Packet Switching: LAN to WAN

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Packet Switching LAN to WAN
Tony Rybczynski Director of Strategic Enterprise
Technologies Tonyryb_at_nortel.com
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Packet Switching A General Definition

• Subdividing the overall message or bit stream
• Individually addressed packets
• Dynamic bandwidth
• Access and trunk multiplexing
• All traffic can burst at full pipe capacity
• Layered operation
• Application protocols above
• Seven Layer OSI model helps
• Packet switching applied at Layer 2 and 3
• Facilities below
• Exploitation of 'bursty' nature and tolerance to
  delays of most applications
• Functionality routing, flow control, error
  control, QoS

OSI Open System Interconnection QoS Quality of
Service
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Technical Drivers for Packet Switching

• Burstiness of all applications
• Data
• Voice
• Video
• Fiber optics explosion and price/performance
• IP and Ethernet optimized hardware switching
• Integration of routing, switching and multiplexing

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Circuit (TDM) vs Packet Switching
56Kbps
56Kbps
TDM on SONET

• Main differences (TDM vs packet)
• Fixed speed vs speed conversion
• Fixed delay vs variable delay
• Dedicated vs shared bandwidth
• Switching multiplexing vs integrated SM
• Call set up vs IP routing

10/100/1000Gbps
56Kbps, T1, T3
IP/fiber
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Many Faces of Packet Switching

• A set of technologies
• Switching multiplexing architecture
• Based on multi-byte packets
• Connectionless or connection-oriented paradigms
• Can ride on different media at varying speeds
• LAN/MAN/WAN/wireless networks
• A carrier service capability
• Basis for tariffed services
• Various service classes
• Connectionless (throughput, delay)
• Connection-oriented
• Multiple types of variable bit rate options
• Constant bit rate
• Unicast and multicast
• A set of standards
• Interface and networking standards
• User and network interface protocols
• Service definitions
• Performance metrics

LAN/MAN/WAN Local/Metro/Wide Area Net
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OSI Model

• 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 being added
• Layer 2 Link layer (Ethernet MAC, Frame
  Relay/ATM)
• Delimits the packet
• Variable time delay, error free
• Optional QoS, flow control and error recovery
• Link addresses (e.g.MAC address 0007E08CBB04)
• Layer 1 Physical Layer
• Transmission of a serial bit stream
• Dedicated path between two entities
• Shared path among multiple parties (e.g.
  wireless)
• Copper, fiber, wireless

OSI Stack
Application
Presentation
Session
Transport
Network
Link
Physical
MAC Media Access Control ATM Asynchronous
Transfer Mode TCP Transmission Control
Protocol UDP User Datagram Protocol RTP
Real-Time Protocol
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Network View
Mobile user
DSL Cable modem Ethernet
WLAN 3G CDMA/GSM
Home user
Private line, Optical Ethernet, FR/ATM, MPLS,
The Internet
Remote site
WAN VPN Router
Large campus backbone Campus core/distribution
Aggregation/Access Edge (Wiring Closet)
Campus backbone
Ethernet Routing Switches
Ethernet Switches
WLAN
Laptop
VPN Virtual Private Network DSL Digital
Subscriber Line 3G CDMA/GSM third gen public
wireless
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Nortel Carling Campus Network

• 5500 employees across 10 labs
• 10/100 and 10/100/1000 Mbps ports to desktops and
  servers
• Resilient QoS-enabled Ethernet switches in wiring
  closet
• Multiple redundant Ethernet Routing switches in
  backbone
• Hundreds of WLAN Access Ports
• gt100 Gbps uplink capacity and gtTbps switching
  capacity
• Layered defence for security

Applications VoIP, Email, Instant Messaging,
Video and audio streaming. Webcast Distributed
product development
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Formatting a Packet
Data to be transmitted
Packetized payload
HDLC High-level Data Link Control FTP File
Transfer Protocol
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Example Packet Formats
HDLC Trailer
Level 4-7 Headers
Level 3 Header
Layer 2 Header
Data (0-1500B)
Flag
Flag
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Queuing Model
output
inputs
10 5
Total time Service time
utilization 100

• Packet networks operate in a queuing model
• Congestion control is important to protect the
  network
• Buffer vs closed loop vs discard
• Quality of Service (QoS) mechanisms ensure
  priority given to time critical traffic
• Shorter maximum packet lengths lower queuing
  delays

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A Generic View of QoSNot all traffic is
created equal
Here is what my applications require from the
network

• Policing
• Ensures compliance with Service Level Agreement
  or Policy
• Shaping
• Improves efficiency and enforces conformance
• Scheduler
• Ensures flow gets desired bandwidth

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Routing Challenges in Packet Networks
Switch/ Router A
Switch/ Router A
Switch/ Router A
Switch/ Router A
Switch/ Router A

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

Routing system has two objectives gt Maximize
network utilization and minimize routing
convergence times gt Meet user/application needs
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Routing Options
Switch/ Router C
Switch/ Router A
Switch/ Router E
ltltRPgtgt
ltltRPgtgt
ltltRPgtgt
ltltRPgtgt
Switch/ Router B
Switch/ Router D
Routing Table is maintained and specifies what is
best link to take for each destination
ltltRPgtgt
Routing Protocol exchanges routing information
periodically

• Flat vs hierarchical (for scalability)
• Static routing
• Distance vector (e.g. hop count to each
  destination)
• Link state routing (each node has total network
  view)
• Load balancing
• Policy-based routing
• Per packet vs per flow
• Cost of links

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Packet Switching Performance Parameters

• Transit delay time from transmission to
  reception
• Access link delay (q time, emission time,
  propagation time)
• Network transit delay ( access switch trunk
  delay)
• Average vs variation
• Throughput
• Switch
• Trunk
• Access and/or connection throughput
• Measures of efficiency
• Processor and trunk utilization
• overhead for payload
• Challenges (like the 417)
• Traffic characterization (driver behaviour and
  prioritization)
• Protecting the network (maximizing cars/minute)

Networking objectives gt Maximize network
utilization gt Meet user/application needs
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Packet Switching Advantages/Disadvantages

• Bandwidth only consumed when needed
• Reduces cost of bandwidth
• Reduces cost sensitivity to distance
• Speed conversion
• 56Kbps modem access to 10GigE server
• Dynamic routing
• Connection
• Connectionless

• But ...
• Processing requirements during the session
• Complexity
• Routing algorithms
• Congestion control
• Protocols
• Variable delays

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Networking Technology Taxonomy
Switching Multiplexing
Circuit Switching TDM Multiplexing
Packet Switching Statistical Multiplexing
Connection- Oriented
Connectionless
Layer 3 IP
Layer 2.5 MPLS
Layer 2 Frame Relay/ATM
Layer 2 Ethernet
Copper/fibre MAN/WAN
Wired MAN
Wireless LAN/MAN
IP can run on any Layer 1 or Layer 2 network Some
networks are pure connectionless (e.g. extended
campus nets) Carriers are evolving to MPLS WANs
and Ethernet MANs
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Connection-Oriented vs. Connectionless

• Connectionless
• Terminology
• Layer 2 Ethernet frame
• Layer 3 IP packet
• Full address per packet
• Ethernet MAC address
• IP network address
• Routing/switching by per packet
• Multiplexing via full address in packet header
• Connection-oriented (Layer 2 or 2.5)
• Terminology
• Frame Relay frame over virtual circuit
• ATM cell over virtual circuit
• MPLS packet over label switched path
• Call Setup/Teardown/Status Signaling
• Routing/switching by per connection
• Multiplexing via short Connection-ids in packet
  header
• Frame Relay Logical Channel Number

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The Strength of Ethernet
Ubiquitous
Lowest cost data interface
Global Open Standard
Simple,plug play
The 1 interface for IP traffic
The 1 networking choice for Enterprises
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The State of The Art High-performance fail-safe
stacking Ethernet Switch for the Wiring Closet

• Dedicated bandwidth to each desktop
• Standard Carrier Sense Multiple Access (CSMA)/
  Collision Detection
• 100 meter range
• Broadcast domain over virtual LAN
• Flat MAC addressin space
• Power over Ethernet (for VoIP, WLANs)
• Rate adaptive interfaces
• Standard QoS
• Failsafe stackable architecture with 480Gbps
  capacity (or modular architecture not shown)
• Multilink Gigabit Ethernet multi-homed to
  backbone switches
• Going to 10GigE over fiber
• Sub-second failure recovery
• Security features (e.g. access control lists, end
  point security)

10/100/1000 Gbps Of Category 5 wiring
High-performance level maintained in case of a
switch failure
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Wireless Ethernet
Cell B
Cell A
Ethernet Switch
Workstation
Ethernet Segment (10BaseT or 10/100 autosense)
Access Point
Access Point Powered Over Ethernet

• IEEE 802.11 standards specify three modes 3
  channels at 11Mbps 3 channels at 54Mbps 10
  channels at 54 Mbps
• Standard Ethernet headers plus radio preamble
  signal up to 264 Bytes.
• Low power unlicensed operation over limited
  distances (lt100m indoors) hundreds of meters
• Carrier Sense Multiple Access CSMA/Collision
  Avoidance to control shared access

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Wireless Mesh Networks

• Most WLAN APs are AC powered without wired
  Ethernet connectivity
• WLAN APs have multiple antennas and radios for
  discovering neighbours and connecting to users
• Standard IEEE802.11 for user access
• Self organizing with auto recovery
• Dynamic routing over APs for extended coverage
• Secure inter-AP communications

Wireless Gateway
Access Point
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Optical Developments Driving Optical Ethernet

• Optical outpacing Moores Law
• Faster Wider Further Smarter Simpler
• 5x growth in metro optical
• Municipalities proactive on fiber deployment
• Utilities leveraging their rights of way
• Majority of multi-tenant buildings within 300
  meters of fiber

End-to-end Optical Ethernet MANs Ethernet on-ramp
to Internet and MPLS WANs
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Optical Ethernet in the MAN/WAN
Data Center
MPLS Backbone Or Internet
Ethernet On RPR
Ethernet On Fiber
Data Center
Ethernet On Lambdas
Reliability and Simplicity via Optical Ethernet
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Resilient Packet Rings (RPR)

• Logically a distributed Ethernet switch
• Ring-aware Media Access protocol with lt50msec
  protection
• Dual counter rotating rings with no packet loss
• Spatial re-use around the ring
• QoS enabled
• Support for SONET physical layers
• Metro SONET rings
• WAN SONET links
• IEEE 802.17 standardization

Combing the ubiquity of Ethernet with reliability
and scalability of optical
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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 (MPLS- MultiProtocol
  Label Switching, RSVP- Resource reSerVation
  Protocol)
• Full suite of application protocols (TCP, RTP,
  UDP)
• IPv6 coming!
• First Asia, public wireless and DoD
• Required for address scalability and increased
  security
• Multiple tunneling/encapsulation schemes defined
  to IP on any Layer 1/Layer 2
• Layer 1 copper, fiber, wireless
• Layer 2 frame relay/ATM, MPLS

OSI Stack
Application
Presentation
Session
Transport
Network
Link
Physical
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IP on Everything and Everything on IP
Data Voice Video Multimedia Gaming File
sharing IP TV Telemetry
Applications
Layer 4-7 IP Suite
Security
IP
Ethernet/FR/ATM/MPLS
Fiber DWDM SONET RPR
Copper
Wireless
RPR Resilient Packet Rings DWDM Dense Wave
Division Multiplexing SONET Synchronous Optical
NET
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Connection-Oriented vs. Connectionless

• Connectionless
• Terminology
• Layer 2 Ethernet frame
• Layer 3 IP packet
• Full address per packet
• Ethernet MAC address
• IP network address
• Routing/switching by per packet
• Multiplexing via full address in packet header
• Connection-oriented (Layer 2 or 2.5)
• Terminology
• Frame Relay frame over virtual circuit
• ATM cell over virtual circuit
• MPLS packet over label switched path
• Call Setup/Teardown/Status Signaling
• Routing/switching by per connection
• Multiplexing via short Connection-ids in packet
  header
• Frame Relay Logical Channel Number

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Second Generation Packet Frame Relay

• End-to-end Features
• Connection oriented
• Permanent Virtual Circuits PVCs
• Switched Virtual Circuits SVCs
• Committed information rate (CIR)
• Sequence preserving
• Standard adaptation for 80s protocols
• Physical Level
• Bit Rates To 10s of Mbit/s but 56 to 1.5 Mbit/s
  most common
• Link Level
• HDLC Framing
• CRC16 but no error recovery
• Multiplexing via Data Link Control Identifier
  (DLCI)
• Link establishment/clearing via signaling channel

Frame Relay is a the foundation of many
enterprise WANs
CRC Cyclical Redundancy Check
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Then for multimedia ATM

• End-to-end Features
• Connection oriented (PVCs--gtSVCs)
• Delay and loss critical classes of services
• Sequence preserving
• Standard adaptation for CBR via AAL1 and data via
  AAL3/4 and 5
• Physical Level
• Bit rates to Gbit/s but 45 150Mbit/s today
  (in-building in early 90s)
• Link Level
• 485 fixed length cells
• No error control and recovery
• Multiplexing via VCI/VPI

• Technology Enablers
• Fiber transmission
• High Speed Hardware
• -gt Multimedia networking
• -gt End-to-end broadband

ATM is a the legacy campus backbone of some
enterprise networks 150Mbps data center access
for Frame Relay networks Current carrier
multi-service backbones WANs (for voice, FR/ATM.
IP)
CBR Constant Bit Rate AAL ATM Adaptation
Layer VCI/VPI Virtual Circuit/Path Id
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ATM Traffic Management by Traffic Type
VBR Yes Yes Yes Yes Yes Yes No
ABR Yes No No No No No Yes
UBR No No No Yes No No No
CBR Yes Yes Yes Yes No No No
Cell loss ratio CTD Cell transit
delay CDVCell delay variation PCR peak cell
rate SCR sustained cell rate Burst tolerance _at_
PCR Flow control
VBR is split (real-time and non-real-time)
usage parameter control function connection
admission control function rate-based flow
control being standardized
Tight Control of QoS
VBR Variable Bit Rate ABR Available Bit
Rate UBR Unspecified Bit Rate
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ATM vs Frame Relay

• Both Connection Oriented
• Frame mostly data only
• Cell multimedia
• Access multiplexing for both
• Frame and cell relay sit on physical medium
• Frame relay (Kbit/s to Multi-Mbit/s)
• Cell relay (Multi-Mbit/s to Gbit/s)
• Framing
• Frame variable length HDLC
• Cell fixed length cells ATM Adaptation
• Service interworking via frame to cell gateways

Single service concept from Kbit/s to
Gbit/s Lowest common denominator is frame relay!
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MultiProtocol Label Switching (MPLS)
IP
ATM
MPLS
ATM control plane
IP routing software
IP routing software
Label swapping
Label Swapping
Forwarding
Covered in another lecture

• Leverages IP control plane for topology and
  addressing
• QoS defined for transport of IP traffic
• Leverages label swapping paradigm for traffic
  management

VPN Virtual Private Network
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Technology Layer 2 Application Map
Bandwidth (Mbps)
600 150
45 16 10 1
ATM switching
Ethernet
Frame relay
X25

LAN (CPE) MAN
WAN
Distance
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Whats Hot in Packet Switching?

• Expanding role of Ethernet across the LAN/MAN/WAN
  up to 10Gbit/s
• Making the IP networks more scaleable and
  improving economics
• Explosion in wireless
• Beyond 10 Gbps Ethernet (40 or 100?)
• Terabit switch routers (hardware/hardware/hardware
  )
• Connection-oriented capabilities to make large IP
  networks more manageable (via MPLS)
• Evolution/transition to IPv6 for end-to-end
  addressing scalability
• Security everywhere and integrated with routing
• Expanding application fit of IP networking
• Telephony and multimedia on wired and wireless IP
• Secure and reliable multicast
• Storage on IP
• More application-aware intelligence in the network

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