Active networks and applications C. PHAM RESAM laboratory December 6th, 2000 Outline Introduction Nowadays network technologies Active networking Application: Active Reliable Multicast Conclusions 2 Outline Introduction Nowadays network technologies Active networking Application: Active Reliable Multicast Conclusions 3 The need for communication 4 The way people are communicating… Internet 5 Internet milestone Something really fast ATM, QoS, RVSP, DiffServ, IPv6, MPLS… 2000 Internet 2, NG Internet as you know it 1990 1983 1974 ?? 1995 ANSNET from MERIT, MCI, IBM ARPANET has 200 transit nodes TCP/IP for internetworking 1969 ARPANET was born with 4 transit nodes 1968 First transit node by BBN on DDP 316 1960 DoD project for a reliable, flexible network 6 User perspective of the Internet from UREC, http://www.urec.fr 7 What it is in reality… from UREC, http://www.urec.fr 8 Outline Introduction Nowadays network technologies Active networking Application: Active Reliable Multicast Conclusions 9 Links: the basic element for networking Backbone links optical fibers 40 to 60 GBits/s with DWDM techniques End-user access V.90 56KBits/s modem on twisted pair 512Kbits/s to 2MBits/s with xDSL modem 1Mbits/s to 10Mbits/s Cable-modem 64Kbits/s to 1930KBits/s ISDN access 9.6KBits/s (GSM) to 2MBits/s (UMTS) 10 Routers: key elements of internetworking Routers run routing protocols and build routing table, receive data packets and perform relaying, may have to consider Quality of Service constraints for scheduling packets, are highly optimized for packet forwarding functions. 11 General architecture of an IP router IP input processing IP output processing IP packet IP packet Filter Action Routing agent Forwarding table Packet scheduler IP output processing IP packet IP packet Packet scheduler receives input packets, sends packets to output buffers, transmits packets (with QoS?). 12 Desires put on the general Internet High-bandwidth Ubiquity of the network access (wireless, RTC, xDSL, mobile…) for remaining connected everywhere Quality of Service for bandwidth-consuming applications for high-quality multimedia receptio Dynamicity, adaptability to take into account recent technologies 13 Challenges for the Internet high-speed www video-conferencing video-on-demand interactive TV programs tele-medecine high-performance computing, grids virtual reality, immersion systems distributed interactive simulations remote archival systems 14 The reality…(1) High-bandwidth accesses are not available for everybody high-bandwidth is achievable in the core network with optical fibers and DWDM techniques but, most end-users have an access ranging from 56Kbits/s to 2Mbits/s and, it will be the case for many years! 15 The reality…(2) An ubiquitous network access generally implies heterogeneity and asymmetric performances, how to take into account this heterogeneity? The heterogeneity of bandwidth makes QoS a difficult quest on an end-to-end basis, seems that QoS is the networking forever Graal… 16 The reality…(3) New technologies require years to be deployed need for standardization IPv6, MPLS new services and protocols are costly to deploy many proprietary implementations, no interoperability of services and new technologies DiffServ, TagSwitching, LabelSwitching… 17 Towards a better Internet… Interoperability of systems Rapid deployment of new services, accelerating infrastructure innovation Take into account the heterogeneity of needs and network accesses Customization of services, applicationoriented processing features 18 Towards the concept of… Introduction Nowadays network technologies Active networking Application: Active Reliable Multicast Conclusions 19 What is active networks? Programmable nodes/routers Customized computations on packets Standardized execution environment and programming interface No killer applications, only a different way to offer high-value services, in an elegant manner However, adds extra processing cost 20 Motivations behind Active Networking From the user perspective From the operator perspective applications can specify, implement, and deploy (on-the-fly) customized services and protocols reduce the latency/cost for new services deployment/management From the network perspective globally better performances by reducing the amount of traffic 21 Active networks implementations Discrete approach (operator's approach) Adds dynamic deployment features in nodes/routers New services can be downloaded into router's kernel Integrated approach Adds executable code to data packets Capsule = data + code Granularity set to the packets 22 The discrete approach Separates the injection of programs from the processing of packets A1 A2 active code A1 active code A2 Data Data 23 The integrated approach User packets carry code to be applied on the data part of the packet data code data data data data code High flexibility to define new services 24 An active router AL packet IP input processing some layer for executing code. Let's call it Active Layer IP output processing IP packet IP packet Filter Action Routing agent Forwarding table Packet scheduler IP output processing IP packet IP packet Packet scheduler 25 Interoperability with legacy routers APPLI APPLI AL AL TCP/UDP TCP/UDP IP IP traditional IP routing IP IP AL AL TCP/UDP TCP/UDP IP IP 26 Some open problems… Security and integrity Performances how to be sure that user code are safe? how to add active computation without weeping out performances? Standardization of programming interface How to bill the CPU time? 27 Some active network applications Customization of services Filtering Web-caching, on-the-fly compression/encryption Auction, Distributed Interactive Simulations Firewall Congestion control QoS Network management Reliable multicast Middleware collective operation 28 Where to put active components? In the core network? routers already have to process millions of packets per second gigabit rates make additional processing difficult without a dramatic slow down At the edge? to efficiently handle heterogeneity of user accesses to provide QoS, implement intelligent congestion avoidance mechanisms… 29 PSTN ISDN xDSL GSM, UMTS 10Mbits/s core network Gbits/s Server 100Mbits/s wireless LAN 1Mbits/s, 10MBits/s visio-conferencing Outline Introduction Nowadays network technologies Active networking Application: Active Reliable Multicast Conclusions 31 Unicast Problem Sender Sending same data to many receivers via unicast is inefficient R Example Popular WWW sites become serious bottlenecks from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee 32 Multicast Efficient one to many data distribution Sender R from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee 33 Multicast History Ethernet Long history of usage on shared medium networks Data distribution Resource discovery: ARP, Bootp, DHCP Broadcast (software filtered) Multicast (hardware filtered) Multiple LAN multicast protocols DECnet, AppleTalk, IP from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee 34 IP Multicast Introduction Efficient one to many data distribution Location independent addressing Tree style data distribution Packets traverse network links only once IP address per multicast group Receiver oriented service model Applications can join and leave multicast groups Senders do not know who is listening Similar to television model Contrasts with telephone network, ATM from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee 35 IP Multicast Service All senders send at the same time to the same group Receivers subscribe to any group Routers find receivers Unreliable or reliable delivery Reserved IP addresses 224.0.0.0 to 239.255.255.255 reserved for multicast Static addresses for popular services (e.g. SAP) from Gordon Chafee, http://bmrc.berkeley.edu/people/chaffee 36 Example: video-conferencing from UREC, http://www.urec.fr 37 video-conferencing (2) 224.2.0.1 Multicast address group 224.2.0.1 from UREC, http://www.urec.fr 38 Multicast difficulties At the routing level management of the group address (IGMP) dynamic nature of the group membership construction of the multicast tree (pruning…) multicast packet forwarding At the transport level reliability, loss recovery strategies flow control congestion avoidance 39 Reliable multicast What is the problem of loss recovery? feedback (ACK or NACK) implosion replies/repairs duplications adaptability to dynamic membership changes Design goals reduces recovery latencies reduces the feedback traffic improves recovery isolation 40 Solutions Traditional end-to-end retransmission schemes scoped retransmission with the TTL fields receiver-based local NACK suppression Active contributions cache of data to allow local recoveries feedback aggregation subcast 41 A step toward active services: LBRM 42 Active local recovery routers perform cache of data packets repair packets are sent by routers, when available data data data5 data1 data2 data3 data4 data5 data1 data2 data3 data4 data5 data1 data2 data3 data5 43 Active feedback aggregation Routers aggregate feedback packets data4 only one NACK is forwarded to the source 44 Active subcast features Send repair packet only to the relevant set of receivers data4 45 Active Reliable Multicast Mechanisms Answer general questions such as Answer specific questions such as is active networking beneficial for multicast? where active components should be placed? in what proportion? how fast do they need to be? what mechanisms (global vs local NAK suppression, subcast facilities) for what performance? scalabity of the proposed solutions? Design of new multicast protocols 46 Network model F active routers among N. B receivers in a local group 2 kinds of receivers: linked and free 47 Benefit of global aggregation on throughput 48 Benefit of the source subcast facility 49 Impact of active router density 50 Conclusion Zut, j'aurais mieux fait de rester au séminaire!! 51 References D. L. Tennehouse, J. M. Smith, W. D. Sincoskie, D. J. Wetherall, and G. J. Winden. A survey of active network research. IEEE Communications Magazine, pages 80--86, January 1997. L. Wei, H. Lehman, S. J. Garland, and D. L. Tennenhouse. Active reliable multicast. IEEE INFOCOM'98, March 1998. M. Maimour, C. Pham. A Throughput Analysis of Reliable Multicast Protocols in an Active Networking Environment. TR. http://resam.univlyon1.fr/~cpham/Paper/TR/TR01-2000.ps.gz 52 Web links ANTS Tamanoir and active reliable multicast http://wind.lcs.mit.edu/activeware http://resam.univ-lyon1.fr Active Networking in France http://www.loria.fr/~festor/raf/raf.html 53