Next Generation Networks Chapter 10

Knowledge Concepts QoS concepts Bandwidth needs for Internet traffic

Important Terms QoS Streaming video Compression MPEG Delay Jitter Latency Isochronous traffic IP switches CoS MPLS

Bandwidth and Expansion Internet traffic doubles every 11 months Traffic increases due to changing nature of applications—more video and music with high bandwidth Streaming video requires 3-7 Mbps Video compression MPEG standards

Broadband Requirements High speed and capacity From terabits to petabits! Bandwidth on demand Any time allocation Bandwidth reservation Guarantee of needed bandwidth Support of isochronous traffic Traffic with no tolerance for delay QoS Provide variable service levels

IP Networks Traditional routers not designed to handle high-speed/large scale network traffic Demand exceeds capacity of core, creates queue over-run Capacity over-load and lost packets Congestion and slow response times Routers send traffic to shortest path not least congested During congestion, routers can take minutes to recalculate a new route IP switching improves speed

ATM Provides for real-time traffic management Enables CoS and QoS Emerging class of terabit switch routers for backbone QoS accomdates priority control, cell loss and delay Implicit means the application chooses the required QoS Explicit means the network manager controls the decision

ATM Service Levels CBR (constant bit rate) for streaming video VBR (variable bit rate) for providing bandwidth according to allocation policy ABR (available bit rate) for service guarantees for average to peak traffic patterns UBR (unspecified bit rate) provides a best effort service

IP QoS IntServ—controls end-to-end packet delays Bandwidth reservation technique Applications request bandwidth from the host Uses FIFO queuing DiffServ—packets marked to receive special treatment Really CoS model Prioritizes streams and marks traffic so nodes can provide different levels of service Evolved from IntServ