1. CS 447 Network & Data Communication QoS Implementation for the Internet IntServ and DiffServ Department of Computer Science Southern Illinois University Edwardsville Fall, 2013 Dr. Hiroshi Fujinoki E-mail: hfujino@siue.edu QOS_PART2/001

2. CS 447 Network & Data Communication QOS_PART2/000 Two existing QoS implementations for the Internet QoS implementation in the Internet IntServ (Integrated Service) DiffServ (Differentiated Service)

3. CS 447 Network & Data Communication QOS_PART2/000 IntServ IntServ controls QoS parameters by reserving resources at routers It is a virtual-circuit approach on top of datagram Internet By using a new add-on protocol, RSVP (developed by Intel) (RSVP = Resource Reservation Protocol) Combination of admission control & traffic policing “flow-oriented” QoS control (“per-flow QoS control”) Router RSVP request for reserve resources Reserve resources Reserve resources Reserve resources Reserve resources Positive ACK HTTP

4. CS 447 Network & Data Communication QOS_PART2/000 IntServ “flow-oriented” QoS control A logical pipe must be created for each flow After the mid 90’s, user population in the Internet started exploding After the mid 90’s, many different types of network applications were introduced Huge number of pipes must be managed by each IntServ router (scalability problem) IntServ uses a strict policing Network traffic that violates its promise is all dropped IntServ was not easy to use

5. CS 447 Network & Data Communication DiffServ Datagram approach (“packet-based QoS control”)  No admission control  No new QoS protocol is needed (because IP network (the Internet) is a datagram packet switching network) (no signaling) - Extends “TOS” filed in the IP header QOS_PART2/000 TCP Datagram (TCP packet) TCP Header (implemented on top of TCP)

6. CS 447 Network & Data Communication QOS_PART2/000 DiffServ Not “flow-oriented” QoS control Datagram approach - No admission control - No new QoS protocol is needed (because IP network (the Internet) is a datagram packet switching network) - DiffServ routers classify on-going traffic to groups of network traffic that has similar QoS requirements Mainly implemented by classifier, policing, shaping and scheduler at each router Many router venders, such as CISCO, implement DiffServ (no signaling) - Extends “TOS” filed in the IP header

7. TCP Device Driver IP DiffServ CS 447 Network & Data Communication QOS_PART2/000 Internal organization of DiffServ Device Driver NIC Routing Classifier Device Queue (managed by OS) NIC (FIFO Queue) Policing Shaping Policing Shaping Policing Shaping      DiffServ Queues (managed by Diffserv)      Scheduler - Traffic shaping & policing - Queues & scheduler - Buffer (queue) management

8. CS 447 Network & Data Communication QOS_PART2/000 Traffic Shaping & Policing  Packet Marker + Buffer Manager  Token Bucket + Buffer Manager Perform traffic policing only Perform both traffic shaping and policing

9. CS 447 Network & Data Communication QOS_PART2/000  Packet Marker + Buffer Manager Traffic Load (in bps) Time T Min All marked as “BLUE” All marked as “RED” All marked as “YELLOW” T Max Immediately drop T Acceptable

10. CS 447 Network & Data Communication QOS_PART2/000  Packet Marker + Buffer Manager ClassifierMarker DiffServ Queue When the DiffServ queue becomes full, what should be done? Buffer Manager If there are multiple packets of the same color (only one color), If there is no red packet, drop one yellow If there is no red or yellow packet, drop one blue If there is a red packet, drop one red (from tail, or top or middle of the queue)

11. CS 447 Network & Data Communication QOS_PART2/000  Token Bucket + Buffer Manager

12. CS 447 Network & Data Communication QOS_PART2/000 Global Synchronization and RED Queue Classifier Marker DiffServ Queue When the DiffServ queue becomes full, what should be done? Queue Length Max Packet Drop Probability 1.0 (100%) Is this bad?

13. CS 447 Network & Data Communication QOS_PART2/000 Global Synchronization and RED Queue Router The queue becomes full TCP detects a packet loss TCP detects a packet loss TCP detects a packet loss TCP detects a packet loss DiffServ Queue

14. CS 447 Network & Data Communication QOS_PART2/000 Global Synchronization and RED Queue Router The queue becomes full DiffServ Queue I slow down! I slow down! I slow down! I slow down!

15. CS 447 Network & Data Communication QOS_PART2/000 Global Synchronization and RED Queue Aggregated Throughput of a DiffServ queue (in bps) Time the buffer becomes full Global synchronization Everyone has backed off TCP slow-start in progress Average queue throughput Available Tx bandwidth Wasted transmission bandwidth

16. CS 447 Network & Data Communication QOS_PART2/000 RED (Random Early Detection) Queue Queue Length Max Packet Drop Probability 1.0 (100%) Queue Length Max Packet Drop Probability 1.0 (100%) Min RED Queue

17. RED (Random Early Detection) Queue CS 447 Network & Data Communication QOS_PART2/000 Router Someone’s packet BEFORE queue becomes full! DiffServ Queue I am OK! I slow down! I am OK!

18. CS 447 Network & Data Communication Aggregated Throughput of a DiffServ queue (in bps) Time the buffer becomes full Global synchronization Everyone has backed off TCP slow-start in progress Average queue throughput Available Tx bandwidth Wasted transmission bandwidth the buffer becomes full QOS_PART2/000 RED (Random Early Detection) Queue