SIGNET - Development of New, Extensible Internet Signaling Protocols
Mitarbeiter: Xiaoming Fu ,
Ingo Juchem ,
Niklas Steinleitner ,
Hannes Tschofenig
Projektpartner: Columbia University, Nokia Siemens, German Telecom, University of Cambridge, Technical University Braunschweig, University of Helsinki, Ericsson
This project develops communication protocols that can be used to provide various signaling services, such as Quality of Service resource reservation setup or firewall configuration in network nodes along the data path of end-to-end communications in IP-based networks.
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2009
End-to-End Versus Hop-by-Hop Soft State Refresh for Multi-hop Signaling Systems ,
Jianhua He, Xiaoming Fu and Zuoying Tang, 17th IEEE International Conference on Network Protocols (ICNP 2009), Princeton, New Jersey, USA,
IEEE, October 2009.
Zusammenfassung lesen
To ensure state synchronization of signalling operations, many signaling protocol designs choose to establish “soft” state that expires if it is not refreshed. The approaches of refreshing state in multi-hop signaling system can be classified as either end-to-end (E2E) or hop-by-hop (HbH). Although both state refresh approaches have been widely used in practical signaling protocols, the design tradeoffs between state synchronization and signaling cost have not yet been fully investigated. In this paper, we investigate this issue from the perspectives of state refresh and state removal. We propose simple but effective Markov chain models for both approaches and obtain closed-form solutions which depict the state refresh performance in terms of state
consistency and refresh message rate, as well as the state removal performance in terms of state removal delay. Simulations verify the analytical models. It is observed that the HbH approach yields much better state synchronization at the cost of higher signaling cost than the E2E approach. While the state refresh performance can be improved by increasing the values of state refresh and timeout timers, the state removal delay increases largely for both E2E and HbH approaches. The analysis here shed lights on the design of signaling protocols and the configuration of the timers to adapt to changing network conditions.
PDF [176.2 kB]
Method for carrying out a QoS-oriented handoff between a first and a second IP-based, especially mobile IPV6-based, communication path, between a mobile node (MN) and a correspondent node (CN) ,
Changpeng Fan, Andreas Festag, Xiaoming Fu , Cornelia Kapper, Holger Karl, Mirko Schramm, and Günter Schäfer (inventors), granted patent, No. EP20010953886,
July 2009.
Zusammenfassung lesen
The invention relates to a method for carrying out a QoS-oriented handoff between a first and a second IP-based, especially mobile IPv6-based, communication path, between a mobile node (MN) and a correspondent node (CN), the second communication path being part of a number of communication paths which can be accessed by the mobile node, with no, one, or a plurality of intermediate instances. The inventive method comprises at least the following steps: (a) a communication path is selected from the communication paths which can be accessed by the mobile node, as a second communication path; (b) a message (BU) is generated by the mobile node, said message containing at least one IP address which is associated with the mobile node on the basis of the selected communication path, and containing minimum quality of service requirements (QoS) in terms of the selected communication path; (c) the ability to meet at least the minimum quality of service requirements is controlled and optionally ensured by the individual intermediate instances through which the message passes successively, on the selected communication path and/or through the correspondent node. The message contains the minimum quality of service requirements for a communication from the mobile node to the correspondent node and/or vice versa. A handoff is automatically carried out between the first communication path and the second selected communication path, when at least the minimum quality of service requirements are met or the message is stopped. A notice is generated in an intermediate instance and/or in the correspondent node and is sent to the mobile node if the ability to meet the minimum quality of service requirements is not ensured.
End-to-End versus Hop-by-Hop State Refresh in Soft State Signaling Protocols ,
Jianhua He, Xiaoming Fu , Zuoyin Tang, and Hisiao-Hwa Chen, IEEE Communications Letters, 13(4): 268-270,
IEEE, April 2009.
Zusammenfassung lesen
The concept of soft state (i.e., the state that will expire unless been refreshed) has been widely used in the design of network signaling protocols. The approaches of refreshing state in multi-hop networks can be classified to end-to-end (E2E) and hop-by-hop (HbH) refreshes. In this article we propose an effective Markov chain based analytical model for both E2E and HbH refresh approaches. Simulations verify the analytical models, which can be used to study the impacts of link characteristics on the performance (e.g., state synchronization and message overhead), as a guide on configuration and optimization of soft state signaling protocols.
PDF [168.3 kB]
Overhead and Performance Study of the General Internet Signaling Transport (GIST) Protocol ,
Xiaoming Fu , Henning Schulzrinne, Hannes Tschofenig , Christian Dickmann , and Dieter Hogrefe, ACM/IEEE Transactions on Networking, 17(1): 158-171,
February 2009.
Zusammenfassung lesen
The General Internet Signaling Transport (GIST) protocol is currently being developed as the base protocol component in the IETF Next Steps In Signaling (NSIS) protocol stack to support a variety of signaling applications. We present our study on the protocol overhead and performance aspects of GIST. We quantify network-layer protocol overhead and observe the effects of enhanced modularity and security in GIST. We developed a first open source GIST implementation at the University of Goettingen, and study its performance in a Linux testbed. A GIST node serving 45,000 signaling sessions is found to consume average only 1.1 ms for processing a signaling message and 2.4 KB of memory for managing a session. Individual routines in the GIST code are instrumented to obtain a detailed profile of their contributions to the overall system processing. Important factors in determining performance, such as the number of sessions, state management, refresh frequency, timer management and signaling message size are further discussed. We investigate several mechanisms to improve GIST performance so that it is comparable to an RSVP implementation.
PDF [210.7 kB]
2008
Performance Study of the NSIS QoS-NSLP Protocol ,
Mayutan Arumaithurai , Xiaoming Fu , Bernd Schloer , and Hannes Tschofenig , The 51th Annual IEEE Global Telecommunications Conference (GLOBECOM 2008), Next Generation Networks, Protocols, and Services Symposium, New Orleans, LA, USA,
IEEE, December 2008.
Zusammenfassung lesen
This paper presents an evaluation of the Quality of Service Signalling Layer Protocol (QoS-NSLP) of the NSIS (Next Steps In Signalling) protocol suite. The QoS-NSLP in combination with the NSIS Transport Layer Protocol (NTLP) is proposed by the Internet Engineering Task Force (IETF) as an alternative to the Resource reSerVation Protocol (RSVP). We describe our implementations of the software architecture, both on a network simulator and on a Linux implementation. Both implementations are used in a complimentary manner to illustrate the performance of the QoS-NSLP protocol. The results show the performance of QoS-NSLP with respect to resource consumption, packet processing time, session set up time, refresh interval and protocol overhead. Furthermore, we analyse the protocol performance during route change scenarios.
PDF [328.7 kB]
2007
Implementation and Performance Evaluation of the IETF QoS NSLP Protocol ,
Bernd Schloer , Master's thesis, No. GAUG-ZFI-BM-2007-37, Center for Informatics, University of Goettingen, Germany,
ISSN 1612-6793, October 2007.
Zusammenfassung lesen
The main focus of this thesis is an open source implementation of the NSIS QoS NSLP with the support of signalling IntServ Controlled Load Service and its evaluation. The implementation was done in a research project at the University of Goettingen. Several software design features were introduced during the implementation work which yields in a stable and timely responsive application. The design features include a state machine, a traffic control interface and a timer library which together cover the whole functionality of the implementation.
PDF [1679.2 kB]
Method for carrying out a QoS-oriented handoff between a first and a second IP-based, especially mobile IPV6-based, communication path, between a mobile node (MN) and a correspondent node (CN) ,
Changpeng Fan, Andreas Festag, Xiaoming Fu , Cornelia Kapper, Holger Karl, Mirko Schramm, and Günter Schäfer (inventors), granted patent, No. AU2001276315,
August 2007.
Zusammenfassung lesen
The invention relates to a method for carrying out a QoS-oriented handoff between a first and a second IP-based, especially mobile IPv6-based, communication path, between a mobile node (MN) and a correspondent node (CN), the second communication path being part of a number of communication paths which can be accessed by the mobile node, with no, one, or a plurality of intermediate instances. The inventive method comprises at least the following steps: (a) a communication path is selected from the communication paths which can be accessed by the mobile node, as a second communication path; (b) a message (BU) is generated by the mobile node, said message containing at least one IP address which is associated with the mobile node on the basis of the selected communication path, and containing minimum quality of service requirements (QoS) in terms of the selected communication path; (c) the ability to meet at least the minimum quality of service requirements is controlled and optionally ensured by the individual intermediate instances through which the message passes successively, on the selected communication path and/or through the correspondent node. The message contains the minimum quality of service requirements for a communication from the mobile node to the correspondent node and/or vice versa. A handoff is automatically carried out between the first communication path and the second selected communication path, when at least the minimum quality of service requirements are met or the message is stopped. A notice is generated in an intermediate instance and/or in the correspondent node and is sent to the mobile node if the ability to meet the minimum quality of service requirements is not ensured.
2006
Beyond QoS Signaling: a Generic IP Signaling Framework ,
Xiaoming Fu , Hannes Tschofenig , and Dieter Hogrefe, Computer Networks, Volume 50, Issue 17, pages 3416-3433,
Elsevier, December 2006.
Zusammenfassung lesen
This paper describes the design principles and an introduction of a framework and protocols for generic IP signaling, namely the Cross-Application Signaling Protocol (CASP) and its signaling applications. While reusing certain features of the existing RSVP protocol, CASP overcomes its shortcomings and may be deployed as a replacement technology to provide simpler, mobility-supported, more extensible and more secure signaling services in IP based networks. This paper discusses challenges of todays IP signaling protocols and addresses fundamentals and key aspects of CASP and its current signaling applications. In addition, a comparison with previous signaling protocol proposals and an outlook of future work in this area are also given.
PDF [602.3 kB]
From Resource Reservation to Extensible IP Signaling ,
Xiaoming Fu , Habilitation Thesis, Mathematische Fakultaet, Universitaet Goettingen, Goettingen, Germany, 146 pages,
October 2006.
Securing the Next Steps in Signalling (NSIS) Protocol Suite ,
Hannes Tschofenig , and Xiaoming Fu , International Journal of Internet Protocol Technology, Volume 1, No. 4, pages 271-282,
InderScience Publishers, ISSN 1743-8209, August 2006.
Zusammenfassung lesen
The Next Steps In Signalling (NSIS) protocol suite represents an extensible framework for enabling various signalling applications over IP-based networks. The framework consists of two layers that need different types of security protection; the lower layer mainly deals with the discovery of adjacent peers and establishment of channel security to protect the delivery of signalling messages between two peers, while the upper layer provides the signalling application specific functionalities. Different security properties are required at the two layers with stronger authorisation functionality at the signalling application layer. In this paper we examine how various security vulnerabilities can be utilised by an adversary, including eavesdropping, Man-In-The-Middle (MITM) attacks, fraud and Denial of Service (DoS) attacks. Moreover, we describe how to protect against a number of selected security threats and highlight some security challenges that require further research.
PDF [431.5 kB]
Implementation and Performance Study of a New NAT/Firewall Signaling Protocol ,
Niklas Steinleitner , Henning Peters , Xiaoming Fu , and Hannes Tschofenig , in Proceedings of the 26th International Conference on Distributed Computing Systems-Workshops (ICDCSW 2006), the 5th International Workshop on Assurance in Distributed Systems and Networks (ADSN2006), Lisboa, Portugal,
IEEE Computer Society, ISBN 0-7695-2541-5, July 2006.
Zusammenfassung lesen
The NAT/Firewall NSIS Signaling Layer Protocol (NAT/FW NSLP) is a path-coupled signaling protocol for explicit Network Address Translator and firewall configuration within an extensible IP signaling framework currently being developed by the IETF Next Steps in Signaling (NSIS) working group. This new protocol allows end hosts to signal along a path to configure NATs and firewalls according to the data flow needs. In this paper we present a first open source implementation and performance evaluation of the NAT/FW NSLP protocol. The implementation utilizes a generic state machine template and can automatically generate source code for message handling classes. The performance study shows that our implementation scales well and is able to support firewall signaling for up to tens of thousands of flows in parallel even in a low-end PC testbed environment. The overall performance bottleneck is found to lie in the utilized firewall implementation, not depending on the NAT/FW NSLP implementation.
PDF [394.6 kB]
Modelling Soft-State Protocols with SDL ,
Xiaoming Fu , IEE Proceedings Communications,
ISSN 1350-2425, Volume 153, Issue 3, pages 365-375, June 2006.
Zusammenfassung lesen
The notion of soft state has been introduced in packet-switched networks to achieve particular services for end-to-end communications, such as quality-of-service provisioning and configuration of stateful packet filters. Protocols built upon soft state principles were believed to be simple, however in practice they are far more complex. An important issue with such protocols is to ensure their operations to be error-free and deadlock-free. In the paper the use of formal techniques is proposed, specifically, Specification and Description Language (SDL) and Message Sequence Charts (MSCs), for modelling, analysis and validation of soft-state protocols. Based on a general state management system that identifies their most representative behaviour, an extensive study on modelling and validating soft-state protocols with SDL/MSCs is presented, and it is shown that design flaws and ambiguity introduced in informally specified, textual protocols can be avoided if a protocol is formally modelled.
PDF [341.0 kB]
Overhead and Performance Study of the General Internet Signaling Transport (GIST) Protocol ,
Xiaoming Fu , Henning Schulzrinne, Hannes Tschofenig , Christian Dickmann , and Dieter Hogrefe, IEEE INFOCOM 2006, Bacelona, Spain,
IEEE, April 2006.
Zusammenfassung lesen
The General Internet Signaling Transport (GIST) protocol is currently being developed as the base protocol component in the IETF Next Steps In Signaling (NSIS) protocol stack to support a variety of signaling applications. In this paper we present our study on the protocol overhead and performance aspects of GIST. We quantify network-layer protocol overhead and observe the effects of enhanced modularity and security in GIST. We developed a first open source GIST implementation at the University of Göttingen, and study its performance in a Linux testbed. A GIST node serving 45,000 signaling sessions is found to consume small amounts of CPU and memory (on average 1.1ms for processing a signaling message and 2.4KB memory for a session). Individual routines in the GIST code are instrumented to obtain a detailed profile of their contributions to the overall system processing. Important factors in determining performance, such as the number of sessions, state management, refresh frequency, timer management and signaling message size are further discussed. We investigate several mechanisms to improve GIST performance so as to be comparable with an RSVP implementation.
PDF [181.9 kB]
Analysis of NAT Approaches and Explicit Signaling for NAT Traversal ,
Henning Peters , Bachelor's thesis, No. ZFI-BM-2006-09, Zentrum fuer Informatik, Universitaet Goettingen,
ISSN 1612-6793, March 2006.
Zusammenfassung lesen
Network Address Translation (NAT) provides a solution for IPv4 address depletion and Internet scalability problems at large. NAT has since been unexpectedly popular, and it is in wide use today, especially in home and small office environments. Unfortunately, it has major drawbacks, most fundamental is the maintenance of states inside the network, challenging the Internets end-to-end principle.
This thesis analyzes these very promising NAT approaches, and tries to compare the approaches with each other. Furthermore, an applicability statement for implicit and explicit NAT configuration is given and an implementation of NAT/Firewall NSLP proves the feasibility of an yet uncommon explicit signaling approach.
PDF [430.0 kB]
Principles and Experiments of Explicit Delay Control ,
Xiaoyuan Gu, Dirk Markwardt, Lars Wolf, and Xiaoming Fu , Proceedings of IEEE Consumer Communications and Networking Conference (CCNC'06), Las Vegas, USA,
IEEE, January 2006.
Zusammenfassung lesen
Real-time interactive multimedia applications are highly delay-sensitive, and packets that are out of delay boundaries are usually obsolete. However the current Internet Protocol lacks a way to control the lifetime of the packets explicitly. We propose a packet lifetime control mechanism called Explicit Delay Control (EDC) that embeds a Maximum Tolerable Delay (MTD) field in an IPv4 option. At each network node, the MTD is deducted by the singlehop delay. Packets that expire their lifetime are discarded and non-congestion related delay losses are signaled to the sender to reduce inaccuracy in delay estimations and to adapt to path changes. We implemented EDC in the Linux kernel. Our evaluation has shown that EDC is an effective scheme to ensure the legality of the packets, reduce the waste of bandwidth and processing time in the networks, and alleviate congestions.
PDF [207.6 kB]
2005
Implementation and Performance Testing of the NAT/FW NSIS Signaling Layer Protocol ,
Niklas Steinleitner , Master's thesis No. ZFI-BM-2005-41, Center for Informatics, University of Goettingen, Germany,
ISSN 1612-6793, December 2005.
Zusammenfassung lesen
This thesis describes the first implementation and performance testing of the path-coupled signaling protocol for Network Address Translator (NAT) and firewall configuration within an extensible IP signaling framework developed by the IETF Next Steps in Signaling (NSIS) working group, called the NAT/FW NSIS Signaling Layer Protocol (NAT/FW NSLP). This new protocol allows hosts to signal along a data path to configure NATs and firewalls according to the data flow needs.
In comparison with prior works on firewall signaling, one major contribution of this thesis is that it presents a detailed performance study of the NAT/FW NSLP protocol through an experimental testbed. The performance results show that implementation can support firewall signaling for up to tens of thousands of flows in parallel, and scale well. Besides the limitation due to the low-end PC hardware, the overall performance bottleneck is found to lie in the utilized firewall implementation, not depending on the NAT/FW NSLP implementation.
PDF [4063.9 kB]
A Quality-of-Service Resource Allocation Client for CASP ,
Henning Schulzrinne, Hannes Tschofenig , Xiaoming Fu , and Jochen Eisl, Technical Report No. TB-IFI-2005-07, Institute of Computer Science, University of Goettingen, Germany,
ISSN 1611-1044, November 2005.
Zusammenfassung lesen
Signaling resource reservations is one of the possible applications of the Cross-Application Signaling Protocol (CASP). This document describes a client protocol that supports per-flow resource reservationin both sender- and receiver-directed modes operation.
PDF [99.8 kB]
Security Implications of the Session Identifier ,
Hannes Tschofenig , Henning Schulzrinne, Robert Hancock, Andrew McDonald, and Xiaoming Fu , Technical Report No. TB-IFI-2005-08, Institute of Computer Science, University of Goettingen, Germany,
ISSN 1611-1044, November 2005.
Zusammenfassung lesen
As one result of the analysis activities in the NSIS group it was realized that mobility and the ability to change the flow identifier causes problems with existing QoS reservations. To be able to associate a signaling message with existing state an identifier other than the flow identifier had to be used. Such an abstraction is achieved with the session identifier which allows identification of established state independently of the flow characteristics.
Although the introduction of a session identifier sounds simple and beneficial, it introduces a problem which is subsequently referred to as the session ownership problem.
This document describes the session ownership problem, the implications for an NSIS protocol and summarizes already discussed solutions.
PDF [79.7 kB]
NSIS: A New Extensible IP Signaling Protocol Suite ,
Xiaoming Fu , Henning Schulzrinne, Attila Bader, Dieter Hogrefe, Cornelia Kappler, Georgios Karagiannis, Hannes Tschofenig , and Sven Van den Bosch, IEEE Communications Magazine, Internet Technology Series, 43(10): 133-141,
IEEE, October 2005.
Zusammenfassung lesen
In the last few years, a number of applications have emerged that can benefit from network-layer signaling, i.e., the installation, maintenance and removal of control state in network elements. These applications include path-coupled and path-decoupled quality of service (QoS) management and resource allocation, as well as network debugging, NAT and firewall control. These applications call for an extensible and securable signaling protocol. This paper discusses some of the recent standardization efforts in the IETF for a new extensible IP signaling protocol suite (NSIS). We describe the design of the NSIS protocol suite, and compare them with RSVP, the current Internet QoS signaling protocol.
PDF [159.9 kB]
An Implementation and Evaluation of the General Internet Signaling Transport Protocol ,
Christian Dickmann , Bachelor's thesis, No. ZFI-BM-2005-26, Zentrum fuer Informatik, Universitaet Goettignen,
ISSN 1612-6793, September 2005.
Zusammenfassung lesen
The General Internet Signaling Transport (GIST) Protocol is currently being developed by the IETF Next Steps in Signaling (NSIS) working group. It is the base protocol supporting a variety of signaling applications to be run on top of it. This thesis targets at validating the GIST specification as well as examining the design of an implementation. Therefore, I discuss the major design aspects of the GIST implementation that we developed at the University of Goettingen and evaluate it with respect to CPU and resource utilization.
The performance experiments show that the implementation performs reasonable even under heavy load. In general the implementation shows that the specification is very mature and that the main features work very well.
PDF [729.8 kB]
RSVP Standards Today and the Path Towards a Generic Messenger ,
Xiaoming Fu , and Jukka Manner, In: H. de Meer and N. Bhatti (eds.), Proceedings of the 13th International Workshop on Quality of Service (IWQoS 2005), Passau, Germany, Lecture Notes in Computer Science, Volume 3552, pages 385-387,
Springer Verlag, ISBN 3-540-26294-6, June 2005.
Zusammenfassung lesen
RSVP is a very well-known protocol to support resource reservations in IP-based networks. This paper provides a preliminary inventory of RSVP standards and discusses the path towards a generic messenger for Internet signaling.
PDF [62.4 kB]
Modeling Route Change in Soft State Signaling Protocols Using SDL: a Case of RSVP ,
Constantin Werner, Xiaoming Fu , and Dieter Hogrefe, in A. Prinz, R. Reed and J. Reed (eds.), Proceedings of the 12th SDL Forum (SDL 2005), Grimstad, Norway, Lecture Notes in Computer Science, Volume 3530, pages 174-186,
Springer Verlag, ISBN 3-540-26612-7, June 2005.
Zusammenfassung lesen
Soft state signaling protocols install and maintain states in network nodes, expiring without receiving refreshes. These states require proper reparation when the flow path changes, especially in case of link or node failures. As the specifications usually do not describe in detail how to handle these failures, we present insights by developing SDL models for RSVP on this issue.
PDF [269.3 kB]
Modeling Soft State Protocols with SDL ,
Xiaoming Fu , and Dieter Hogrefe, In: R. Boutaba et al. (Eds.), Proceedings of the 4th IFIP International Conference on Networking (Networking 2005), Waterloo, Canada, Lecture Notes in Computer Science, Volume 3462, pp. 289-302,
Springer Verlag, ISBN 3-540-25809-4, May 2005.
Zusammenfassung lesen
Soft state provides new services to packet-switching networks by introducing a type of state in the network nodes which is refreshed by periodical messages and otherwise expires. The operations of soft state protocols, which are being designed with ever greater complexity, need to be error-free and deadlock-free to avoid misusing network resources. Thus, verification, formal analysis and validation of these protocols become a vital task. In this paper we utilize formal techniques, specifically Specification and Description Language (SDL) and Message Sequence Charts (MSCs), for modeling, analysis and validation of various soft state protocols. We propose a general architecture for state management systems and find employing these techniques can help identify and correct possible design errors, which may be caused by informal specifications.
PDF [162.9 kB]
Analysis of Existing Quality-of-Service Signaling Protocols ,
Jukka Manner, and Xiaoming Fu , Request for Comment (RFC) 4094,
Internet Engineering Task Force, May 2005.
Zusammenfassung lesen
This document reviews some of the existing Quality of Service (QoS) signaling protocols for an IP network. The goal here is to learn from them and to avoid common misconceptions. Further, we need to avoid mistakes during the design and implementation of any new protocol in this area.
PDF [68.0 kB]
2004
Implementation and Evaluation of the Cross-Application Signaling Protocol (CASP) ,
Xiaoming Fu , Dieter Hogrefe, and Sebastian Willert , Proceedings of the 12th IEEE International Conference on Network Protocols (ICNP 2004), Berlin, Germany, pp. 61-71,
IEEE Computer Society Press, ISBN 0-7695-2161-4, October 2004.
Zusammenfassung lesen
In this paper, we describe implementation aspects and performance results of a novel general signaling protocol for the Internet, the Cross-Application Signaling Protocol (CASP). There has been much debate on the applicability of RSVP as a general signaling protocol for the Internet, particularly with respect to its modularity, complexity, security and mobility support. Based on a layered architecture, the CASP design intends to address these challenges, which, unlike RSVP, provides a simpler mechanism for reliability and security by re-using existing protocols for transporting signaling messages. In addition, it supports a wide range of signaling applications. While this concept is considered to be advantageous over RSVP signaling, the actual mechanisms and behaviors of the CASP implementation have not yet been explored. Our study attempts to shed light on this issue by presenting a first public CASP implementation and preliminary examination of its properties. Performance results show and analyze the round trip times and their variances of signaling messages upon different number of signaling requests and different congestion situations in the experimental setup. The memory required for a large number of signaling sessions and the CPU consumption for each routine from profiling the implementation are low. Although further work is necessary, critical design choices in CASP have been proven useful and practically feasible.
PDF [111.3 kB]
Modeling Soft State Protocols with SDL ,
Xiaoming Fu , and Dieter Hogrefe, Technical Report No. IFI-TB-2004-02, Institute of Computer Science, University of Göttingen, Germany,
ISSN 1611-1044, August 2004.
Zusammenfassung lesen
Soft state enables new services to packet-switching networks by introducing a type of state in the network nodes which is refreshed by periodical messages otherwise expire. System designers build protocols that implement soft state concepts based on intuition or on high-level explanations believe that the design is "better" than hard state and soft state implementations should be robust, reliable and interoperable. As states in the network nodes are critical for both applications the and network infrastructure, the operations of soft state protocols, which tend to be designed more and more complex, need to be error-free and deadlock-free. Thus, verification, formal analysis and validation of these protocols become a vital task. In this paper we utilize formal techniques, specifically, Specification and Description Language (SDL) and Message Sequence Chart (MSC), for modeling, analysis and validation of general soft state protocols. We propose a general architecture of state management systems and find several points through the SDL/MSC modeling which may enrich the design, modeling and evaluation of real soft state protocols: 1) modeling these protocols using these techniques is feasible, 2) it can be possible to use these techniques to identify possible design errors and deadlocks/livelocks, which may be caused by imprecise informal specifications of these protocols.
PDF [112.1 kB]
Implementation and Evaluation of the Cross-Application Signaling Protocol (CASP) ,
Xiaoming Fu , Dieter Hogrefe, and Sebastian Willert , Technical Report No. IFI-TB-2004-001, Institute of Computer Science, University of Göttingen, Germany,
ISSN 1611-1044, April 2004.
Zusammenfassung lesen
In this report, we describe implementation aspects and performance results of a novel general signaling protocol for the Internet, the Cross-Application Signaling Protocol CASP). Much debate exists about the applicability of RSVP as a general signaling protocol in the Internet, particularly for its modularity, complexity, security and mobility support. Based on a layered architecture, the CASP design intends to address these challenges and unlike RSVP, it provides a simpler mechanism for reliability and security by re-using existing protocols for transporting signaling messages, and supports a wide range of signaling applications. While this concept is considered to be advantageous over RSVP signaling, the actual mechanisms and behaviors of the CASP implementation have not yet been explored. With our work, despite being still far from a final judgment, we try to shed light on this issue by presenting a first public CASP implementation and a preliminary study about its properties. Performance results show that even under heavy signaling loads, the round trip time of signaling messages is acceptable (appr. 5ms in serving more than 1000 simultaneous signaling client applications in the initiator each at a random refresh interval between 3s and 15s in our experiments), and the memory and CPU consumption of the implementation are low. Although further work will be necessary, critical design choices in CASP have been proved to be feasible.
PDF [416.3 kB]
A Prototype Implementation and Experimental Test of the Messaging Layer of CASP: a General-Purpose Internet Signaling Protocol ,
Sebastian Willert , Bachelor's thesis, No. ZFI-BM-2004-01, Zentrum fuer Informatik, Universitaet Goettignen,
ISSN 1612-6793, February 2004.
Zusammenfassung lesen
Signaling has become necessary for allowing IP-based networks to manage states in network nodes. However, existing protocols cannot deliver desired signaling services needed for large-scale deployment. The Cross-Application Signaling Protocol (CASP), a general-purpose signaling protocol, introduces a new approach to overcome the limitations of these protocols. This thesis reports a prototype implementation of the CASP transport layer protocol using TCP as the underlying transport protocol, and studies the feasibility of the modular design. The behavior of this implementation has been analyzed through an experimental testbed. Performance results show that the memory and CPU consumption of the implementation are low even under heavy signaling loads; the round trip time of signaling messages is also acceptable. Although further work will be necessary, critical design choices in CASP have been proved to be feasible.
PDF [719.9 kB]
Design and Implementation of a Scout Daemon for CASP ,
Fabian Meyer , Bachelor's thesis, No. ZFI-BM-2004-02, Zentrum fuer Informatik, Universitaet Goettignen, ISSN 1612-6793,
February 2004.
Zusammenfassung lesen
The CASP protocol is a general signaling protocol working on top of existing transport protocols such as TCP, UDP, SCTP or raw IP. It provides a framework for applications that need signaling. Applications include first of all QoS.
This thesis describes the design, implementation and testing of a scout daemon for CASP. The task of this daemon is to provide the main CASP daemon with a service, that can effectively discover the next CASP-aware hop on the path to a given destination. The experimental results show that the scout protocol implementation is stable, feasible and fast.
PDF [368.9 kB]
2003
Development of QoS Signaling Protocols in the Internet ,
Xiaoming Fu , Proceedings of the 28th Annual IEEE Conferfence on Local Computer Networks (LCN 2003), Bonn/Königswinter, Germany, pp. 636-637, Workshop on High-Speed Local Networks,
IEEE Computer Society Press, ISBN 0-7695-2037-5, October 2003.
Zusammenfassung lesen
QoS signaling protocol is one of the key components in Internet QoS architectures to establish, maintain, and remove reservation states in network nodes. This paper gives an overview of the recent efforts underway on next steps in QoS signaling protocols, namely RSVP extensions with mobility support, QoS-conditionalized handoff protocol, the layered architecture RSVP Lite and the Cross-Application Signaling Protocol (CASP). These efforts address main issues with existing approaches differently : modularity, complexity and mobility support, with a focus on protocol behaviors based on different design principles. The paper also provides pointers to standards effort towards general Internet signaling and other service-specific signaling protocols.
PDF [39.6 kB]
Mobility Support for Next-Generation Internet Signaling Protocols ,
Xiaoming Fu , Henning Schulzrinne, and Hannes Tschofenig , Proceedings of the IEEE 58th Vehicular Technology Conference (VTC 2003-Fall), Orlando, Florida, USA, pp. 1979-1983, Symposium on IP Mobility,
IEEE, ISBN 0-7803-7954-3, October 2003.
Zusammenfassung lesen
Internet signaling protocols establish, maintain and remove state along the data path. Next-generation signaling protocols design must meet the scaling requirements imposed by the various tasks of the Internet signaling applications, such as resource reservation and middlebox configuration, and to meet the demand for general functionality in signaling protocols, including strong security, reliability, congestion control, support for various signaling purposes and message sizes, and efficient support for mobility. This paper presents a generic signaling architecture, the Cross-Application Signaling Protocol (CASP) and describes how it supports efficient and secure signaling in IP mobility scenarios. In this approach, the signaling functionality is splitted into two layers: a generic messaging layer which provides the generic functionality for message delivery, and a client layer consisting of a next-hop discovery client and any number of client protocols which perform the actual signaling tasks. The essential mechanisms required to support mobility are: (1) a session identifier uniquely selected by the initiator and effective discovery of the cross-over node; (2) a branch identifier incrementally assigned for the new branch and efficient release of state in the abandoned branch; (3) ensuring discovery messages are delivered exactly following the path that mobile IP packets are encapsulated; (4) effective hop-by-hop authentication and reauthorization provided by the messaging layer, non hop-by-hop security for signaling clients and denial-of-service protection in the discovery client.
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CASP - Cross-Application Signaling Protocol ,
Henning Schulzrinne, Hannes Tschofenig , Xiaoming Fu , and Andrew McDonald, Technische Berichte des Instituts für Informatik an der Georg-August-Universität Göttingen,
Institut für Informatik, Georg-August-Universität Göttingen, Germany, ISSN 1611-1044, IFI-TB-2003-01, (equivalent to the Internet draft), March 2003.
Zusammenfassung lesen
CASP is a modular potocol for establishing network control state along a data path between two nodes communicating on the Internet.
The signalling problem addressed by CASP is the same as the overall problem being addressed by the NSIS activities.
The CASP framework is defined as a modular protocol, which includes a general purpose messaging layer (M-layer), which supports a number of client layers for particular ignalling applications (e.g. QoS, MIDCOM). In addition there is distinct, special purpose client component for next-peer discovery.
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Towards RSVP Lite: Light-weight RSVP for Generic Signaling ,
Xiaoming Fu , and Cornelia Kappler, Proceedings of the 17th International Conferfence on Advanced Information Networking and Applications, Xi'an, China, pp. 619-622,
IEEE Computer Society Press, ISBN 0-7695-1906-7, March 2003.
Zusammenfassung lesen
RSVP is a reservation setup protocol designed specifically to support QoS signaling in the Internet. However, RSVP end-to-end signaled QoS for the Internet has not become a reality. Moreover, there are many other applications demanding different signaling services. This paper analyses the features of RSVP version 1 we believe to be essential, and its complexity due to QoS-oriented design and multicast support as an indispensable component in a signaling protocol, deriving the design principles to be covered in a more generic signaling protocol. Based on this analysis, we present a light-weight version of RSVP, RSVP Lite, which clearly separates the signaled data from signaling messages and removes the multicast capability from the mandatory components of RSVP. RSVP Lite is intended to be applicable to a wide range of networking environments, while providing the flexibility to serve for generic signaling purposes and incremental deployment in the Internet.
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Design of CASP - a Technology Independent Lightweight Signaling Protocol ,
Henning Schulzrinne, Xiaoming Fu , Cornel Pampu, and Cornelia Kappler, Proceedings of the 1st International Workshop on Inter-domain Performance and Simulation (IPS 2003), Salzburg, Austria,
February 2003.
Zusammenfassung lesen
Existing signaling solutions are insufficient in terms of inter-domain and out-of-path signaling, mobility support and inter-working with policy and security mechanisms. The paper presents the Cross-Application Signaling Protocol (CASP) which is a general-purpose protocol for managing state information in network devices. This technology independent signaling protocol can be used for inter- and intra-domain QoS signaling, the configuration of middleboxes, for collecting measurement data and any other application where state management is required. It relies on existing transport protocols and consists of a messaging layer and a client layer. The messaging layer is application independent and is responsible for routing, session establishment and feature negotiation. In contrast to this application independent component of CASP, the client layer is the application-dependent part. As an example for a client the paper describes the QoS Resource Allocation Client for CASP and discusses requirements for extending CASP to include interdomain signaling. The discovery of next peers along the data path is handled by the Scout protocol, which is a specialized client protocol. Some of the basic mechanisms are derived from existing protocols. This way the design of this protocol relies on the experiences made in this area and is therefore one of the promising protocol candidates for the IETF NSIS WG.
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2002
Analysis on RSVP Regarding Multicast ,
Xiaoming Fu , Cornelia Kappler, and Hannes Tschofenig , Technische Berichte des Instituts für Informatik an der Georg-August-Universität Göttingen,
Institut für Informatik, Georg-August-Universität Göttingen, Germany, ISSN 1611-1044, IFI-TB-2002-001, October 2002.
Zusammenfassung lesen
RSVP version 1 has been designed for optimum support multicast. However, in reality multicast is being used much less frequently than anticipated. Still, even for unicast (one sender, one receiver) full-fledged multicast-enabled RSVP signaling must be used. As pointed out in the NSIS requirement draft, multicast would not be necessarily required for an NSIS signaling protocol. This draft analyses ingredients of RSVP Version 1 which are affected by multicast, and derives how these ingredients may look like if multicast is not supported in the generic RSVP signaling protocol and adapt related functionalities accordingly - we call the resulting feature set "RSVP Lite", a potentially more light-weight version of RSVP.
PDF [335.7 kB]
