Networking For the Future

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Networking For the Future

• By
• Dr. Junaid Ahmed Zubairi
• Sigma Xi Brown Bag Seminar
• Oct 3rd, 2003 at 12 Noon

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Overview of Presentation

• The Evolution of Internet
• The Types of Traffic on the Internet
• Performance Issues in Packet Switching
• The World Wide Web
• Changing Traffic on the Internet
• The Birth of ATM!!
• ATMs Service Classes and Layers
• Intserv, Diffserv, MPLS, TE
• GMPLS
• Future Network

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Fig 1 The Evolution of Internet Past and PresFu
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Seminar References

• Computer Networking A Top Down Approach
  Featuring the Internet by Kurose and Ross,
  Addison Wesley 2001
• ATM With X-Cell, XYLAN Course 701, XYLAN Inc.
• Computer Networks A Systems Approach Peterson
  and Davie, Morgan Kaufmann 2000
• Computer Networks Andrew Tanenbaum Prentice Hall
  1996

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The Evolution of Internet

• DARPA (Defense Advanced Projects Research Agency)
  funded the development of the Internet.
• The first working network was ARPAnet that was
  started in 1969 between four nodes
• The emphasis was on developing a robust network
  that would continue to function even if some of
  its parts were bombed out

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The Evolution of Internet

• email,
• usenet,
• file transfer and
• remote login were the main Internet applications

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Types of Traffic on the Internet

• These applications generated almost identical
  traffic stream on the Internet
• This traffic required reliability.
• The protocols were expected to deliver all the
  data no matter how long it took

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Performance Issues in Packet Switching

• The TCP/IP suite of protocols breaks the data
  into datagrams or packets and routes each packet
  through an independently selected path
• Packets may arrive at the destination out of
  sequence but due to buffering and re-ordering,
  the actual data can be recovered easily

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Message Text

• Dear John
• I agree with your suggestions. I think we may
  want to include Mike in the discussion. I am
  forwarding this message to him as well. He is an
  expert in this area and we should wait for his
  comments before proceeding forward on this
  project.
• Junaid

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Message Broken Down
Dear John I agree with your suggestions. I think
we may want to include Mike in the discussion. I
am forwarding this message to him as
Packet 1
well. He is an expert in this area and we should
wait for his comments before proceeding forward
on this project. Junaid
Packet 2
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Pkt2
Pkt1
Fig 2 Packets may follow longer paths and arrive
later than expected
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Pkt2
Pkt1
Fig 2 Packets may follow longer paths and arrive
later than expected
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Pkt2
Pkt1
Fig 2 Packets may follow longer paths and arrive
later than expected
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Performance Issues in Packet Switching

• Selecting a path is called routing and the
  intermediate nodes from source to destination are
  called routers
• Each router builds up a routing table to keep
  track of reachable destinations
• If more than one path is open to destination, the
  router may select the best path

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Performance Issues in Packet Switching

• Path selection criterion is usually shortest path
  first
• If the shortest path is congested or unreliable,
  the router can choose another path
• The traffic is bursty and it can increase or
  decrease abruptly based on the way the Internet
  is used

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Performance Issues in Packet Switching

• Given this scenario, a router may find itself
  overwhelmed with a lot more packets than it can
  handle
• Usually routers would use simple FIFO scheme to
  select the next packet to be transmitted from a
  queue of packets

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Router Exposed
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Performance Issues in Packet Switching

• If the queue is full, the newly arrived packets
  must be dropped (or discarded)
• Thus increase in traffic may increase time-outs,
  retransmissions and decrease in efficiency
• Usually, congestion in the network results in
  delay and loss penalties
• Congestion builds up due to bursty users, no
  active resource allocation and selfish users
  trying to monopolize the bandwidth

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Performance Issues in Packet Switching

• Traditional TCP/IP based Internet can be
  described as
• Best Effort
• One Size Fits All
• Hardly Any Service
• World Wide Wait

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The World Wide Web

• Web deployment is flexible and easy
• Due to the web technologies, the Internet has
  been put to use in almost all areas of human
  knowledge
• For example, water distribution monitoring,
  real-time traffic maps of big cities, free long
  distance calling, distance learning with lecture
  videos, buying and selling shares, online
  shopping etc., the list appears endless

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The Changing Traffic on the Internet

• Due to the web enabled applications on the
  Internet, there has been a tremendous change in
  the types of traffic
• Now we have to deal with a significant amount of
  traffic that is time-sensitive
• For example, consider the case of an audio based
  application that needs to transmit the data
  across the Internet

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The Changing Traffic on the Internet
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The Changing Traffic on the Internet
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The Birth of ATM!!

• As the users started to use the web for
  time-sensitive applications, they did not get
  what they wanted--- a consistent acceptable
  performance
• On some occasions, the network would give the
  best performance and on other occasions, it would
  be horrible in terms of delays and lost packets

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The Birth of ATM!!

• In this scenario, ATM offered a great promise to
  the users
• ATM standards started taking shape in mid-1980s
  as telcos pushed for integrating voice, video and
  data networks
• ATM was developed with the right targets and in
  mid-1990s, it offered the much awaited
  performance assurance

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What is ATM?

• ATM
• Is a cell-switching and multiplexing technology
  that combines the benefits of Circuit Switching
  (consistent transmission delay and guaranteed
  bandwidth) with those of Packet Switching
  (flexibility and efficiency for intermittent
  traffic).

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Why is ATM needed?

• Need to mix data, voice, and video traffic.
• We cannot just throw more bandwidth at the problem

Switch
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Why is ATM needed?

• All data packets are fragmented into fixed size
  cells
• Segmentation re-assembly only occurs at end
  stations
• Time critical traffic on segment A only has to
  wait for the current cell of Bs data packet to
  be sent before it can get the wire and be
  transmitted
• The ability to interleave cells from different
  messages is instrumental to the operation of ATMs
  QoS.

A B
C
Switch
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ATM Cell

• Small Cells - 53 bytes long
• 5 byte header
• 48 byte payload
• Fixed Length Fast Switching
• Fixed Length Contracts can be established and
  QoS maintained

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AAL Types

• AAL1 is for circuit emulation
• Class A - constant bit rate and time sensitive
  traffic
• AAL5 is for compressed video and data (used in IP
  over ATM)
• Class B - variable bit rate and time sensitive
  traffic
• Class C - variable bit rate (e.g., Frame Relay)
• Class D - variable bit rate, connectionless

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Service Categories

• Categories are based on type of traffic and type
  of service
• CBR Constant Bit Rate -Voice
• rt-VBR Real-Time Variable Bit Rate -Video
• nrt-VBR Non-Real Time Variable Bit Rate -Frame
  Relay
• ABR Available Bit Rate -Data
• UBR Unspecified Bit Rate -Data

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Traffic Management
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Traffic Management

• Two opposing views
• Enforce several rules in order to regulate the
  traffic and adapt to the available bandwidth
• Add more bandwidth
• For example, highways enforce HOV rule, speed
  limits, traffic light controlled ramps to enter
  the highway etc. OR autobahns with no such rules

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CAC
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VPIs and VCIs

• Virtual Path Identifier (VPI)
• Virtual Circuit Identifier (VCI)

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Traffic Shaping and Policing

• In order to meet the QoS contract obligations,
  ATM network enforces traffic shaping and policing
• Shaping involves techniques such as Leaky Bucket
  Algorithm to regulate bursty traffic
• Policing means marking CLP (Cell Loss Priority)
  on the offending cells that violate the maximum
  rates agreed

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Leaky Bucket Algorithm
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Why ATM Failed!!

• ATM failed because of several factors
• ATM is too complex (From packets to cells to
  SONET frames, using AALs, emulating LAN)
• ATM is expensive
• Ethernet has evolved into much faster 100Mbps and
  1000Mbps services
• All popular and established network applications
  are packet based
• ATM is down but not out. It is used in the telco
  cores

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Life after ATM

• IETF (Internet Engineering Task Force) is a very
  large organization with thousands of members
• IETF identified the problems with the traditional
  Internet and engaged in a long and continuing
  effort to improve the services and management

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Quality of Service

• New applications need performance and resource
  assurance
• Service differentiation is also needed so that
  the traffic from different applications is
  treated in service-appropriate way
• Resource assurance and service differentiation
  means QoS (Quality of Service)

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IETFs Models

• Targets
• Internet should be run in a way that there is no
  congestion
• Applications should be able to reserve or obtain
  network resources at a given QoS
• IETF has been working on developing new models
  and protocols for the Internet
• During the last decade, Intserv and Diffserv
  models have been developed

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Integrated Services

• Intserv stands for Integrated Services and
  requires reservations before transmission
• To receive resource reservation, an application
  describes its requirements
• The network determines a path based on the
  request

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Reservations, Reservations, Reservations
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Intserv

• A reservation protocol is used to install the
  reservation state along the selected path
• The reservation setup protocol in the Intserv
  model is the RSVP (Resource ReSerVation Protocol)

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RSVPs Services

• RSVP offers two types of services
• CONTROLLED LOAD service means that the service
  offered to a flow in an overloaded network is the
  same as it would get in a lightly loaded network
• GUARANTEED SERVICE is when a flow gets hard
  guarantees on the delay it will suffer

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RSVP Problems

• RSVP relies on extensive signaling for obtaining
  flow reservations along a path.It also entails
  soft state overhead and therefore does not scale
  well to the Internet
• Most of the Internet traffic consists of
  short-lived web transactions. It will be unwise
  to go through reservations for such traffic
• RSVP may be successfully deployed in a campus
  network but not on the global network

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IETFs DiffServ Model

• Intservs problems prevented its deployment
• IETF started developing a new model in 1997 to
  provide differing levels of service to different
  applications without the overhead of signaling
  and state maintenance
• The DiffServ model uses the TOS field in IPv4
  header to affix labels on packets belonging to
  different service levels
• DiffServ has the potential to offer QoS on the
  Internet, at last!!

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IETFs DiffServ Model

• Consider a gas station, you can buy regular,
  super or premium gasoline from the same pump
• DiffServ offers various service levels to the
  customer from the same network with SLA
• DiffServ adopts techniques used in ATM for
  traffic management, in a simplified way

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No Reservations Ever!!
VIP
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Diffserv Outline

• Diffserv works on the basis of dividing the
  traffic into a small number of forwarding classes
• For each FEC, the amount of traffic entering the
  network is controlled at the edge of the Diffserv
  network
• FECs are prioritized, with each one coded into
  the IP headers TOS byte. Core routers offer
  priority treatment based on the coding

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Diffserv Edge Router Functions
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Per-Hop Behaviors

• IETF has defined two DS services that are visible
  as PHB (per-hop-behavior) of an intermediate
  router for the marked packet
• EF (Expedited Forwarding)
• EF is the premium service offered. It can appear
  as a virtual leased line for the customer. It
  offers low loss/latency and assured bandwidth
• http//www.ietf.org/rfc/rfc2598.txt

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Per-Hop Behaviors

• AF (Assured Forwarding)
• The AF PHB group provides delivery of IP packets
  in four independently forwarded AF classes.
  Within each AF class, an IP packet can be
  assigned one of three different levels of drop
  precedence. A DS node does not reorder IP packets
  of the same microflow if they belong to the same
  AF class.
• http//www.ietf.org/rfc/rfc2597.txt

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Hybrid Approach
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MPLS

• MPLS was developed to map IP over ATM because the
  core routers use ATM. MPLS has additional
  features that are too exciting to ignore
• In MPLS, a short fixed length label is encoded
  into the packet
• The intermediate LSR (Label Switched Router)
  finds the next hop from a table, using the label
  as an index

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MPLS

• If the LSR is an ATM switch, label is just the
  VPI/VCI identifier
• If the LSR is an IP router, the label eliminates
  the destination based routing and reduces the
  router to a label switch
• A label switched path (LSP) must be set up prior
  to the start of transmission

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LSP Hierarchy
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LSPs in an MPLS Network
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MPLS TE

• Instead of routing, now the routers do label
  switching, a much faster job
• Network manager can decide LSPs (label switched
  paths) based on load distribution and other
  administrative goals
• Directing traffic on paths not determined by
  traditional IGPs provides flexibility and load
  balancing. It is known as TE (Traffic Engineering)

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MPLS AND TE

• MPLS runs constrained routing to determine an LSP
  within an MPLS domain.
• LSP may have some QoS features, based on the
  algorithm used
• The path could be strictly specified or loosely
  outlined and backup paths may be specified for
  handling link failures

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Automated Provisioning

• The networks are growing bigger!!
• The protocols are becoming more complex
• With Diffserv, MPLS, RSVP-TE, CR-LDP, COPS and
  associated protocols, it is impossible to allow
  manual provisioning
• Therefore, there is a need for automated TE-based
  path selection algorithms

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QoS Traffic Considerations

• If only the available bandwidth is considered,
  the class of service may not be taken into
  consideration
• Thus, the best effort traffic may intersect the
  QoS traffic at several points within the domain
• In Diffserv, this may be a recipe for disaster!!

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TELIC

• An efficient dynamic traffic engineering
  algorithm is developed for selecting paths across
  an MPLS-Diffserv domain
• TELIC (Traffic Engineering with Link Coloring)
  works with a set of traffic requests present at
  an ingress router of such a domain
• It allocates paths to an egress node using
  Dijkstras shortest path algorithm

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TELIC

• Each request specifies the amount of bandwidth
  requested followed by the Diffserv class of
  service (EF,AF,DF)
• While processing a request, TELIC partitions the
  network into several monochromatic subgraphs and
  makes an effort to match the request with an
  appropriate subgraph

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TELIC

• In case a subgraph has no path to the egress
  node, TELIC merges it with another subgraph as
  per rules carefully built-in and starts the
  search all over again
• In case a search is exhausted, rules are
  available to deallocate a best effort class LSP
  and start the search again
• TELIC is written as a flexible tool in C

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GMPLS

• The Internet backbone must use optical switching
  instead of electronic switching to handle the
  projected huge bandwidth
• MPLS cannot handle non-packet switching
• Recently the industry has gravitated towards
  GMPLS (Generalized MPLS) as the control plane
  solution for automatic lightpath setup and
  teardown in optical networks
• GMPLS is an extension of MPLS
• GMPLS allows control and provisioning of
  non-packet devices

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Why Optical Networking? (Courtesy Prof. Raj Jain
Ohio State University)
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GMPLS Layers (Courtesy Prof. Raj Jain Ohio State
University)
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GMPLS

• Using GMPLS, it is possible to perform switching
  based on
• Wavelengths
• Wavebands
• Timeslots
• Ports
• And Labels

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GMPLS

• For example, in an all-optical switch, there may
  be thousands of tiny mirrors that can be moved by
  miniature motors
• Switching can be done by adjusting a mirror so
  that light entering from one fiber can be
  reflected (switched) to the desired path forward

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LMP

• A link management protocol has been developed for
  GMPLS. It provides link provisioning, fault
  isolation and link aggregation
• Selection of label in MPLS ? Selection of
  wavelength and OXC port in GMPLS
• MPLS LSP ? GMPLS lightpath
• Before GMPLS, control and provisioning of optical
  network could take weeks!!
• Vendors were also reluctant to de-provision due
  to any changes

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End to End Provisioning
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Ubiquitous Networking

• The future of networking is being defined today.
  It is planned as a global network with no breaks
  or bumps
• Users may roam around with notebooks and remain
  connected wherever they go!!
• The realization of this goal calls for a global
  wireless network, global wired network and an
  interface between the wired and wireless networks

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Mobile Networking

• Mobile networking is developed rapidly with IEEE
  802.11and Bluetooth standards
• Let us take a look at the various configurations
  possible with IEEE 802.11

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Wireless LAN with access point under IEEE 802.11
Ad-hoc network
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Issues

• Several issues are being investigated for
  improving Wireless LAN functionality
• For example, how to perform transparent handoff ?
• How to perform routing in an ad-hoc network?
• How to shape and mark the traffic to esnure good
  QoS?

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Bluetooth

• Bluetooth is more focused on connecting
  electronic gadgets like digital cameras, mobile
  phones, printers, mouse etc. with each other and
  with the computer
• It replaces infrared line-of-sight type of
  connection
• It faces tough competition from UWB (ultra
  wideband), a similar technology but much faster
  than Bluetooth

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Future Network

• We envision a global ubiquitous network with
  instant access to email and the web from anywhere
  in the world
• With tremendous capacity, the network would offer
  the desired quality of service to our multimedia
  applications
• Traditional phone network will become a tiny
  section of the overall Internet
• Videophone over the Internet is expected to be
  the next killer app
• Privacy?? Huh