© R. Jayanthan, K. Gunasakera 1999 Quality of Service in Multiservice Networks for Digital Economy R. Jayanthan & Kithsiri Gunasakera National IT Conference 1999 Technical Session - 4th September 1999

National IT Conference 1999Agenda Introduction Elements of QoS QoS and Class of Service QoS Techniques Conclusion

National IT Conference 1999Introduction What is up with my new 128 k ISDN line Internet Services

National IT Conference 1999Introduction Your call can not be connected due to congestion. Please try later ………. Public Switched Telephone Networks

National IT Conference 1999Introduction Oops... Enterprise Networks

National IT Conference 1999 Elements of QoS Availability Delay Propagation delay Link speed delay Queuing delay Hop count Delay Variation Throughput Packet loss rate

National IT Conference 1999 Elements of QoS Availability The reliability of the communication link. Specified as a percentage of time (e.g %) Also specified in terms of MTBF & MTTR (Mean time between failures / Mean time to repair) Delay Propagation delay Link speed delay Queuing delay Hop count

National IT Conference 1999 Elements of QoS Delay variation also called Jitter due to multi path data flow and retransmissions can be a problem in real time traffic viz. voice & video Throughput data transfer capacity of network devices and links Packet loss rate result of congestion in switching / routing devices.

National IT Conference 1999 QoS and Class of Service Traffic has to be classified before QoS can be implemented. Classification can be based on: Application / server device or user source / destination address (MAC / IP) Service (TCP/UDP port number) Definition of classes is a prime requirement for QoS implementation.

National IT Conference 1999 QoS Techniques Prioritization Bandwidth Reservation Congestion Control Traffic Shaping

National IT Conference 1999 QoS Techniques Prioritization Applying different priorities for different class of traffic on the outbound link. IEE 802.1p and 802.1q standards for LAN. Weighted fair queuing (WFQ) for WAN traffic. Discard eligible (DE) marking on Frame Relay traffic. CoS grading as CBR, rt-VBR, nrt-VBR, UBR and implementation of ATM adaptation layers (ALL) on ATM networks.

National IT Conference 1999 QoS Techniques Bandwidth Reservation Resource Reservation Protocol (RSVP) for IP traffic. Switched Virtual Circuits (SVC) in ATM and Frame Relay networks. Congestion Control Random Early Discard (RED) algorithm FECN and BECN mechanism in Frame Relay Traffic Shaping Removing the bursty nature of data traffic. Leaky bucket algorithm

National IT Conference 1999Conclusion Todays networks are for tomorrows applications. Therefore the network designers should pay sufficient attention to the QoS aspect to make their networks future proof, while protecting the investment.

National IT Conference 1999 Thank You