Network Working Group H. Long Internet Draft M. Ye Intended status: Standards Track Huawei Technologies Co., Ltd. Expires: August 2013 February 18, 2013 Multi-Segment Pseudowire Signaling with Availability Information draft-long-pwe3-ms-pw-availability-01.txt Abstract This document describes a signaling mechanism for setting up a multi-segment pseudowire between different domains in case that at least one domain has the feature that bandwidth capacity is variable for different availability values. The signaling mechanism is an extension on the multi-segment pseudowire signaling [DYN-MS-PW]. 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), 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on August 18, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. Long & Ye Expires August 18, 2013 [Page 1] Internet-Draft draft-long-pwe3-ms-pw-availability-01 February 2013 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. Table of Contents 1. Introduction ................................................ 2 2. LDP Signaling ............................................... 3 3. Security Considerations...................................... 4 4. IANA Considerations ......................................... 4 5. References .................................................. 4 5.1. Normative References.................................... 4 5.2. Informative References.................................. 4 6. Acknowledgments ............................................. 5 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 RFC-2119 [RFC2119]. 1. Introduction [RFC5659] describes the architecture of multi-segment pseudowire. The LDP signaling mechanism for setting up multi-segement pseudowire is described by [DYN-MS-PW]. The mechanism introduces a pseudowire bandwidth TLV for PSN tunnel selection. In some networks, there may be some links with variable bandwidth. For example, in mobile backhaul network, microwave links are very popular for providing connection of last hops. In case of heavy rain, to maintain the link connectivity, the microwave link will lower the modulation format since demodulating lower modulation format need lower signal-to-noise ratio (SNR). This is called adaptive modulation technology. However, lower modulation format also means lower link bandwidth. Similarly the cooper links may change their link bandwidth due to external interference. Long & Ye Expires August 18, 2013 [Page 2] Internet-Draft draft-long-pwe3-ms-pw-availability-01 February 2013 The parameter, availability [G.827, F.1703], is often used to describe the link capacity during network planning. A link may provide different bandwidth for different availability requirement In this case, a LSP across the links should include multiple bandwidth portions with different availability guarantee. As a result, only PW bandwidth requirement information is not enough for the multi-segment pseudowire setup. An optional PW availability TLV is introduced in this document for providing enough information for S-PE to selecting PSN tunnel. 2. LDP Signaling 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|0| Availability TLV(TBD) | TLV Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Availability requirement | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 - PW Availability TLV The optional PW availability TLV described by Figure 1 includes an availability requirement field which is a 32-bit floating point number. This field describes the availability requirement for the multi-segment pseudowire. The value can be inherited from the availability requirement of the emulated service. It should be smaller than 1. When an S/T-PE receives a PW availability TLV and a PW bandwidth TLV, it will search for an PSN tunnel which can satisfy the bandwidth requirement with the availability requirement. Once the PW next hop is selected, the S/T-PE MUST request the appropriate resources which can guarantee the required availability from the PSN. In the case where PSN resources towards the next hop cannot satisfy the bandwidth request with the specified the availability requirement; the following procedure MUST be followed: -i. The PSN MAY allocate more QoS resources, e.g. Bandwidth with required availability guranttee, to the PSN tunnel. -ii. The S-PE MAY attempt to setup another PSN tunnel to accommodate the new PW QoS requirements. -iii. If the S-PE cannot get enough resources to setup the segment in the MS-PW a label release MUST be returned to the Long & Ye Expires August 18, 2013 [Page 3] Internet-Draft draft-long-pwe3-ms-pw-availability-01 February 2013 previous hop with a status message of "Bandwidth resources unavailable" In the latter case, the T-PE receiving the status message MUST also withdraw the corresponding PW label mapping for the opposite direction if it has already been successfully setup. 3. Security Considerations This document does not introduce new security considerations. 4. IANA Considerations TBD. 5. References 5.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5659] Bocci, M., Bryant, S., "An Architecture for Multi-Segment Pseudowire Emulation Edge-to-Edge", RFC 5659, October 2009. [DYN-MS-PW] Martini, L., Bocci, M., Balus, F., "Dynamic Placement of Multi Segment Pseudo Wires", draft-ietf-pwe3-dynamic-ms- pw-16, October, 2010 [G.827] ITU-T Recommendation, "Availability performance parameters and objectives for end-to-end international constant bit- rate digital paths", September, 2003. [F.1703] ITU-R Recommendation, "Availability objectives for real digital fixed wireless links used in 27 500 km hypothetical reference paths and connections", January, 2005. 5.2. Informative References Long & Ye Expires August 18, 2013 [Page 4] Internet-Draft draft-long-pwe3-ms-pw-availability-01 February 2013 6. Acknowledgments Authors' Addresses Hao Long Huawei Technologies Co., Ltd. No.1899,Xiyuan Avenue, Hi-tech Western District Chengdu 611731, P.R.China Email: longhao@huawei.com Min Ye Huawei Technologies Co., Ltd. No.1899,Xiyuan Avenue, Hi-tech Western District Chengdu 611731, P.R.China Email: amy.yemin@huawei.com Long & Ye Expires August 18, 2013 [Page 5]