACh: Generic Associated Channel GAL: Generic Associated Channel Label NTP: Network Time Protocol PTP: Precision Time Protocol PW: Pseudo-wire LSP: Label Switched Path OAM: Operations, Administration, and Maintenance 1.1.2. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Mirsky, et al. Expires April 24, 2014 [Page 3] Internet-Draft Residence Time Measurement October 2013 2. Residence Time Measurement Packet Loss and Delay Measurement for MPLS Networks [RFC6374] can be used to measure one-way or two-way end-to-end propagation delay over LSP or PW. But none of these metrics is useful for time syncronization across a network. For example, PTPv2 uses "residence time", time it takes for a PTPv2 packet to transit a node, not delay of propagation over a link connected to a port receiving the PTP event message. 3. G-ACh for Residence Time Measurement RFC 5586 [RFC5586] and RFC 6423 [RFC6423] extended applicability of PW Associated Channel (ACH) [RFC5085] to LSPs. G-ACh presents mechanism to transport OAM and other control messages and trigger their processing by arbitrary transient LSRs through controlled use of Time-to-Live (TTL) value. Packet format for Residence Time Measurement presented in Figure 1 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|Version| Reserved | RTM Channel | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Scratch Pad | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Payload | | | . . Figure 1: G-ACh packet format for Residence Time Measurement Version field is set to 0, as defined in RFC 4385 [RFC4385]. Reserved field must be set to 0 on trnsmit and ignored at reception. Residence Time Measurement (RTM) G-ACh - value to be allocated by IANA. Scratch pad - 8 octets long field that can be used to accumulate residence time the packet spends traversing the node. Payload - optional field. May be used to transport a packet of time synchronization protocol. 4. Theory of Operation An LSP ingress LSR, based on information collected through IGP extensions that are outside of scope of this document, select to use Mirsky, et al. Expires April 24, 2014 [Page 4] Internet-Draft Residence Time Measurement October 2013 use Residence Time Measurement G-ACh. The LSR then would use GAL and G-ACh header. The LSR will zero out Scratch Pad field and set TTL value so that TTL expiration will be at the next RTM capable downstream LSR. Upon expiration of RTM packet an LSR would substract local time value from the value in the Scratch Pad field and processes the packet according to label stack information. If the packet to be forwarded, the LSR will set TTL value so that the TTL expiration takes place at the next RTM-capable downstream LSR. The LSR adds local time value to the value in the Scratch Pad field as close to the start of packet transmition as possible. LSP terminating LSR may use value accumulated in the Scratch Pad field as time correction as it represent sum of Residence Time of all traveresed RTM capable LSR between end points of the LSP. For example, egress LSR may be PTP Boundary Clock syncronized to a Master Clock and as Slave Clock will use accumulated in the Scratch Pad Field value to update PTP's Correction Field. 5. IANA Considerations IANA is requested to reserve a new G-ACh as follows: +-------+----------------------------+---------------+ | Value | Description | Reference | +-------+----------------------------+---------------+ | X | Residence Time Measurement | This document | +-------+----------------------------+---------------+ Table 1: New Residence Time Measurement 6. Security Considerations Routers that support Residence Time Measurement are subject to the same security considerations as defined in [RFC5586] and [RFC6423]. 7. Acknowledgements TBD 8. References Mirsky, et al. Expires April 24, 2014 [Page 5] Internet-Draft Residence Time Measurement October 2013 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN", RFC 4385, February 2006. [RFC5085] Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, December 2007. [RFC5586] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic Associated Channel", RFC 5586, June 2009. [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, June 2010. [RFC6423] Li, H., Martini, L., He, J., and F. Huang, "Using the Generic Associated Channel Label for Pseudowire in the MPLS Transport Profile (MPLS-TP)", RFC 6423, November 2011. 8.2. Informative References [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS Networks", RFC 6374, September 2011. Authors' Addresses Greg Mirsky Ericsson Email: gregory.mirsky@ericsson.com John Drake Juniper Networks Email: jdrake@juniper.net Mirsky, et al. Expires April 24, 2014 [Page 6] Internet-Draft Residence Time Measurement October 2013 Keith Holleman Juniper Networks Email: holleman@juniper.net Stewart Bryant Cisco Systems Email: stbryant@cisco.com Alexander Vainshtein ECI Telecom Email: Alexander.Vainshtein@ecitele.com Mirsky, et al. Expires April 24, 2014 [Page 7]