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Packet Switching: LAN to WAN Wired to Wireless Consumer to Enterprise Tony Rybczynski [email protected] Tony Rybczynski B.Eng-EE (McGill) M.Sc- EE (U of Alberta) Life Senior Member of IEEE 37 years in the industry • 10 years with Bell Computer Communications Group as packet switching pioneer • 4 years in Bell Northern Research in system engineering •23 years in Nortel Networks mostly in the enterprise business unit • Retired as Director of Strategic Enterprise Technologies (CTO Office) • Over 200 articles, monthly column in trade journal, the ‘Hyperconnected Enterprise’ (TMC) blog and contributor to 2 books • Lecturer in this course since 2000 2 Why is Packet Switching So Important? Packet switching is the dominant networking technology in the Internet, in public wired and 4G cellular networks And in the wired and wireless enterprise 3 Packet Switching in 3 Parts >Part 1: The basic technology >Part 2: The enterprise perspective >Part 3: Not just connectionless packet 4 Part 1: Circuit Switching (TDM) vs Packet Switching 56Kbps 56Kbps TDM on SONET Mux / Demux Mux / Demux TDM Switch TDM Switch 10/100/1000Gbps 56Kbps, T1, T3 IP/fibre Router Router Packet Switching is a much more flexible and evolvable technology 5 Main differences (TDM vs packet) • Fixed speed vs speed conversion • Fixed delay vs variable delay • Dedicated vs shared bandwidth • Separate vs integrated switching and multiplexing • Call set up vs IP routing Packet Switching: A General Definition • Message or bit stream subdivided into packets • Individually addressed packets • Dynamic bandwidth • Access and trunk multiplexing • Traffic bursts at full pipe capacity • Layered operation • Application protocols above • Transmission facilities/pipes below • Seven Layer OSI model helps- packet switching applied at Layer 2 and 3 6 • Exploitation of 'bursty' nature and tolerance to delays of most applications • Functionality: routing, flow control, error control, Quality of Service (QoS) … “OSI”: Open System Interconnection Packet Switching Time Line Ethernet (’80) Token ring et al TCP/IP (’83) Academic Internet Research Nets for robust data comm Voice and video Over IP Mobility ARPAnet (‘72) Commercial X25 nets (‘76) 4G wireless Gaming IPTV Storage/IP Commercial Internet (’94) Frame relay/ATM 1960s 7 1970s 1980s 1990s 2000’s Present Many Faces of Packet Switching • A set of technologies • Switching & multiplexing architecture • Packet formats • Connectionless or connection-oriented paradigms • Transportable on different media at varying speeds • LAN/MAN/WAN/wireless networks • A carrier service capability • Basis for tarriffed services • Unicast and multicast • A set of open standards • • • • • • 8 Interface and networking standards User and network interface protocols Service definitions Performance metrics Security Adaptation and encapsulation standards “LAN/MAN/WAN”: Local/Metro/Wide Area Net Scope of This Lecture • Layer 4-7 (TCP, UDP, RTP etc) • Layer 3 Network Layer (today IP) • IP addressing (e.g. 192.168.1.1) OSI Stack • Basic delivery with QoS optional Application Presentation • Session Layer 2 Link layer (Ethernet MAC, HDLC) Transport • Packet delineation Network • Variable time delay, error free Link • Optional QoS, flow control and error recovery Physical • Link addresses (e.g. MAC address: 0007E08CBB04) • Layer 1 Physical Layer (copper, fibre, wireless) • Transmission of a serial bit stream • Dedicated path between two parties • Shared path among multiple parties (e.g. wireless) 9 “TCP”: Transmission Control Protocol “UDP”: User Datagram Protocol “RTP”: Real-Time Protocol “MAC”: Media Access Control “HDLC”: High Level Data Link Control IP is THE Network Layer Standard Data Voice Video Multimedia Gaming File sharing IP TV Telemetry Applications Layer 4-7 ‘IP Suite’ Network Layer IP Any Layer 2 Copper Security can be applied in all layers as appropriate 10 Wireless Fiber DWDM SONET “DWDM”: Dense Wave Division Multiplexing “SONET”: Synchronous Optical NET The Standard Layer 3… IPv4 • OSI Stack Application Presentation Session Transport • Routing protocols (e.g. RIP- Routing IP, OSPF- Open Shortest Path First) • Multicast (e.g. IGMP- Internet Group Membership Protocol, DVMRP- Distance Vector Multicast Routing Protocol, MOSPF- Multicast OSPF, PIM- Protocol Independent Multicast) • QoS and traffic management (RSVP- Resource reSerVation Protocol) Network Link Physical • 11 Origins >30 years ago (ARPAnet) • Connectionless/”datagram” networking (not sequence preserving, lossy) • 4 Byte IP address per packet • Full suite of networking protocols IPv6 is starting to be deployed! • First Asia, public wireless and DoD • Required for address scalability (16 B addresses) and increased security (IPsec) “FTP”: File Transfer Protocol Example: Packet Formats Flag Layer 2 Header Level 3 Header Level 4-7 Headers Layer 4 Data (0-1500B) HDLC Trailer Flag Trailer (Layer 2): 2-4B CRC RTP: 12B including timestamps (for voice); more for data UDP: 8B including source/destination port addresses TCP: 20B including port addresses, sequence numbers and window controls; connection setup requires 3-way handshake IP: 20B (40B for IPv6) including two addresses Ethernet: 18 B (bytes) Point to Point PPP: 5B including opening sequence 12 “CRC”: Cyclical Redundancy Check Queuing and Packet Switching inputs Switch/ Router output 10 Total time Service time 5 utilization • • • 13 100% Queuing introduces variable delays Congestion control required to protect the network Quality of Service (QoS) mechanisms for time critical traffic Routing Challenges in Packet Networks Switch/ Router “C” Switch/ Router “A” Switch/ Router “B” Switch/ Router “E” Application Server Switch/ Router “D” • Links can have • Different speeds • Different utilizations • Different delays • Different operational states (up or down) 14 Routing system has two objectives: 1. Maximize network utilization and minimize routing convergence times 2. Meet user/application needs Routing Options Switch/ Router “C” Switch/ Router “A” <<RP>> <<RP>> <<RP>> Routing Protocol exchanges routing information periodically 15 Switch/ Router “B” Switch/ Router “E” Application Server <<RP>> <<RP>> Switch/ Router “D” Routing Table is maintained and specifies what is “best” link to take for each destination • Flat vs hierarchical (for scalability) • Static vs dynamic routing • Distance Vector (e.g. hop count to each destination) vs Link State Routing (each node has network view) • Per packet vs per flow • Added requirements • Load balancing • Policy-based routing • ‘Cost’ of links Packet Switching Performance Parameters • • • • Transit delay: time from transmission to reception • Access link delay (queuing time, emission time, propagation time) • Network transit delay ( access + switch + trunk delay) • Average vs distribution of delays Throughput • Switch • Trunk • Access • User application Measures of efficiency • Processor and trunk utilization • % overhead for payload Challenges (just like highway 417) • Traffic characterization (driver behaviour and prioritization) • Protecting the network (maximizing cars/minute) Networking objectives: 1. Maximize network utilization 2. Meet user/application needs 16 Packet Switching: Advantages/Disadvantages • Bandwidth only consumed when needed • Reduced cost of bandwidth • Reduced cost sensitivity to distance • Speed conversion • 56Kbps modem access to 100GigE server • Dynamic routing • Connection • Connectionless • Leveraging of end point processing • Flow and error control But ... • Processing requirements per packet • Complexity • Routing algorithms • Congestion control • Protocols • Variable delays 17 Part 2: The Enterprise Perspective Business IT needs: • To do more with less Traffic Time • To drive employee productivity wherever they are Threats Applications The CIO’s dilemma • To use IT to grow revenues IT Budget Time 18 • To use IT to anticipate customer requirements Large corporations want to leverage carrier IP and non-IP services, with best bang for the buck, control, security and reliability. Large Business and Government Organizations…. • have very large internal IP networks (often with private IP addresses) • are reluctant to expose their internal traffic to Internet insecurity etc • have economic access to raw bandwidth • can suffer large economic loss from network and security failures • need management control to respond to internal business owners and their customers 19 Example of Large Campus Network Applications: Hundreds of business apps, Collaboration, Social networking, Email, Instant Messaging, Video and Audio Streaming 20 • 5000 employees • 10,000 10/100 and 10/100/1000 Mbps ports to desktops and servers • Resilient Ethernet switches in 50 wiring closets (<100m to each desk) • 12 redundant Ethernet Routing switches in backbone • Hundreds of WLAN Access Points • >100 Gbps uplink capacity and >Tbps switching capacity • Layered security • Centralized control Wireless Ethernet (802.11) Cell “B” Cell “A” Ethernet Switch Workstation Access Point Ethernet Segment (10BaseT or 10/100 autosense) Access Point Powered Over Ethernet • Multiple standard modes: 3 channels @11Mbps; 3 channels @54Mbps; 10+ channels @54 Mbps; 13 channels @100Mbps • Low power unlicensed operation over limited distances (<100m indoors) 22 Network View DSL Cable modem Ethernet Customer or Telecommuter Mobile user WLAN & cellular ? The Internet Branches & remote sites Larger sites Data centres WAN VPN Router LARGE CAMPUS Campus backbone Campus core/distribution Aggregation/Access Ethernet Routing Switches Ethernet Switches Edge (Wiring Closet) WLAN Laptop Database Application Server 23 “VPN”: Virtual Private Network “DSL”: Digital Subscriber Line “3G CDMA/GSM”: third gen public wireless Enterprise Inter-Site Connectivity Options Campus networks Data centres HQ Regional center Branch networks Branch Business Apps & Storage Many Layer 1 options • Private lines • Dark fibre • Fibre rings with DWDM • SONET rings Layer 2 Packet Services • Ethernet connectivity Layer 3 VPNs • MPLS and/or IPSec over public IP Remote office Service providers developed ‘Layer 2’ packet services: 1. Ethernet services 2. Multiprotocol Label Switching (MPLS) 24 Part 3: Not Just Connectionless IP Packet Switching & Multiplexing Packet Switching Statistical Multiplexing ConnectionOriented Circuit Switching TDM Multiplexing Connectionless Layer 3 IP Layer 2.5 MPLS Layer 2 Frame Relay/ATM Layer 2 Ethernet Copper/fibre MAN/WAN 25 Wired MAN Wireless LAN/MAN • Carriers developed connection-oriented & connectionless ‘Layer 2’ packet services to meet enterprise needs • MPLS was also developed as carrier backbone technologies for enhanced traffic management capabilities Connection-oriented Packet D A E Nailed up connections C B • • 26 Connections could be frame (Frame Relay) or IP-based (e.g. MPLS) • Switching based on connection-ids (MPLS labels) Enterprise site-site IP runs over these connections • Segregation from public Internet • Handling of private enterprise IP addressing • Improved security and control • Economics of packet for enterprise connectivity MultiProtocol Label Switching (MPLS) MPLS allowed carriers to meet enterprise needs, AND to address traffic management challenges in their public IP networks Connectionless IP MPLS IP routing software IP routing software Connection control plane Forwarding Label Swapping Label swapping Connection-oriented packet • IP control plane for topology and addressing • QoS defined for transport of IP traffic • Label swapping paradigm for VPNs & traffic 27 management Let’s End With A Reality Check • Everything on IP and IP on everything • Simplification via bandwidth • Access is split across multiple technologies • Ethernet for desktops (may be displaced by WiFi) • WiFi for mobile hotspots • DSL, cable and some fiber to homes • 2-4G public wireless • Carrier backbones evolving to Ethernet MANs and MPLS WANs for public Internet and enterprise VPNs 28 What’s Hot in Packet Switching? • • Making IP networks more scaleable and improving economics • Explosion in broadband wireless including 802.11n • Beyond 10 Gbps Ethernet (40 or 100?) • Terabit switch routers (hardware/hardware/hardware) • Evolution/transition to IPv6 for end-to-end addressing scalability • Security everywhere Expanding application fit of IP networking • Sensors • 4G Internet-optimized public wireless • IPTV • Storage on IP • More gaming • Debate: application-fluent network intelligence Lots of Opportunities for You! 29 A Parting Thought Technology is not an end in itself! It has to take you where the user wants to go 30 For More Information On packet switching http://en.wikipedia.org/wiki/Packet_switching “Commercialization of packet switching (1975-1985): A Canadian perspective” by T.Rybczynski On all things IP http://www.ietf.org/ On all things wired and wireless Ethernet http://www.ieee.org/web/standards/home/index.html + Course lectures on: VoIP, Internet of Things, WiFi, Internet Technology and Large-scale IP Network Design Bon Voyage and Thank You 31