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QoS in AB K12’s

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

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QoS in AB K12’s

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  1. QoS in AB K12’s Todd Kennedy ATLE Building Bridges Conf

  2. 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

  3. Introduction • Mid 2004 - No SuperNet yet • Dissertation Project for MSc • Very few understood QoS • Project meant as QoS Cookbook • Technical Presentation

  4. Agenda • Issues with networking • QoS methods • Alberta SuperNet • Five Connectivity Methods • University Program

  5. Issues with Networking

  6. 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

  7. 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

  8. Packet/Circuit Switching

  9. 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.

  10. 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

  11. But I have tonnes of bandwidth? • Large amounts of bandwidth do not solve the simple problem of QoS • Video Example • No QoS over Internet

  12. 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

  13. Delay

  14. 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.

  15. 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

  16. 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.

  17. What do we need? • In 2004/2005: • 64% of school jurisdictions were using or planning to start VC immediately • 24% using VoIP

  18. QoS Methods • Queuing • Initially routers had a single queue. • Now routers and switches have multiple queues • Best Effort Queue and other higher priority queues

  19. Queue Servicing • Priority Queuing • Four queues • Higher queue always served before lower queue • What if the high priority queue is always full?

  20. 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

  21. Queue Servicing • Low Latency Queuing • Traffic delivered first from the LLQ • Some devices will do policing via LLQ

  22. 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

  23. 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

  24. 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

  25. 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

  26. Differentiated Services • Call Admission Control becomes critical • Diffserv is sender control, not receiver control

  27. QoS Architectures

  28. Alberta SuperNet • Diffserv Classification on ingress • MPLS Core • Standard classes for everyone

  29. 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

  30. SLA’s

  31. 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

  32. What are K12’s doing?

  33. What’s up? • Survey to all K12 Tech Contacts • Interviewed staff at 6 school jurisdictions • Found a number of setups

  34. Simple Setup • Local network connected directly to SED. • All traffic set to Bronze • No CED • No need for any QoS

  35. Simple Setup

  36. 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

  37. CascadeQoSZones

  38. CascadeQoSZones

  39. Trusted Service V1 • Tag all traffic on your own • Lose 30% bonus traffic • But all bandwidth available all the time • QoS assigned by switches

  40. TrustedService

  41. 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

  42. Hybrid IPSec

  43. End-to-End QoS • All switches support QoS (Diffserv tagging) • Relatively rare • Costly, when so much traffic doesn’t require QoS

  44. Trusted V2 • Newer Service • Allows self-tagging • Still must define amounts of Gold, Silver, Bronze • 30% bonus available

  45. Questions?

  46. 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.

  47. University of Liverpool • Diverse instructors, classmates • Different people each course • Lots of time required • MSc in • Internet Computing • Information Security • Software Engineering

  48. Thank you!

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