Bell Labs Advanced Technologies EMEAAT Proprietary Information © 2004 Lucent Technologies1 Overview contributions for D27 Lucent Netherlands Richa Malhotra Ronald van Haalen

Bell Labs Advanced Technologies EMEAAT 2 Overview of Lucent’s contribution to D27 Route management: Comparison of large Load- balanced networks with large Ethernet networks Resilience: Protection for load-balanced networks and comparing it to Ethernet QoS on Ethernet (most topics also hold for IP): –Scheduling –Policing, Marking and Queue management interaction and influence on achievable SLAs –TCP performance with SLA based policing

Bell Labs Advanced Technologies EMEAAT Proprietary Information © 2004 Lucent Technologies3 Resilience contributions for D27 Lucent Technologies Richa Malhotra, Ronald van Haalen

Bell Labs Advanced Technologies EMEAAT 4 Resilience for load-balancing Source Destination Link or node failure leads to loss of traffic Traffic

Bell Labs Advanced Technologies EMEAAT 5 Resilience for load-balancing Source Destination Use one or more parity streams for protection, if a link fails, the packets can be generated again at the destination by using the parity stream Traffic Parity stream

Bell Labs Advanced Technologies EMEAAT 6 Resilience for load-balancing Compare Ethernet and load-balancing resilience Ethernet Spanning Tree: –Loss of bandwidth because of protection –Restoration time Load-balancing parity: –Loss of bandwidth because of protection –No restoration time Perform simulations to compare the two schemes

Bell Labs Advanced Technologies EMEAAT Proprietary Information © 2004 Lucent Technologies7 QoS contributions for D27 Lucent Technologies Richa Malhotra, Ronald van Haalen

Bell Labs Advanced Technologies EMEAAT 8 QoS topics addressed Scheduling Policing, Marking and Queue management interaction and influence on achievable SLAs TCP performance with SLA based policing Focus – Metro Ethernet Networks –Issues also apply to IP networks

Bell Labs Advanced Technologies EMEAAT 9 Scheduling: Problem Background Basically 2 types of traffic –Stream (UDP), does not adapt to network resources, time-sensitive –Elastic (TCP), adapts to network capacity available, time insensitive Classes of service – stream inelastic, Elastic and Best Effort SLA (service level agreement)s will exist both for inelastic(UDP) and elastic(TCP) traffic streams. Guarantees have to be met for both.

Bell Labs Advanced Technologies EMEAAT 10 Problem Description Due to time-sensitive nature of UDP-stream traffic has to be given strict priority over TCP-elastic traffic If the load of the high priority UDP-stream traffic is not controlled it will starve the low priority TCP-elastic traffic and SLAs will not be met. Thus the load of high priority UDP-stream traffic has to be controlled. QUESTION: To what extent should this be controlled, and how will this influence the TCP-elastic traffic? Can we relate these two aspects with simple analytical expressions The analytical expressions can then be used for QoS control, integrated into the CP/MP for admission control and resource management. Probably monitoring techniques can make the performance estimations more time-dependant and accurate over time.

Bell Labs Advanced Technologies EMEAAT 11 Model High priority queue with stream traffic (UDP), Blocking Low priority queue with elastic traffic (TCP), No Blocking Fixed server capacity Processor sharing for low priority Scheduling: Strict priority Exponential arrivals with requests service length (file length or session length following a generic distribution Low priority traffic sees varying server capacity available for itself Capacity left over for low priority is shared over all low priority elastic flows Typical of TCP traffic: Within a SLA/customer flow the number of TCP flows are not controlled. TCP adapts to the network capacity available and reduces its rate. (We use flow level model)

Bell Labs Advanced Technologies EMEAAT 12 Results: Exponential Service requirements

Bell Labs Advanced Technologies EMEAAT 13 Achievable Service Level Agreements in Metro Ethernet Networks

Bell Labs Advanced Technologies EMEAAT 14 Problem Background Metro Ethernet Bridge Metro Ethernet Bridge Metro Ethernet Bridge Access Network 1 Access Network 2 Metropolitan Area Network Service Level Agreements Between Access networks (customers) and the public Metro network Bandwidth profile--CIR and PIR SLA enforced using policing (token bucket) Packet marking: used to distinguish between IN-profile and OUT-of-profile or OUT-of-profile but within excess rate Further on in the network packets might experience congestion in the queues (Queue management techniques)

Bell Labs Advanced Technologies EMEAAT 15 Achievement of SLAs influenced by 3 essential elements dropped PIR CIR Policing token bucket Marking 3 color Queue Management Dropping techniques at queue at time of congestion Threshold based

Bell Labs Advanced Technologies EMEAAT 16 Metro Ethernet Network(MEN) Simulator MEN simulator –Dual token bucket –Marking: red packets dropped immediately, packets green if conformant to CIR, yellow if not conformant to CIR but conformant to PIR –Queue manager: Soft hol based dropping If threshold is exceeded, further incoming yellow packets are dropped Ns2 TCP stack used to generate TCP traffic

Bell Labs Advanced Technologies EMEAAT 17 UDP (Poisson) traffic only Given traffic is Poisson with average arrival rate  Part of this traffic is conformant to CIR (green), part of this not-conformant to CIR but conformant to PIR (yellow) RESULT: Achieved throughput in proportion to the of each customer.

Bell Labs Advanced Technologies EMEAAT 18 TCP traffic With the given constraint MAIN RESULT: It is possible that one customer does not get its CIR while another customer gets more than its CIR

Bell Labs Advanced Technologies EMEAAT 19 TCP traffic example configuration & results Congested Link capacity =145, no dropping at token bucket When CIRs and PIRs of all customers are equal RESULTS are as good. Configured CIRConfigured PIRAchieved Throughput Customer Customer Customer Customer

Bell Labs Advanced Technologies EMEAAT 20 TCP traffic example configuration & results Congested Link capacity =145, with queuing at hosts, no dropping at token bucket Configured CIRConfigured PIRAchieved Throughput Customer Customer Customer Customer

Bell Labs Advanced Technologies EMEAAT 21 TCP traffic example configuration & results Congested Link capacity =145, no queuing at hosts, no dropping at token bucket Configured CIR Configured PIR Achieved Throughput Customer Customer Customer Customer

Bell Labs Advanced Technologies EMEAAT 22 Conclusion For UDP traffic only SLAs differentiation can be achieved For TCP traffic it is difficult to achieve SLAs and even assured rate (CIR) might not be guaranteed Next Steps –Investigate possible solutions for TCP –Integrate with TCP+token-bucket study

Bell Labs Advanced Technologies EMEAAT 23 TCP performance problems with SLA based policing

Bell Labs Advanced Technologies EMEAAT 24 Problem Background Metro Ethernet Bridge (over SDH/SONET) Metro Ethernet Bridge (over SDH/SONET) Metro Ethernet Bridge (over SDH/SONET) Access Network 1 Access Network 2 Metropolitan Area Network Service Level Agreements Between Access networks (customers) and the public Metro network Charac: Bandwidth profile--CIR and/or PIR The bandwidth profile of the SLA enforced by policing methods like token bucket TCP performance is considerably hampered with token bucket based enforcement of the SLA. (problem is generic and not specific to Ethernet based networks)

Bell Labs Advanced Technologies EMEAAT 25 Problem overview Scenario: One TCP flow Token bucket limits rate of sender Packets are dropped at tokenbucket if rate is exceeded With one TCP connection, the throughput is only a fraction of the provisioned rate! Simulator and initial insight: already developed in a different project 1 TCP connection Sender Receiver

Bell Labs Advanced Technologies EMEAAT 26 TCP problem with policing First step to achieving SLAs: problem exists irrespective of any congestion in the network In Nobel: –Work out possible solutions