Transcript Packet Switching - Systems and Computer Engineering

Packet Switching
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
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Outline
> Packet technology
> The enterprise perspective
> Concluding remarks
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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
And
in wired and wireless home and
enterprise networking
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Why not a a fixed circuit to where
you want to go?
We call that “TDM” or
“circuit switching”
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Circuit Switching (TDM) vs Packet Switching
56Kbps,
T1, T3
56Kbps,
T1, T3
TDM on SONET
Mux / Demux
Mux / Demux
TDM Switch
TDM Switch
10/100/1000Gbps
56Kbps, T1, T3
IP/fibre
Router
Router
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 is a much
more flexible and evolvable
technology
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Packet Switching Taxonomy
Switching &
Multiplexing
Packet Switching
Statistical Multiplexing
ConnectionOriented
Circuit Switching
TDM Multiplexing
Connectionless
Layer 3 IP
Layer 2.5
MPLS
Layer 2 Frame
Layer 2
Ethernet
Copper/fibre MAN/WAN
Wired MAN
Wireless LAN/MAN
• Carriers developed connection-oriented packet services
• to meet enterprise needs
• to enhance traffic management capabilities
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Many Faces of Packet Switching
• A set of technologies
• Switching & multiplexing architecture
• Packet formats
• Transportable on different media at varying speeds
• LAN/MAN/WAN/wireless networks
• A service capability
• Tarriffed services for consumers and business
• Basis for enterprise connectivity
• A set of open standards
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Interface and networking standards
Unicast and multicast
User and network interface protocols
Service definitions
Performance metrics
Security
Adaptation and encapsulation standards
“LAN/MAN/WAN”: Local/Metro/Wide Area Net
Packet Switching: A General Definition
•
Message or bit stream subdivided into packets
•
Individually addressed packets provide:
• Dynamic bandwidth
• Access and trunk multiplexing
• Traffic bursts at full pipe capacity
•
Layered operation with
• Application protocols above
• Transmission facilities/pipes below
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•
Exploitation of 'bursty' nature and tolerance to delays of most
applications
•
Functionality: routing, flow control, error control, Quality of
Service (QoS) …
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
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1970s
1980s
1990s
2000’s
Present
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
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Wireless
Fiber
DWDM
SONET
“DWDM”: Dense Wave Division Multiplexing
“SONET”: Synchronous Optical NET
The IP Protocol Stack
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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 (no guarantees)
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)
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Layer 1 Physical Layer (copper, fibre, wireless)
• Transmission of a serial bit stream
• Dedicated path between two entities
• Shared path among multiple parties (e.g. wireless)
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“TCP”: Transmission Control Protocol
“UDP”: User Datagram Protocol
“RTP”: Real-Time Protocol
“MAC”: Media Access Control
“HDLC”: High Level Data Link Control
Queuing and Packet Switching
inputs
Switch/
Router
output
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Total time
Service time
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utilization
•
•
•
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100%
Queuing introduces variable delays
Congestion control required to protect the network
Quality of Service (QoS) mechanisms available for time
critical traffic
Routing Challenges in Packet Networks
Switch/
Router
“C”
Switch/
Router
“A”
Switch/
Router
“E”
Application Server
Switch/
Router
“B”
Switch/
Router
“D”
• Links can have
• Different speeds
• Different utilizations
• Different delays
• Different operational states (up or down)
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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
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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
The Standard Layer 3… IPv4
OSI Stack
Application
•
Presentation
Session
Transport
Network
• Routing protocols
• Multicast
• QoS and traffic management
Link
Physical
•
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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 defence networks
“FTP”: File Transfer Protocol
IPv6
 Defined in 1999
 Greatly expanded address space (vs 4.3B
addresses defined in IPv4)
 Historical imbalance in distribution of IPv4
addresses (NA vs Asia; early-adoptor large
corporations got huge address spaces)
 2B Internet users worldwide and growing
 Internet of Things explosion
 Network and end device implications
 Can co-exist with IP v4 networking
Next generation IP address
standard intended to supplement
and eventually replace IPv4
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IPv4 Protocol Stack 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
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“CRC”: Cyclical Redundancy Check
Packet Switching Performance Parameters
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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
• Traffic characterization (driver behaviour and prioritization)
• Protecting the network (maximizing cars/minute)
Networking objectives (just like the 417)
1. Maximize network utilization
2. Meet user/application needs
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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
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• Variable delays
• Small but finite P(packet loss)
Outline
> Packet technology
> The enterprise perspective
> Concluding remarks
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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
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• 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
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Example of Large Campus Network
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Applications:
Hundreds of business apps,
Collaboration, Social
networking, Email, Instant
Messaging, Video and Audio
Streaming
• 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)
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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
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“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)
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Connection-oriented MPLS Networking
D
A
E
MPLS connections
C
B
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IP-based Connections
• IP control plane for topology and addressing
• Switching based on connection-ids (MPLS labels)
Enterprise site-site IP can run over these connections
• Segregation from public Internet
• Handling of private enterprise IP addressing
• Improved security and control
• Economics of packet for enterprise connectivity
Outline
> Packet technology
> The enterprise perspective
> Concluding remarks
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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 MPLS backbones for improved public
Internet operations and enterprise VPNs
• Ethernet MANs for high speed Layer 2 connectivity
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What’s Hot in Packet Switching?
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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
• Security everywhere
Expanding application fit of IP networking
• Internet of Things
• 4 and 5G Internet-optimized public wireless
• More IPTV
• Storage on IP
• More gaming
Debate: pure Layer 3 vs 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 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:
MPLS, VoIP, Internet of Things, WiFi and Internet Technology
Bon Voyage and Thank You
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