Packet Switching: LAN to WAN Wired to Wireless Consumer to Enterprise

Tony Rybczynski

Tonyryb@rogers.com

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Tony Rybczynski

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

B.Eng-EE (McGill) M.Sc- EE (U of Alberta)Life Senior Member of IEEE

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Why is Packet Switching So Important?

Packet switching is the dominant networking technology

in the Internet, in public wired and 4G cellular networks

Andin the wired and wireless enterprise

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Packet Switching in 3 Parts

>Part 1: The basic technology>Part 2: The enterprise perspective>Part 3: Not just connectionless packet

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Part 1: Circuit Switching (TDM) vs Packet SwitchingMain 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

Router

TDM Switch

Router

TDM Switch

Mux / DemuxMux / Demux

10/100/1000Gbps 56Kbps, T1, T3

56Kbps 56Kbps

IP/fibre

TDM on SONET

Packet Switching is a much more flexible and evolvable technology

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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• 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

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Packet Switching Time Line

1960s 1970s 1980s 1990s 2000’s Present

Research Nets for

robust datacomm

ARPAnet (‘72)Commercial X25 nets (‘76)

Ethernet (’80)Token ring et al

TCP/IP (’83)Academic Internet

Commercial Internet (’94)Frame relay/ATM

Voice and videoOver IPMobility

4G wirelessGaming

IPTVStorage/IP

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• 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• Interface and networking standards• User and network interface protocols • Service definitions• Performance metrics• Security• Adaptation and encapsulation standards

Many Faces of Packet Switching

“LAN/MAN/WAN”: Local/Metro/Wide Area Net

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OSI StackApplication

Presentation

Session

Transport

Network

Link

Physical

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)• Basic delivery with QoS optional

• Layer 2 Link layer (Ethernet MAC, HDLC)• Packet delineation• Variable time delay, error free• Optional QoS, flow control and error recovery• 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)

“TCP”: Transmission Control Protocol“UDP”: User Datagram Protocol“RTP”: Real-Time Protocol“MAC”: Media Access Control“HDLC”: High Level Data Link Control

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IP is THE Network Layer Standard

IP

Layer 4-7 ‘IP Suite’

Any Layer 2

Fiber DWDMSONET

Copper

Applications

Wireless

“DWDM”: Dense Wave Division Multiplexing“SONET”: Synchronous Optical NET

DataVoiceVideoMultimediaGamingFile sharingIP TVTelemetry

Security can be applied in all layers as appropriate

Network Layer

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OSI StackApplication

Presentation

Session

Transport

Network

Link

Physical

The Standard Layer 3… IPv4

• Origins >30 years ago (ARPAnet)• Connectionless/”datagram” networking (not sequence

preserving, lossy)• 4 Byte IP address per packet• Full suite of networking protocols

• 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)

• 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

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Data (0-1500B)Level 4-7Headers

Level 3Header

Layer 2Header

HDLCTrailerFlag Flag

Example: Packet Formats

Ethernet: 18 B (bytes) Point to Point PPP: 5B including opening sequence

IP: 20B (40B for IPv6) including two addresses

UDP: 8B including source/destination port addressesTCP: 20B including port addresses, sequence numbers and window controls; connection setup requires 3-way handshake

Layer 4

RTP: 12B including timestamps (for voice); more for data

Trailer (Layer 2): 2-4B CRC

“CRC”: Cyclical Redundancy Check

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utilization 100%

Total time

Service time

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inputs output

Queuing and Packet Switching

• Queuing introduces variable delays• Congestion control required to protect the network• Quality of Service (QoS) mechanisms for time critical

traffic

Switch/Router

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• Links can have • Different speeds• Different utilizations• Different delays• Different operational states (up or down)

Routing Challenges in Packet Networks

Switch/Router

“A”

Switch/Router

“C” Switch/Router

“E”

Switch/Router

“D”

Switch/Router

“B”

Application Server

Routing system has two objectives:1. Maximize network utilization and

minimize routing convergence times2. Meet user/application needs

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• 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

Routing Options

Switch/Router

“A”

Switch/Router

“C” Switch/Router

“E”

Switch/Router

“D”

Switch/Router

“B”

Application Server

Routing Table is maintained and specifies what is “best” link to take for each destination

<<RP>>

<<RP>>

<<RP>>

<<RP>>

<<RP>>

Routing Protocol exchanges routing information periodically

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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 utilization2. Meet user/application needs

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• 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

Packet Switching: Advantages/Disadvantages

But ...• Processing requirements per packet• Complexity

• Routing algorithms• Congestion control• Protocols

• Variable delays

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Part 2: The Enterprise Perspective

• To do more with less

• To drive employee productivity wherever they are

• To use IT to grow revenues

• 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.

Time

Time

Traffic

Applications

IT BudgetThe CIO’s dilemma

Threats

Business IT needs:

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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

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Example of Large Campus Network

• 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

Applications:Hundreds of business apps, Collaboration, Social networking, Email, Instant Messaging, Video and Audio Streaming

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Wireless Ethernet (802.11)

Ethernet Segment (10BaseT or 10/100 autosense)

EthernetSwitch

Access PointWorkstation

Cell “A” Cell “B”

Access PointPowered

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)

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LARGE CAMPUS

Campus core/distribution

Aggregation/Access

Edge (Wiring Closet)

Network View

Campus backbone

The Internet

DSLCable modemEthernet

Customer orTelecommuter

MobileuserWLAN & cellular

“VPN”: Virtual Private Network“DSL”: Digital Subscriber Line“3G CDMA/GSM”: third gen public wireless

WLAN

DatabaseApplication Server

Ethernet Switches

Ethernet Routing Switches

WAN VPN Router

Laptop

?Branches & remote sitesLarger sitesData centres

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Enterprise Inter-Site Connectivity Options

BusinessApps

&Storage

Remoteoffice

BranchHQData centres

Regional center

Campus networks

Branch networks

Service providers developed ‘Layer 2’ packet services:1. Ethernet services2. Multiprotocol Label Switching (MPLS)

Many Layer 1 options• Private lines• Dark fibre• Fibre rings with DWDM• SONET ringsLayer 2 Packet Services• Ethernet connectivityLayer 3 VPNs • MPLS and/or IPSec over public IP

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Part 3: Not Just Connectionless IP Packet

Circuit SwitchingTDM Multiplexing

Layer 2 Frame Relay/ATM

Layer 3 IP

Connectionless

Layer 2Ethernet

Packet SwitchingStatistical Multiplexing

Switching &Multiplexing

Layer 2.5 MPLS

Connection-Oriented

Copper/fibre MAN/WAN

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

Wired MAN

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Connection-oriented Packet

• 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

A

B

C

D E

Nailed up connections

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MultiProtocol Label Switching (MPLS)

• IP control plane for topology and addressing • QoS defined for transport of IP traffic• Label swapping paradigm for VPNs & traffic

management

ConnectionlessIP

Connection-orientedpacket

Connectioncontrol plane

Labelswapping

MPLS

IP routingsoftware

Forwarding

IP routingsoftware

Label Swapping

MPLS allowed carriers to meet enterprise needs, AND to address traffic management challenges in their public IP networks

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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

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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!

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A Parting Thought

Technology is not an end in itself!

It has to take you where the user wants to go

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For More InformationOn packet switchinghttp://en.wikipedia.org/wiki/Packet_switching

“Commercialization of packet switching (1975-1985): A Canadian perspective” by T.Rybczynski

On all things IPhttp://www.ietf.org/

On all things wired and wireless Ethernethttp://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