Internet Draft Robert Ching John Chiong Sentient Networks April 1999 Expires: November 1999 Dynamic Bandwidth Management Using Resource Adjuster Cells STATUS OF THIS MEMO: This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. Distribution of this memo is unlimited. COPYRIGHT NOTICE: Copyright (C) The Internet Society (1999). All Rights Reserved. ABSTRACT: Dynamic bandwidth management using ATM Resource Adjuster Cells provides the capability to support fast effective end-to-end bandwidth control for IP traffic transported over an ATM backbone network. This feature can open up potential new services for Service Providers to offer dynamic service levels traffic agreements to their customers. By offering dynamic service levels, Service Providers can broaden their scope of service differentiation. For example, using dynamic bandwidth feature, Service Providers can offer their customers real-time video or multimedia transport capability across the networks. Using Dynamic Resource Adjuster Cells (DRACs), the network supporting it can quickly adjust bandwidth without taking down the ATM network connection and re-establishing it. In a fast changing dynamic environment, this dynamic adjuster capability makes a difference in both performance and scalability. Ching, Chiong [Page 1] Internet Draft Dynamic Bandwidth Management April 99 The DRACs are based on ATM Traffic Management RM cell format with the addition of dynamic bandwidth adjustment support parameters. The RAC parameters can relay bandwidth adjustment parameters to increase or decrease the bandwidth. We propose a framework using Dynamic Resource Adjuster Cell that can relay three parameters, they are bandwidth adjustment, group identification and priority status. Although DRAC is based on ATM Resource Management cell format, the same parameters can be used for non-ATM networks. This paper describes the ATM part only. In particular, the DRAC contains bandwidth adjustment percentage (BAP) indicating the percentage increment or decrement from the current bandwidth, a group identification (GID) that uniquely associates the connections within a group, and bandwidth bump priority (BBP) that can potentially bump or take bandwidth from lower priority circuits of the same group. The goal of this service is to accommodate applications that want to have more direct control of their network traffic flows. This draft addresses point-to-point dynamic bandwidth management, multipoint bandwidth management is left for future study. Table of Contents Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.0 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.0 Dynamic Bandwidth Management . . . . . . . . . . . . . . . . . 4 3.1 Bandwidth Adjustment Parameter . . . . . . . . . . . . . . 4 3.2 Group Identification . . . . . . . . . . . . . . . . . . . 4 3.3 Bandwidth Bump Priority . . . . . . . . . . . . . . . . . 4 4.0 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.0 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.0 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.0 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Ching, Chiong [Page 2] Internet Draft Dynamic Bandwidth Management April 99 1.0 Introduction Dynamic bandwidth management using ATM Resource Adjuster Control Cells provides the capability to support fast effective end-to-end bandwidth control for IP traffic transported over an ATM backbone network. This feature can open up potential new services for Service Providers to offer dynamic service levels traffic agreements to their customers. By offering dynamic service levels, Service Providers can broaden their scope of service differentiation. For example, using dynamic bandwidth feature, Service Providers can offer their customers real-time video or multimedia transport capability across the networks. Using Dynamic Resource Adjuster Control Cells (DRACs), the nodes supporting it can quickly adjust bandwidth without taking down the ATM network connection and re-establishing it. In a fast changing dynamic environment, this dynamic adjuster capability makes a difference in both performance and scalability. The DRACs are based on ATM Traffic Management RM cell format with the addition of dynamic bandwidth adjustment support parameters. The RAC parameters can relay bandwidth adjustment parameters to increase or decrease the bandwidth. We propose to use Dynamic Resource Adjuster Cell that can relay three parameters, they are bandwidth adjustment, group identification and priority status. Although DRAC cells are based on ATM Resource Management cell format, the same parameters can be used for non-ATM networks. This paper describes the ATM part only. In particular, the DRAC contains bandwidth adjustment parameter (BAP) indicating the percentage increment or decrement from the current bandwidth, a group identification (GID) that uniquely associates the connections within a group which is also known as a DRAC stream (see definition below), and bandwidth bump priority (BBP) that can potentially bump or take bandwidth from lower priority circuits of the same group. The goal of this service is to accommodate applications that want to have more direct control of their network traffic flows. This draft addresses point-to-point dynamic bandwidth management, multi-point bandwidth management is left for future study. 2.0 Definitions BAP: Bandwidth Adjustment Parameter BBP: Bandwidth Bump Priority DRAC: Dynamic Resource Adjuster Control DRAC Link: A bandwidth transmission medium between two DRAC Aware Nodes DRAC ATM Node: A DRAC aware ATM switch DRAC Stream: A group of DRAC connections with the same traffic characteristics. End-system DRAC Gateway: An end system that supports applications' side bandwidth control and can relay those bandwidth needs to a DRAC ATM node over a DRAC link. Ching, Chiong [Page 3] Internet Draft Dynamic Bandwidth Management April 99 GID: Group Identification. GID identifies a connection group. Intermediate DRAC Gateway: An intermediate node with non-ATM side bandwidth control and can relay those bandwidth needs to a DRAC ATM node over a DRAC link. 3.0 Dynamic Bandwidth Management Transport of IP over ATM network is becoming more common in Service Providers' networks of today. These IP over ATM networks are increasingly being used to provide services ranging from LAN interconnectivity to voice transport. Different ATM class of services are currently defined that can service Constant Bit Rate (CBR), real-time Variable Bit Rate (rt-VBR), non-real-time Variable Bit Rate (nrt-VBR), Available Bit Rate (ABR) and Undefined Bit Rate (UBR). Although these services can accommodate a large spectrum of IP traffic types, there are limitations and constraints in effectively supporting real-time and time-sensitive IP traffic with dynamic bandwidth characteristics. This proposal adds a capability that can enhance the support of real-time variable bandwidth IP traffic over ATM. In particular, the ability of end-to-end support for dynamic bandwidth control. The notion of this support of end-to-end is based on the end-system ability to request the change and the transport network ability to honor the change in a dynamic manner. The following diagram depicts the components involved for this support. ___ _____ _____ ______ _____ ___ | | | |-----| |_______| |-----| | | | |ESs|===|EDG |-----|DSR |_______| DSR |-----|EDG |===|ESs| |___| |_____|-----|_____| |______|-----|_____| |___| A B C D E ESs End Systems EDG End System DRAC Gateway DSR DRAC Aware Switch-Router A,E End System to ESDG Links B,D EDG to DSR Links (EDRAC Links) C DSR to DSR Links (DDRAC Links) The way an end-system requests for dynamic bandwidth is not specified in this specification. Some of the examples are: Bandwidth Control APIs, Bandwidth Control Policy or based on Bandwidth Configuration. Note that ESs and EDG can be implemented as one system, or as separate systems. When an EDG receives a change of bandwidth request from an ES, the ESDG will send a DRAC cell that reflects this change to DSR over the EDRAC link. DSR will process the requested changes and then relay Ching, Chiong [Page 4] Internet Draft Dynamic Bandwidth Management April 99 the bandwidth changes downstream as necessary. The following sections 3.1, 3.2 and 3.3 describe the DRAC cell bandwidth parameters in more details. Another type of DRAC gateway is the Intermediate-system DRAC Gateway. An IDG supports non-ATM side bandwidth usage and decides when to make bandwidth modification requests to DSR. How IDGs interface within the non-ATM network or get the bandwidth information is implementation specifics. One way of doing it will be to support resource reservation type of protocols. 3.1 Bandwidth Adjustment Parameter (BAP) This parameter indicates bandwidth adjustment. This parameter is a percentage increment or decrement based on the current bandwidth for the connection. 3.2 Group Identification (GID) This parameter indicates the group that the link belongs to. Typically this parameter will not change once it is assigned. 3.3 Bandwidth Bump Priority (BBP) This parameter indicates the relative priority of this connection. A higher BBP priority can essentially take bandwidth away from lower priority connections in the same GID. Note that, feedback mechanisms of bandwidth changes are not currently part of this specification. The control and potential impact of bandwidth bumping is left to Applications' control. 4.0 Summary In summary we make these proposals: (1) End-system DRAC Gateway, or EDG, supports applications' bandwidth demand and decides when to make bandwidth modification requests to DSR. How EDGs interface with applications or get the bandwidth information is implementation specifics. One way of doing it will be to use dynamic bandwidth control APIs. EDGs manage and control bandwidth-in-use, and bandwidth allocation thresholds for applications. (2) DRAC switch/router, or DSR, supports dynamic bandwidth control based on DRAC cells. DSR interfaces with EDGs and IDGs at one end, and typcially has trunk interfaces to another DSR. A DSR can aggregate access side bandwidth over the trunk links. (3) Intermediate-system DRAC Gateway, or IDG, supports non-ATM side bandwidth usage and decides when to make bandwidth modification requests to DSR. How IDGs interface within the non-ATM network or get the bandwidth information is implementation specifics. One way of doing it will be to support some form of resource reservation protocol. (3) DRAC format, based on ATM RM cell and consists of three parameters, they are Bandwidth Adjustment Parameter (BAP), Group Identification (GID) and Bandwidth Bump Priority (BBP). Ching, Chiong [Page 5] Internet Draft Dynamic Bandwidth Management April 99 This draft addresses point-to-point QoS resource management, multi-point QoS resource management is left for future study. 5.0 References [ADFFT98] Anderson, L., Doolan, P., Feldman, N., Fredette, A., Thomas, B., LDP Specification, IETF draft-ietf-mpls-ldp-01.txt, August 1998. [B98] Bernet, Y., et. al., A Framework for Differentiated Services, IETF draft-ietf-diffserv-framework-01.txt, October 1998. [M98] Moy, John, OSPF Version 2, IETF RFC 2328, April 1998. [RVC99] Rosen, E., Viswanathan, A., Callon, R., Multiprotocol Label Switching Architecture, IETF draft-ietf-mpls-arch-04.txt, February 1999. [S95] Steenstrup, M., Editor, Routing in Communications Networks, Prentice-Hall, 1995. 6.0 Abbreviations BW Bandwidth BWIP Bandwidth in Progress BWOF Bandwidth Offered BWOV Bandwidth Overflow DIFFSERV Differentiated Services HL Heavily Loaded IETF Internet Engineering Task Force IP Internet Protocol LDP Label Distribution Protocol LSP Label Switched Path MPLS Multiprotocol Label Switching OSPF Open Shortest Path First PSTN Public Switched Telephone Network QoS Quality of Service TLV Type/Length/Value ToS Type of Service VN Virtual Network 7.0 Authors' Addresses Robert Ching John Chiong Sentient Networks 630 Alder Drive Milpitas, CA 95035 ching@sentient.com chiong@sentientnet.com Ching, Chiong [Page 6] Internet Draft Dynamic Bandwidth Management April 99