PPP Working Group Pat R. Calhoun INTERNET DRAFT Ken Peirce Category: Internet Draft 3Com Corporation Title: draft-ietf-pppext-l2tp-ds-00.txt Date: February 1998 Layer Two Tunneling Protocol ''L2TP'' IP Differential Services Extension Status of this Memo This document is an Internet-Draft. 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. Internet-Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet-Drafts as reference material or to cite them other than as a ``working draft'' or ``work in progress.'' To learn the current status of any Internet-Draft, please check the 1id-abstracts.txt listing contained in the Internet-Drafts Shadow Directories on ds.internic.net, nic.nordu.net, ftp.nisc.sri.com, or munnari.oz.au. Abstract The L2TP document [1] defines the base protocol which describes the method of tunneling PPP [2] data. The L2TP base protocol does not address any Differential Services extensions. Since the market is reluctant to outsource dial access without any Quality of Service assurances, this draft addresses this problem by allowing each L2TP Data Session to be assigned an appropriate differential services indicator. Table of Contents 1.0 Introduction 1.1 Conventions 2.0 Quality of Service/Diferential Services Negotiation 2.1 Differential Sevices Indicator Exchange 3.0 Contacts 4.0 References Calhoun, Peirce expires August 1998 [Page 1]
INTERNET DRAFT February 1998 1.0 Introduction The L2TP protocol specification does not discuss Quality of Service/Differential Services in any way. The current state of the market has shown that many customers are reluctant to adopt L2TP without any quality of service assurances. This document will describe how two L2TP peers can negotiate a differential services indicator for a dial-in user. The mechanism defined in this document assumes that the Tunnel Initiator determines what the user's appropriate service level is and sends the value in either the SCCRQ or OCRQ messages. The Tunnel Terminator can respond to the message by stating what it believes is the user's appropriate service level. The values of the indicator supplied by the Tunnel Terminator will supercede those provided by the Tunnel Initiator if a difference is found. However, the Tunnel Terminator MUST NOT propose a higher differential service level than was proposed by the Tunnel Initiator. In the case where the Tunnel Terminator does not propose ANY indicator (which is infered by the absence of the QOS AVPs in either the SCCRP or OCRP) the Tunnel Initiator will assume no QOS is assigned to the session. A tunnel peer which violates the negotiated differential service level is liable to have it's tunnel shutdown. 1.1 Conventions The following language conventions are used in the items of specifi- cation in this document: o MUST, SHALL, or MANDATORY -- This item is an absolute requirement of the specification. o SHOULD or RECOMMEND -- This item should generally be followed for all but exceptional circumstances. o MAY or OPTIONAL -- This item is truly optional and may be followed or ignored according to the needs of the implementor. 2.0 Quality of Service/Diferential Services Negotiation This section will define the new AVPs which are required for the Quality of Service extension of the L2TP protocol. The AVPs allow designation of a Quality of Service level for a specific data channel. Calhoun, Peirce expires August 1998 [Page 2]
INTERNET DRAFT February 1998 2.1 Differential Sevices Indicator AVP The Differential Services indicator AVP is found in the IPv4 hear Type of Service octet. This is the second octet in the header. The actual bit interpretation of the IP Precedence and Type of Service bit fields is left to the appropriate documentation[2][3][4]. This document is concerned with defining a uniform exchange mechanism for the indicator only. The Differential Services Indicator AVP MAY be present in SCCRQ, SCCRP, OCRQ and OCRP. This message is used to inform the tunnel peer that a set of differential service indicator value SHOULD be used for all packets related to the data channel associated with the Tunnel and Call Identifiers in the L2TP header [1]. The presence of this AVP in the SCCRQ or OCRQ indicates that the tunnel initiator wishes to use a specific differential service indicator value on all data packets. However, the value found in the SCCRP or OCRP indicate the value which the Tunnel Terminator is willing to accept. However, the Tunnel Terminator MUST NOT propose a higher differential service level than was proposed by the Tunnel Initiator. A tunnel peer which violates the negotiated indicator value is liable to have it's tunnel shutdown. 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|1|0|0| Length | 43 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1 | Diff Serv Indicator Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This AVP MAY be present in the messages shown above. It is encoded with a Vendor ID of 43 (3Com Corporation) with the attribute set to 1, marked as optional, with the indicator value as data. This AVP SHOULD NOT be hidden and is optional. When present, the L2TP peer is indicating that differential services are to be used on IP packets within the session's data channel. 3.0 Contacts Pat R. Calhoun 3Com Corporation 1800 Central Ave. Mount Prospect, Il, 60056 Pat_Calhoun@mw.3com.com Calhoun, Peirce expires August 1998 [Page 3]
INTERNET DRAFT February 1998 (847) 342-6898 Ken Peirce 3Com Corporation 1800 Central Ave. Mount Prospect, Il, 60056 Ken_Peirce@mw.3com.com (847) 342-6894 4.0 References [1] K. Hamzeh, T. Kolar, M. Littlewood, G. Singh Pall, J. Taarud, A. J. Valencia, W. Verthein, W.M. Townsley, B. Palter, A. Rubens "Layer Two Tunneling Protocol (L2TP)", Internet draft, October 1997 [2] D. Clark, J. Wroclawski, "An Approach to Service Allocation in the Internet", draft-clark-diff-svc-alloc-00.txt, July 1997. [3] P. Ferguson, "Simple Differential Services: IP TOS and Precedence, Delay Indication, and Drop Preference,", draft-ferguson-delay-drop-00.txt, November 1997 [4] J. Heinanen, "Use of the IPv4 TOS Octet to Support Differential Services", draft-heinanen-diff-tos-octet-01.txt, November 1997 Calhoun, Peirce expires August 1998 [Page 4]
