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					QoS in AB K12’s


        Todd Kennedy
                 ATLE
 Building Bridges Conf
     About the Speaker
 Married, three kids, oldest is
  12, youngest is 3.
 Director of Technology with
  Pembina Hills (11 years)
 MSc. IT University of
  Liverpool
              Introduction
 Mid 2004 - No SuperNet yet
 Dissertation Project for MSc
 Very few understood QoS
 Project meant as QoS
  Cookbook
 Technical Presentation
                   Agenda
 Issues with networking
 QoS methods
 Alberta SuperNet
 Five Connectivity Methods
 University Program
Issues with
Networking
            What is QoS?
 The ability of the network to
  provide better or “special”
  sevice to a set of
  users/applications to the
  detriment of other
  users/applications. - Cisco
Why do we need QoS?
 We don’t, for file transfers,
  web browsing, e-mail, 99%
  of tasks that most users do
 Except for Voice/Video or
  other delay/jitter sensitive
  traffic
Packet/Circuit Switching
               TCP/UDP IP
 TCP - rudimentary QoS, will
  re-transmit if packet is lost.
  Has some congestion
  management, but tends to
  slow down traffic
 UDP - connectionless,
  doesn’t verify receipt of
  data.
            So who cares?
 Standard networks pass
  packets on FIFO
 Non priority traffic can
  interfere with priority traffic
 Voice and Video have some
  very specific requirements
  But I have tonnes of
           bandwidth?
 Large amounts of bandwidth
  do not solve the simple
  problem of QoS
 Video Example
 No QoS over Internet
                       Delay
 Delay refers to the amount
  of time between when a
  packet begins it’s journey at
  the sender, and when it
  arrives at the receiver.
 Video - frozen picture
 Audio - Can’t tell if person
  has stopped talking, some
  VoIP will drop the call
Delay
                        Jitter
 The amount of variation in
  delay of packets traveling
  across a data network
 Ie. Packets sent at a rate of
  1 every 20 ms. If a packet is
  late, jitter is increased,
  conversation is broken up
 Some assume bandwidth
  fixes all of this.
              Packet Loss
 Internet loses between 2
  and 10% of all data traffic
 Lost traffic causes re-
  transmission, which
  increases jitter
 Voice and Video are
  unuseable with high packet
  loss
                 Best Effort
 Historically, all networks,
  and the Internet are Best
  Effort networks. That is, the
  network will do it’s best, but
  there is no guarantee
 LAN design - we try to
  overengineer.
     What do we need?
 In 2004/2005:
 64% of school jurisdictions
  were using or planning to
  start VC immediately
 24% using VoIP
             QoS Methods
 Queuing
 Initially routers had a single
  queue.
 Now routers and switches
  have multiple queues
 Best Effort Queue and other
  higher priority queues
       Queue Servicing
 Priority Queuing
 Four queues
 Higher queue always served
  before lower queue
 What if the high priority
  queue is always full?
         Queue Servicing
 Weighted Fair Queuing
 Up to 4096 queues
 Queues with lower volume, and
  higher priority, serviced more
  frequently
 Queue with higher volume, but
  lower priority, serviced less
  frequently
 Ensures even low priority
  queues get serviced
         Queue Servicing
 Low Latency Queuing
 Traffic delivered first from
  the LLQ
 Some devices will do
  policing via LLQ
         Queue Servicing
 Random Early Detection and
  Weighted Random Early
  Detection
 If a queue is getting too full,
  drop packets from the end
  of the queue, causing some
  senders to slow down
 Some traffic is treated
  unfairly
    Traffic Classification
 802.1p - assign physical port to
  a queue priority
 Very easy to do
 Traffic only prioritized on local
  network
 All traffic from the same device
  put in the same queue
 Non-priority traffic will fill up the
  queue
 Management issues
                       IntServ
 Resource Reservation Protocol
 Sender sends control message
  reserving bandwidth from
  sender to receiver
 All devices must agree and
  support it. If a single device
  does not, all is lost.
 Lots of network and CPU
  overhead
 Not very scalable
Differentiated Services
 Tag the packet on the edge,
  pass through the rest of the
  network
 All devices must agree on
  ingress
 All PHBs must be same
  throughout the network.
 Traffic can be reclassified
  through Diffserv domains
Differentiated Services
 Call Admission Control
  becomes critical
 Diffserv is sender control,
  not receiver control
QoS Architectures
       Alberta SuperNet
 Diffserv Classification on
  ingress
 MPLS Core
 Standard classes for
  everyone
       SuperNet Service
 Gold = max 150 ms one-
  way latency, max 50 ms
  jitter, < 0.1% packet loss
 Silver = max 400 ms one-
  way latency, max 50 ms
  jitter, <0.1% packet loss
 Bronze = max 1 second
  latency or jitter, <0.1%
  packet loss
SLA’s
          MPLS in Simple
 Packet given a label at the
  edge.
 Switched appropriately
  based on label
 Wire speeds, because
  switching can be done
  through an ASIC if
  necessary
What are K12’s
        doing?
               What’s up?
 Survey to all K12 Tech
  Contacts
 Interviewed staff at 6 school
  jurisdictions
 Found a number of setups
            Simple Setup
 Local network connected
  directly to SED.
 All traffic set to Bronze
 No CED
 No need for any QoS
Simple
 Setup
 Cascading QoS Zones
 CED will have some form of
  QoS
 May have non-QoS devices
  connected to switches below
  the CED
 QoS applications connected
  closer to CED
 Assumes not all applications
  require QoS
Cascade
    QoS
  Zones
Cascade
    QoS
  Zones
     Trusted Service V1
 Tag all traffic on your own
 Lose 30% bonus traffic
 But all bandwidth available
  all the time
 QoS assigned by switches
Trusted
Service
             Hybrid IPSec
 Existing IPSec VPN-based
  WAN
 Plus SuperNet (IPSec
  tunnels)
 Router passes non-QoS
  traffic to IPSec portion, QoS
  traffic to SuperNet portion
 All is Bronze
Hybrid
 IPSec
        End-to-End QoS
 All switches support QoS
  (Diffserv tagging)
 Relatively rare
 Costly, when so much traffic
  doesn’t require QoS
               Trusted V2
 Newer Service
 Allows self-tagging
 Still must define amounts of
  Gold, Silver, Bronze
 30% bonus available
Questions?
University of Liverpool
 http://www.uol.ohecampus.com
  /home/index.phtml
 100% online
 Eight modules + Dissertation
  Project
 Each module is 8 weeks long
 Variety of topics, some
  programming, some security,
  etc.
University of Liverpool
 Diverse instructors,
  classmates
 Different people each course
 Lots of time required
 MSc in
   Internet Computing
   Information Security
   Software Engineering
Thank you!

				
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posted:4/2/2011
language:English
pages:48