Internet Engineering Task Force J. Manner (ed.) Internet-Draft X. Fu (ed.) Expires: April, 2003 October 28, 2002 Analysis of Existing Quality of Service Signaling Protocols 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. This Internet-Draft will expire in April, 2003. Copyright Notice Copyright (C) The Internet Society (2000). All Rights Reserved. All comments to this work should be directec to the NSIS mailing at nsis@ietf.org. Abstract This document presents a review of existing protocols for signalling the Quality of Service requirements of flows to nodes in an IP network. Protocols are reviewed independently and not compared against the NSIS requirements document nor to RSVP itself. The purpose is to learn from existing work and to avoid common misconceptions about the protocols. A further goal is to avoid to redesign ideas already implemented in another protocol. Manner et al Expires April 2003 [Page 1] Internet-Draft Analysis of QoS Signaling October 2002 TODO items - Evaluate the rest of the protocols - Add more protocols? Remove protocols? Table of Contents 1 Introduction ................................................. 3 2 The Resource Reservation Protocol ............................ 4 2.1 Extensions to RSVP ......................................... 5 2.2 Reservation functionality .................................. 6 2.3 Processing Overhead ........................................ 7 2.4 Bandwidth Consumption ...................................... 8 2.5 Mobility Support ........................................... 8 2.6 Security ................................................... 9 2.7 Deployment Issues .......................................... 9 2.8 Conclusions ................................................ 10 3 YESSIR ....................................................... 11 3.1 Reservation Functionality .................................. 11 3.2 Processing Overhead ........................................ 12 3.3 Bandwidth Consumption ...................................... 12 3.4 Mobility Support ........................................... 12 3.5 Security ................................................... 12 3.6 Deployment Issues .......................................... 12 3.7 Conclusions ................................................ 12 4 Boomerang .................................................... 12 4.1 Reservation Functionality .................................. 13 4.2 Processing Overhead ........................................ 13 4.3 Bandwidth Consumption ...................................... 13 4.4 Mobility Support ........................................... 13 4.5 Security ................................................... 13 4.6 Deployment Issues .......................................... 13 4.7 Conclusions ................................................ 14 5 Other Protocols .............................................. 14 5.1 INSIGNIA ................................................... 14 5.2 Mobile RSVP ................................................ 15 5.3 BGRP ....................................................... 15 5.4 ST-II ...................................................... 15 5.5 The ITSUMO Framework ....................................... 16 6 Summary ...................................................... 17 7 Security Considerations ...................................... 17 8 Contributors ................................................. 17 9 Acknowledgement .............................................. 17 10 References .................................................. 17 11 Author's Addresses .......................................... 20 Manner et al Expires April 2003 [Page 2] Internet-Draft Analysis of QoS Signaling October 2002 1. Introduction The aim of this document is to present existing mature protocols and architectures for signalling the Quality of Service (QoS) requirements of flows to nodes in an IP network. The various protocols are reviewed independently and without comparing against the NSIS requirements document, because the protocols have already been designed before the work on present requirements was initialized. Neither do we want to make any comparison of protocols against RSVP because this would of little value - all protocols have their own research backgrounds and targets and therefore do things differently. We also hope that the NSIS Working Group can learn from existing work and we can avoid common misconceptions about the protocols. A further goal is to avoid to redesign ideas already implemented in an existing protocol. There have been a number of historic attempts in delivering QoS or generic signaling into the Internet. In the early years, multicast was believed to be going to be popular to majority of communications, hence RSVP and earlier ST-II were designed in a way which is multicast-oriented. ST-II was developed as a reservation protocol for point-to-multipoint communication. However, since it is sender- initiated, it does not scale with the number of receivers in a multicast group. It is complex and since every sender needs to set up its own reservation, the total amount of reservation state is large. RSVP was then designed to provide support for multipoint-to- multipoint reservation setup in a more efficient way, however its complexity, scalability and ability to meet new requirements have been criticized. YESSIR [PaSc98] and Boomerang [FNM+99] are examples of protocols designed after RSVP. Both protocols were meant to be simpler than RSVP. YESSIR is an extension to RTCP, while Boomerang is used with ICMP. Previously, there has been a lot of work targeted at creating a new signalling protocol for resource control. Istvan Cselenyi suggested to request for QoSSIG BOF in IETF#47 (http://www-nrg.ee.lbl.gov/diff- serv-arch/msg05055.html), for identifying problems in QoS signaling, but failed. Some people argued, "in many ways, RSVP improved upon ST-2, and it did start out simpler, but resulting a design with complexity and scalability", while some others thought it is "new knowledge and requirements" that made RSVP insufficient (http://www- nrg.ee.lbl.gov/diff-serv-arch/msg05066.html), and there is no simpler way to handle the same problem as RSVP. Michael Welzl organized a special session "ABR to the Internet" in SCI 2001, and gathered some inputs for requesting an "ABR to the Internet" BOF in IETF#51, which was intended to introduce explicit rate feedback related mechanisms for the Internet (e2e, edge2edge) but failed because of "missing community interest" (http://www.tk.uni-linz.ac.at/~michael/abr-internet/). OPENSIG (http://comet.columbia.edu/opensig/) has been involved in the Manner et al Expires April 2003 [Page 3] Internet-Draft Analysis of QoS Signaling October 2002 Internet signaling for years. Ping Pan initiated a SIGLITE (http://www.cs.columbia.edu/~pingpan/projects/siglite.html) BOF mailing list to investigate light-weight Internet signaling. Finally, NSIS BOF was successful and the NSIS WG was formed. The most mature and original protocols are presented in their own sections and other QoS signalling protocols are presented in later subsections. 2. The Resource Reservation Protocol RSVP (the Resource ReServation Protocol) [RSVP] [RFC2205] [BEBH96] has evolved from ST-II to provide end-to-end QoS signaling services for application data streams. Hosts use RSVP to request a specific quality of service (QoS) from the network for particular application flows. Routers use RSVP to deliver QoS requests to all routers along the data path. RSVP also can maintain and refresh states for a requested QoS application flow. This section shortly reviews the RSVP basic model and its extensions. RSVP tries to be well-fit in the Integrated Services (IntServ) [RFC2210], [BEBH96] architecture with certain modularity and scalability. The design of the RSVP protocol distinguished itself by a number of fundamental ways, particularly, soft state management, two-pass signaling message exchanges, receiver-based resource reservation and separation of QoS signaling from routing. RSVP Signaling Model: The RSVP signaling model is based on a special handling of multicast. The sender of a multicast flow advertises the traffic characteristics periodically to the receivers via "Path" messages. On receipt of an advertisement, a receiver may generate a "Resv" message to reserve resources along the flow path from the sender. Receiver reservations may be heterogeneous. To accommodate the multipoint-to-multipoint multicast applications, RSVP was designed to support a vector of reservation attributes called the "style". A style describes whether all senders of a multicast group share a single reservation and which receiver is applied. The "Scope" object additionally provides the explicit list of senders. Soft State: Because the number of receivers in a multicast flow is likely to change, and the flow of delivery paths might change during the life of an application flow, RSVP takes a soft-state approach in its design, creating and removing the protocol states in routers and hosts incrementally over time. RSVP sends periodic refresh messages to maintain its state and to recover from occasional lost messages. In the absence of refresh messages, the RSVP states automatically time out and are deleted. Two-pass Signaling Message Exchanges: The receiver in an application flow is responsible for requesting the desired QoS from the sender. To do this, the receiver issues an RSVP QoS request on behalf of the local application. The request propagates to all routers in reverse direction of the data paths toward the sender. In this process, RSVP Manner et al Expires April 2003 [Page 4] Internet-Draft Analysis of QoS Signaling October 2002 requests might be merged, resulting in a protocol that scales well when there are a large number of receivers. Receiver-based Resource Reservation: Receiver-initiation is critical for RSVP to setup multicast sessions with a large number of heterogeneous receivers. A receiver initiates a reservation request at a leaf of the multicast distribution tree, traveling towards the sender. Whenever a reservation is found to already exist in a node in the distribution tree, the new request will be merged with the existing reservation. This could result in fewer signalling operations for the RSVP nodes in the multicast tree close to the sender, but introduce a restriction to receiver-initiation. Separation of QoS Signaling from Routing: RSVP messages follow normal IP routing. RSVP is not a routing protocol, but rather is designed to operate with current and future unicast and multicast routing protocols. The routing protocols are responsible for choosing the routes to use to forward packets, and RSVP consults local routing tables to obtain routes. RSVP is responsible only for reservation setup along a data path. 2.1. Extensions to RSVP There have been various extensions to enhance the basic RSVP protocol: policy, cryptographic authentication, operation over 802.x and ATM, aggregation, tunneling, refresh overhead reduction, diagnostics, RSVP-TE, DCLASS, null service, proxy, mobility schemes, etc., there have been a large amount of efforts towards a globe-wide Internet QoS deployment based on RSVP since its development. Note: only Standards Track RFCs are discussed below; informational and BCP RFCs (e.g., RFC2998) and I-Ds (e.g., proxy) are not covered here. [RFC2749] specifies the usage of COPS policy services in RSVP environments. [RSVP2750] specifies the standard format of POLICY_DATA objects and RSVP handling of policy events. [RSVP2751] specifies a preemption priority policy element (PREEMPTION_PRI) for use by RSVP POLICY_DATA Object. L-N. Hamer, et al, draft-ietf-rap-rsvp-authsession-04 (being approved by IESG) describes how an RSVP session is authorized by a host and provides the host with encoded session authorization information as a POLICY_DATA object. [RFC2380] presents the implementation requirements for running RSVP over ATM switched virtual circuits (SVCs). [RFC2814] introduces an RSVP LAN_NHOP address object that keeps track Manner et al Expires April 2003 [Page 5] Internet-Draft Analysis of QoS Signaling October 2002 of the next L3 hop as the PATH message traverses an L2 domain between two L3 entities (RSVP PHOP and NHOP nodes). Both layer-2 and layer-3 addresses are included in the LAN_NHOP; the RSVP_HOP_L2 object is used to include the Layer 2 address (L2ADDR) of the previous hop, complementing the L3 address information included in the RSVP_HOP object (RSVP_HOP_L3 address). To provide sufficient information for debugging or resource management, RSVP diagnostic messages (DREQ and DREP) are defined in [RFC2745] to collect and report RSVP state information along the path from a receiver to a specific sender. [RFC2746] describes an IP tunneling enhancement mechanism that allows RSVP to make reservations across all IP-in-IP tunnels, basically, by way of recursively applying RSVP over the tunnel portion of the path. To reduce the refresh volume and maintain reliability, [RFC2961] defines a Bundle message to reduce overall message handling load, a MESSAGE_ID object to reduce refresh message processing by allowing the receiver to more readily identify an unchanged message, and a MESSAGE_ACK object to detect message loss and support reliable RSVP message delivery on a per hop basis. [RFC3175] allows to install one or more aggregated reservations in an aggregation region, thus the number of individual RSVP sessions can be reduced. [RFC3209] specifies the extension to RSVP for establishing explicitly routed LSPs in MPLS networks using RSVP as a signaling protocol. An EXPLICIT_ROUTE object is incorporated into RSVP Path messages, encapsulating a concatenation of hops which constitutes the explicitly routed path. Using this object, the paths taken by label- switched RSVP-MPLS flows can be pre-determined, independent of conventional IP routing. Section 5 of RFC3270 further specifies the extensions to RSVP to establish LSPs supporting DiffServ in MPLS networks, introducing a new DIFFSERV Object (applicable in the Path messages) and using pre- configured or (e.g. RFC3270) signaled "EXP<-->PHB mapping". 2.2. Reservation functionality RSVP carries the QoS data of the request through the network, visiting each node along the data path. To make a resource reservation at a node, the RSVP module communicates with two local decision modules, admission control and policy control. Admission control determines whether the node has sufficient available resources to supply the requested QoS. Policy control determines whether the user has administrative permission to make the reservation. If either check fails, the RSVP module returns an error notification to the application process that originated the request. If both checks succeed, the RSVP module sets parameters in a packet Manner et al Expires April 2003 [Page 6] Internet-Draft Analysis of QoS Signaling October 2002 classifier and packet scheduler to obtain the desired QoS. The definition of the required resources is not part of the RSVP standard, but commonly the IntServ specifications for Controlled Load and Guaranteed Services are used. RSVP allows for unicast and multicast reservations. Various filtering rules may be used to identify flows belonging to a reservation - commonly the 5-tuple is used. RFC 2207 [RFC2207] specifies an RSVP extension to use the IPSEC SPI (Security Parameter Index), in place of the UDP/TCP-like ports, so that data flows containing IPSEC protocols can be controlled at a granularity similar to what is already specified for UDP and TCP. The IPv6 Flow Label can also be used as a key in the filters. Furthermore, reservations may be distinct or shared by several senders. RFC2996 [RFC2996] introduces a DCLASS Object to carry Differentiated Services Code Points (DSCPs) in RSVP message objects. If the network element determines that the RSVP request is admissible to the diff- serv network, one or more DSCPs corresponding to the behavior aggregate are determined, and will be carried by the DCLASS Object added to the RESV message upstream towards the RSVP sender. For some applications, service parameters are specified by the network, not by the application (e.g. ERP applications). The Null Service [RFC2997] allows applications to identify themselves to network QoS policy agents using RSVP signaling, but does not require them to specify resource requirements. QoS policy agents in the network respond by applying QoS policies appropriate for the application (as determined by the network administrator). The RSVP sender offers the new service type, 'Null Service Type' in the ADSPEC that is included with the PATH message. A new TSpec corresponding to the new service type is added to the SENDER_TSPEC. In addition, the RSVP sender will typically include with the PATH message policy objects identifying the user, application and sub-flow, which will be used for network nodes to manage the correspondent traffic flow. 2.3. Processing Overhead RSVP scales in that it supports large multicast groups, at the cost of high complexity in dealing with multicast in its basic protocol. While the RSVP protocol is also able to make unicast reservations, it was designed specifically and optimally for multicast. This important RSVP design consideration leads to the fact that, even for unicast applications, a full-fledged set of features for supporting multicast is still needed, mainly: reservation styles and scope object, receiver-initiated reservation, state management in routers, killer problems and blockade state handling. A detailed analysis of RSVP regarding multicast can be found in [Fu02]. [RaNa98] also identified the issue of inefficient resource reservation resulting from decentralized multicast routing. By way of aggregated RSVP [RFC3175] the complexity (in terms of number of states and needed processing overhead) decreases, but still Manner et al Expires April 2003 [Page 7] Internet-Draft Analysis of QoS Signaling October 2002 depends on the number of (de-)aggregators and topology, which may be more than marginal, e.g., in case of many edge nodes or meshed way of communications through the aggregate region, and remains complexity in dealing with multicast. In fact, many signaling scenarios do not need multicast in reality, e.g., typical DiffServ edge router resource reservation setup. Some multicast protocols (e.g., PIM-SM [RFC2362]) even consider multicast as a function built on top of unicast routing rather than as an integral part of it. Since a signaling protocol would typically traverse along a number of nodes in the Internet, there is a need to keep the mandatory components of the signaling protocol as simple as possible, in order to provide a simpler but adequate signaling service to various non-multicast signaling scenarios. Still, for example, the implementation of the daemon can have a huge effect on the scalability. In [KaSh01], the authors show that their RSVP daemon is able to handle much more flows than the de-facto ISI RSVP daemon implementation. Furthermore, the scalability concern commonly associated with RSVP are more or less subject to individual's views on what "scalability" is. 2.4. Bandwidth Consumption (The frequency and size of the RSVP signaling messages.) During the RSVP setup and refresh process, typically there is a two-pass message exchange between the sender and the receiver group. Since the refreshment is hop by hop, bandwidth consumption for RSVP could be reduced, but may result in more error/failure event handling. 2.5. Mobility Support Two issues raise concern when RSVP is used by a mobile node (MN): the reservation identifier and reservation refresh. When an MN changes locations, it may need to change one of its assigned IP address. An MN may have an IP address by which it is reachable by nodes outside the access network and an IP address used to support local mobility management. Depending on the mobility management mechanism, a handover may force a change in any of these addresses. As a consequence the filters associated with a reservation may not identify the flow anymore and the resource reservation is lost, until a refresh with a new set of filters is initialized. The second issue is about following the movement of a mobile node. RFC2205 defines that Path messages can perform a local repair of reservation paths. When the route between the communicating end hosts changes, a Path message will set the state of the reservation on the new route and a subsequent Resv message will make the resource reservation. Therefore, by sending a Resv message a host cannot alone update the reservation, and thus perform a local repair, before a Path message has passed. Also, in order to provide fast adaptation to Manner et al Expires April 2003 [Page 8] Internet-Draft Analysis of QoS Signaling October 2002 routing changes without the overhead of short refresh periods, the local routing protocol module can notify the RSVP process of route changes for particular destinations. The RSVP process should use this information to trigger a quick refresh of state for these destinations, using the new route (Chapter 3.6, RFC2205). However, not all local mobility protocols, or even Mobile IP, affect routing directly in routers, and thus mobility may not be noticed at RSVP routers. Thus, it may take a relatively long time before a reservation is refreshed following a handover. The interactions of RSVP and Mobile IP have been well documented in [Thom01]. 2.6. Security To allow a process on a system to securely identify the owner and the application of the communicating process (e.g. user id) and convey this information in RSVP messages (PATH or RESV) in a secure manner, [RFC2752] specifies the encoding of identities as RSVP POLICY_DATA Object. To provide hop-by-hop integrity and authentication of RSVP messages, RSVP message may contain an INTEGRITY object ([RFC2747]) using a keyed cryptographic digest technique which assumes that RSVP neighbors share a secret. (BTW - [RFC3097] updates [RFC2747] to resolve a duplication of RSVP message types.) The security issues have been well analyzed in [Tsch02]. 2.7. Deployment Issues As a well-acknowledged protocol in the Internet, RSVP is being more and more expected to provide a more generic service for various signaling applications. However, RSVP messages were designed in a way to optimally support end-to-end QoS signaling. To meet with the increasing demand for a signaling protocol to also operate in host- to-edge and edge-to-edge ways, and serve for some other signaling purposes in addition to end-to-end QoS signaling, RSVP needs to be developed more flexible and applicable for more generic signaling. RSVP proxies [BEGD02] extends RSVP by being able to originates or receive the RSVP message on behalf of the end node(s), so that applications may still benefit from reservations that are not truly end-to-end. However, there are certainly scenarios where an application would want to explicitly convey its non-QoS purposed (as well as QoS) data from a host into the network, or from an ingress node to an egress node of an administrative domain, but it must do so without burdening the network with excess messaging overhead. Typical examples are an end host desiring a firewall service from its provider's network and MPLS label setup within an MPLS domain. RSVP requires support from network routers and user space Manner et al Expires April 2003 [Page 9] Internet-Draft Analysis of QoS Signaling October 2002 applications. Domains not supporting RSVP are traversed transparently. Unfortunately, like other IP options, RSVP messages implemented by way of IP alert option may result in themselfs being dropped by some routers [FrJo02]. Although applications need to be built with RSVP libraries, one article presents a mechanism that would allow any host to benefit from RSVP mechanisms without applications awareness [MHS02]. A somewhat similar deployment benefit can be gained from the Localized RSVP [MSK+02]. The draft presents the concept of local RSVP-based reservation that can be used to trigger reservation within an access network alone. In those cases, an end-host may request QoS from its own access network without the co-operation of a correspondent node outside the access network. A proxy node responds to the messages sent by the end host and enables both upstream and downstream reservations. Furthermore, the scheme allows for faster reservation repairs following a handover by triggering the proxy to initiate an RSVP local repair. Still, in end-hosts which are low in processing power and functionality, having an rsvp daemon running and taking care of the signalling may introduce unnecessary overhead. One article [Kars01] proposes to create a remote API so that the daemon would in fact be running on the end-host's default router and the end-host application would send its requests to that daemon. Another potential problem lies in the limited sized of signaled data due to the limitation of message size. RSVP message must fit entirely into a single non-fragmented IP datagram. Bundle messages ([RFC2961]) may be as large as an IP datagram, since they may be fragmented. This means a maximum size of 64K. 2.8. Conclusions The design of RSVP was originally targeted at multicast applications. The result has been that the message processing within nodes is somewhat heavy, mainly due to flow merging. Still, merging rules could not appear in the specification as they are QoS-specific. RSVP has a comprehensive set of filtering rules (WF,FF, shared) and is not tied to certain QoS objects (RSVP is not tied to IntServ GS/CL specifications). Objects were designed to be modular, but Xspecs (TSpec, etc) are more or less QoS-specific and should be more generalized; there is no clear layering/separation between the signaled data and signaling protocol. RSVP uses a soft state mechanism to maintain states and allows each node to define its own refresh timer. The protocol is also independent of underlying routing protocols. Still, in mobile networks the movement of the mobile nodes may not properly trigger a reservation refresh for the new path and therefore a mobile node may be left without a reservation up to the length of the refresh timer. Furthermore, RSVP does not work properly with changing end-point Manner et al Expires April 2003 [Page 10] Internet-Draft Analysis of QoS Signaling October 2002 identifiers, that is, if one of the IP addresses of a mobile node changes, the filters may not be able to identify the flow that had a reservation. From the security point of view, RSVP does provide the necessary building blocks for deploying the protocol in various environments. Still, one major problem of RSVP security is that no key distribution mechanism is provided. Finally, since the publication of the RSVP standard, tens of extensions have emerged that allow for much wider deployment than RSVP was originally designed for, as for instance, the Subnet Bandwidth Manager, the NULL service type, aggregation, operation over tunneling and MPLS as well as diagnostic messages. Domains not supporting RSVP are traversed transparently by default. Unfortunately, like other IP options, RSVP messages implemented by way of IP alert option may result in themselves being dropped by some routers. Also, the maximal size of RSVP-signaled data is limited. 3. YESSIR YESSIR (YEt another Sender Session Internet Reservations) [PaSc98] is a resource reservation protocol that seeks to simplify the process of establishing reserved flows while preserving many unique features introduced in RSVP. Simplicity is measured in terms of control message processing, data packet processing, and user-level flexibility. Features such as robustness, advertising network service availability and resource sharing among multiple senders are also supported in the proposal. The proposed mechanism generates reservation requests by senders to reduce the processing overhead. It is built as an extension to the Real-Time Transport Control Protocol (RTCP), taking advantages of Real-Time Protocol (RTP). YESSIR also introduces a concept called partial reservation. 3.1. Reservation Functionality YESSIR was designed for one-way, sender-initiated end-to-end resource reservation. It also uses soft state to maintain states. It supports resource query (similar to RSVP diagnosis message), advertising (similar to RSVP Adspec), shared reservation, partial reservations and flow merging. To support multicast, YESSIR simplies the reservation styles to individual and shared reservation styles. Individual reservations are made separately for each sender, whereas shared reservations allocate resources that can be used by all senders in an RTP session. Unlike RSVP supports shared reservation (SE and WF styles) from the receiver's direction, YESSIR handles the shared reservation style from the sender's direction, thus new receivers can re-use the Manner et al Expires April 2003 [Page 11] Internet-Draft Analysis of QoS Signaling October 2002 existing reservation of the previous sender. 3.2. Processing Overhead In [PaSc00], it was proved that YESSIR one-pass reservation model has better performance and lower processing cost, comparing with a regular two-way signaling protocol. 3.3. Bandwidth Consumption The bandwidth consumption of YESSIR is somewhat lower than that of, for example, RSVP, because it does not require additional IP and transport headers. Bandwidth consumption is limited to the extension header size. 3.4. Mobility Support YESSIR does not have any particular support for mobility. The same issues that were identified with RSVP apply. 3.5. Security The security of YESSIR relies on RTP/RTCP security measures. 3.6. Deployment Issues YESSIR requires support in applications since it is an integral part of RTCP. Similarly, it requires network routers to inspect RTCP packets to identify reservation requests and refreshes. Routers unaware of YESSIR forward the RTCP packets transparently. 3.7. Conclusions 4. Boomerang Boomerang [FNM+99] is a light-weight resource reservation protocol for IP networks. The protocol has only one message type and a single signaling loop for reservation set-up and tear-down, has no requirements on the far end node, but, instead, concentrates the intelligence in the Initiating Node (IN). In addition, the Boomerang protocol allows for sender- or receiver- Manner et al Expires April 2003 [Page 12] Internet-Draft Analysis of QoS Signaling October 2002 oriented reservations and resource query. Flows are identified with the common 5-tuple and the QoS can be specified with various means, eg. service class and bit rate. Boomerang messages are in the initial implementation transported in ICMP ECHO / REPLY messages. 4.1. Reservation Functionality Boomerang can only be used for unicast sessions, no support for multicast exists. The requested QoS can be specified with various methods and both ends of a communication session can make a reservation for their transmitted flow. 4.2. Processing Overhead The authors of Boomerang show in [FNS02] that the processing of the protocol is considerably lower than with the ISI RSVP daemon implementation. 4.3. Bandwidth Consumption Boomerang messages are quite short and consume a relatively low amount of link bandwidth. 4.4. Mobility Support The same issues that were identified with RSVP apply with Boomerang. 4.5. Security No mechanisms for providing message integrity or user identification have been presented. 4.6. Deployment Issues The Boomerang protocol has similar deployment issues as any host- network-host protocol. It requires an implementation at both communicating nodes and in routers. Boomerang-unaware routers should be able to forward Boomerang messages transparently. Manner et al Expires April 2003 [Page 13] Internet-Draft Analysis of QoS Signaling October 2002 4.7. Conclusions Boomerang seems to be a very lightweight protocol and efficient in its own scenarios. Still, the apparent low processing overhead and bandwidth consumption results from the limited functionality. No support for multicast or any security features are present which allows for a different functionality than RSVP, which the authors like to compare Boomerang to. 5. Other Protocols This section presents shortly other signalling protocols designed to carry resource information for flows. 5.1. INSIGNIA INSIGNIA [PaSc00] has been developed at the Columbia University and is proposed as a very simple signaling mechanism for supporting QoS in mobile ad-hoc networks. It avoids the need for separate signaling by carrying the signaling along with the data in IP packets using IP packet header options. This approach, known as "in-band signaling" is proposed as more suitable in the rapidly changing environment of mobile networks since the signalled QoS information is not tied to a particular path. It also allows the flows to be rapidly established and, thus, is suitable for short lived and dynamic flows. INSIGNIA aims to minimize signaling by reducing the number of parameters that are provided to the network. It assumes that real- time flows may tolerate some loss, but are very delay sensitive so that the only QoS information needed is the required minimum and maximum bandwidth. The INSIGNIA protocol operates at the network layer and assumes that link status sensing and access schemes are provided by lower layer entities. The usefulness of the scheme depends upon the MAC layers but this is undefined so that INSIGNIA can run over any MAC layer. The protocol requires that each router maintains per-flow state. The INSIGNIA system implicitly supports mobility. A near-minimal amount of information is exchanged with the network. To achieve this, INSIGNIA makes many assumptions about the nature of traffic that a source will send. This may also simplify admission control and buffer allocation. The system basically assumes that "real-time" will be defined as a maximum delay and the user can simply request real-time service for a particular quantity of traffic. After handover, data that was transmitted to the old base station can be forwarded to the new base station so that no data loss should occur. However, there is no way to differentiate between re-routed and new traffic so priority cannot be given to handover traffic, for example. Manner et al Expires April 2003 [Page 14] Internet-Draft Analysis of QoS Signaling October 2002 5.2. Mobile RSVP Mobile RSVP (MRSVP) [MRSVP] is an extension to standard RSVP. It is based on advance reservations, where neighboring access points keep resources reserved for mobile nodes moving to their coverage area. When a mobile node requests resources, the neighboring access points are checked too and a passive reservation is done around the mobile nodes current location. 5.3. BGRP Border Gateway Reservation Protocol (BGRP) [BGRP] is a signaling protocol for interdomain aggregated resource reservation for unicast traffic. BGRP builds a sink tree for each of the stub domains. Each sink tree aggregates bandwidth reservations from all data sources in the network. BGRP maintains these aggregated reservations using soft state and relies on Differentiated Services for data forwarding. BGRP scales in terms of message processing load, state storage and bandwidth. Since backbone routers only maintain the sink tree information, the total number of reservations at each router scales linearly with the number of Internet domains. 5.4. ST-II ST-II [RFC1819] is an experimental resource reservation protocol intended to provide end-to-end real-time guarantees over an internet. It allows applications to build multi-destination simplex data streams with a desired quality of service. ST-II consists of two protocols: ST for the data transport and SCMP, the Stream Control Message Protocol, for all control functions. ST is simple and contains only a single PDU format that is designed for fast and efficient data forwarding in order to achieve low communication delays. SCMP packets are transferred within ST packets. ST-II has no built-in soft states, thus requires that the network be responsible for correctness. It is sender-initiated, and the overhead for ST-II to handle group membership dynamics is higher than RSVP [MESZ94]. Manner et al Expires April 2003 [Page 15] Internet-Draft Analysis of QoS Signaling October 2002 5.5. The ITSUMO Framework The ITSUMO Framework [CCM+00] is an example of an architecture with a hierarchy of bandwidth brokers. The architecture is based on Differentiated Services: the traffic is aggregated and forwarded in backbone networks based on per-hop behaviors. In the architecture there is at least one global server and several local nodes in each Radio Access Network (RAN). The server is referred to as the QoS Global Server (QGS) and local nodes are referred to as QoS Local Nodes (QLN). The QLNs are ingress nodes of the DiffServ domain. They usually reside at the edge of a wired backbone network and a Layer 2 Radio Access Network. The QGS retains the global information of the domain and informs QLNs what to do when traffic comes in. The mobile node communicates its QoS requirements directly to the QGS through the use of SIP messages, for example. Once the mobile node has had such a request accepted, it is guaranteed within the Service Level Agreement, that the node can move in the domain and receive the required QoS. The QGS server has a near-to-complete picture of the state of the network at any time. This is achieved by regular polling of all QLNs. The QGS uses the received information to determine if a particular request can be supported. Once it has concluded that the request cab be fulfilled, it broadcasts the decision to all nodes likely to be affected by the mobile node. Mobility guarantees are made by notifying QLNs of mobile nodes likely to arrive into their cells. The Service Level Specification (SLS) is usually agreed by both the user and the service provider when the user signs up a service subscription. To change the SLS in wired network, the mobile has to contact the service provider. Once the negotiation is done, the mobile can utilize the new SLS. Once the negotiation between the mobile and the QGS is done, the QGS multicasts the decision to all QLNs in the same administration domain. Therefore, the mobile node can utilize the new SLS anywhere within the same administrative domain. Thus, dynamic SLS for mobile environment is achieved with a single negotiation in one administration domain. The ITSUMO approach offers classes of services mainly based on the combination of two parameters: latency and loss. For each parameter possible values are high, moderate, and low for latency and high, moderate, low, and none for the packet loss. The combination of the two parameters forms a spectrum with 12 classes of services. Furthermore, the ITSUMO architecture includes a set of mobility protocols. The Dynamic Registration and Configuration Protocol (DRCP) is similar than the Dynamic Host Configuration Protocol (DHCP) and supports host configuration and registration. The Host Mobility and Management Protocol (HMMP) provides dynamic address binding and personal mobility. Manner et al Expires April 2003 [Page 16] Internet-Draft Analysis of QoS Signaling October 2002 6. Summary - Gather the good ideas from the protocols as a basis for the future designs - Perhaps note that extensive features and simplicity do not go hand- in-hand: "if you want features, be prepared to pay for the cost". 7. Security Considerations There are no security issues in this document. Individual protocols include different levels of security issues and those are highlighted in the relevant sections. 8. Contributors This document is part of the work done in the NSIS Working Group. The draft was initially written by Jukka Manner and Xiaoming Fu. 9. Acknowledgement 10. References [RFC1819] L. Delgrossi and L. Berger, Editors, Internet Stream Protocol Version 2 (ST2) Protocol Specification - Version ST2+, RFC 1819, August 1995. [MESZ94] D. Mitzel, D. Estrin, S. Shenker, and L. Zhang, An Architectural Comparison of ST-II and RSVP, INFOCOM'94. [BEBH96] Braden, R., Estrin, D., Berson, S., Herzog, S. and D. Zappala, "The Design of the RSVP Protocol", ISI Final Technical Report, Jul 1996. [RSVP] Zhang, L., Deering, S., Estrin, D. and D. Zappala, "RSVP: A New Resource Reservation Protocol", IEEE Network, Volume 7, Pages 8-18, Sep 1993. [RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S. and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, Sep 1997. [RFC2207] L. Berger and T. O'Malley, RSVP Extensions for IPSEC Data Flows, RFC 2207, September 1997. [RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated Services", RFC 2210, September 1997. Manner et al Expires April 2003 [Page 17] Internet-Draft Analysis of QoS Signaling October 2002 [RFC2998] Bernet, Y., Yavatkar, R., Ford, P., Baker, F., Zhang, L., Speer, M., Braden, R. and B. Davie, "Integrated Services Operation over Diffserv Networks", RFC 2998, November 2000. [RFC2749] Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja, R. and A. Sastry, COPS usage for RSVP, RFC 2749, January 2000. [RFC2750] Herzog, S., RSVP Extensions for Policy Control, RFC 2750, January 2000. [RFC2751] Herzog, S., Signaled Preemption Priority Policy Element, RFC 2751, January 2000. [RFC2752] Yadav, S., et al., "Identity Representation for RSVP", RFC 2752, January 2000. [RFC2747] Baker, F., Lindell, B. and M. Talwar, RSVP Cryptographic Authentication, RFC 2747, January 2000. [RFC2380] Berger, L., RSVP over ATM Implementation Requirements, RFC 2380, August 1998. [RFC2814] Yavatkar, R., Hoffman, D., Bernet, Y., Baker, F. and M. Speer, SBM (Subnet Bandwidth Manager): A Protocol for Admission Control over IEEE 802-style Networks, RFC 2814, May 2000. [RFC2745] Terzis, A., Braden B., S. Vincent, and L. Zhang, RSVP Diagnostic Messages, RFC 2745, January 2000. [RFC2746] Terzis, A., Krawczyk, J., Wroclawski, J. and L. Zhang, RSVP Operation Over IP Tunnels, RFC 2746, January 2000. [RFC2961] Berger, L., Gan, D., Swallow, G., Pan, P. and F. Tommasi, RSVP Refresh Reduction Extensions, RFC 2961, April 2001. [RFC2996] Bernet, Y., Format of the RSVP DCLASS Object, RFC 2996, November 2000. [RFC2997] Bernet, Y., Smiht, A. and B. Davie, Specification of the Null Service Type, RFC 2997, November 2000. [RFC3175] F. Baker, C. Iturralde, F. Le Faucheur, B. Davie, Aggregation of RSVP for IPv4 and IPv6 Reservations, RFC 3175, September 2001 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V. and G. Swallow, Extensions to RSVP for LSP Tunnels, RFC 3209, December 2001. [RFC3270] F. Le Faucheur (ed), L. Wu, and et al, Multi-Protocol Label Switching (MPLS) Support of Differentiated Services, RFC 3270, May 2002. [RFC2362] Estrin, D., Farinacci, D., Helmy, A., Thaler, D., Manner et al Expires April 2003 [Page 18] Internet-Draft Analysis of QoS Signaling October 2002 Deering, S., Handley, M. and V. Jacobson, "Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification", RFC 2362, June, 1998. [Hame02] L-N. Hamer, et al, Session Authorization Policy Element, Internet Draft, October 2002. (draft-ietf-rap-rsvp-authsession-04.txt) [BEGD02] Bernet, Y., Elfassy, N., Gai, S. and D. Dutt, "RSVP Proxy", draft-ietf-rsvp-proxy-03 (work in progress), Mar 2002. [Meer02] H. de Meer, et al. "Analysis of Existing QoS Solutions". Internet Draft. (draft-demeer-nsis-analysis-02.txt) [Tsch02] Hannes Tschofenig, "RSVP Security Properties". Internet Draft, June 2002. (draft-tschofenig-rsvp-sec-properties-00.txt) [Fu02] Xiaoming Fu, et al, "Analysis on RSVP Regarding Multicast". Internet Draft, October 2002. (draft-fu-rsvp-multicast-analysis-01.txt) [Thom01] Michael Thomas, "Analysis of Mobile IP and RSVP Interactions". draft-thomas-seamoby-rsvp-analysis-00.txt (expired). Available from eg. (www.mtcc.com/standards/draft-thomas-seamoby-rsvp-analysis-00.txt) [RaNa98] B. Rajagopalan and R. Nair. "Multicast Routing with Resource Reservation". Journal of High Speed Networks, 7(2), pp. 113-139, July 1998. [FrJo02] Pierre Fransson and Andreas Jonsson, "The need for an alternative to IPv4-options", in RVK (RadioVetenskap och Kommunikation), Stockholm, Sweden, pp. 162-166, June 200. [MHS02] Yu-Ben Miao, Wen-Shyang Hwang, Ce-Kuen Shieh, "A transparent deployment method of RSVP-aware applications on UNIX". Computer Networks, 40 (2002), pp. 45-56. [FNS02] Gabor Feher, Krisztian Nemeth, Istvan Cselenyi, "Performance evaluation framework for IP resource reservation signalling". Performance Evaluation 48 (2002), pp. 131-156. [PaSc98] Ping Pan, Henning Schulzrinne, "YESSIR: A Simple Reservation Mechanism for the Internet". In the Proceedings of NOSSDAV, Cambridge, UK, July 1998. [PaSc00] P. Pan, and H. Schulzrinne, "Lightweight Resource Reservation Signaling: Design, Performance and Implementation", Bell Labs Technical Memorandum 10009669-03, July 2000. [KaSh01] Martin Karsten, Jens Schmitt, Ralf Steinmetz, "Implementation and Evaluation of the KOM RSVP Engine". IEEE Infocom 2001. Manner et al Expires April 2003 [Page 19] Internet-Draft Analysis of QoS Signaling October 2002 [Kars01] Martin Karsten, "Experimental Extensions to RSVP -- Remote Client and One-Pass Signalling". IWQoS 2001, Karlsruhe, Germany, June 2001. [LGZC00] S. Lee, A. Gahng-Seop, X. Zhang, A. Campbell,"INSIGNIA: An IP-Based Quality of Service Framework for Mobile Ad Hoc Networks". Journal of Parallel and Distributed Computing (Academic Press), Special issue on Wireless and Mobile Computing and Communications}, Vol. 60, Number 4, April, 2000, pp. 374-406. [CCM+00] Jyh-Cheng Chen, Armando Caro, Anthony McAuley, Shinichi Baba, Yoshihiro Ohba, Parameswaran Ramanathan,"A QoS Architecture for Future Wireless IP Networks". Proceedings of the Twelfth IASTED International Conference on Parallel and Distributed Computing and Systems (PDCS 2000), Las Vegas, NV, November, 2000. [FNM+99] G. Feher, K. Nemeth, M. Maliosz, I. Cselenyi, J. Bergkvist, D. Ahlard, T. Engborg, "Boomerang A Simple Protocol for Resource Reservation in IP Networks", IEEE RTAS, 1999. [MSK+02] J. Manner, T. Suihko, M. Kojo, M. Liljeberg, K. Raatikainen, "Localized RSVP". Internet Draft, May 2002. (draft-manner-lrsvp-00.txt) [BGRP] P. Pan, E, Hahne, and H. Schulzrinne, "BGRP: A Tree-Based Aggregation Protocol for Inter-domain Reservations", Journal of Communications and Networks, Vol. 2, No. 2, June 2000, pp. 157-167. [MRSVP] A. Talukdar, B. Badrinath, and A. Acharya, MRSVP: A Resource Reservation Protocol for an Integrated Services Network with Mobile Hosts, Wireless Networks, vol. 7, no. 1, pp. 5-19. 2001. 11. Author's Addresses Questions about this document may be directed to: Jukka Manner Department of Computer Science University of Helsinki P.O. Box 26 (Teollisuuskatu 23) FIN-00014 HELSINKI Finland Voice: +358-9-191-44210 Fax: +358-9-191-44441 E-Mail: jmanner@cs.helsinki.fi Xiaoming Fu Institute of Informatics Georg-August-University of Goettingen Lotzestrasse 16-18 Manner et al Expires April 2003 [Page 20] Internet-Draft Analysis of QoS Signaling October 2002 37083 Goettingen Germany Voice: +49-551-39-14411 Fax: +49-551-39-14403 E-Mail: fu@cs.uni-goettingen.de Manner et al Expires April 2003 [Page 21] Internet-Draft Analysis of QoS Signaling October 2002 Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Manner et al Expires April 2003 [Page 22]