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Design Review. Specifications. Minimum 64 port OC-48, aggregate capacity of 160Gbps, Fair Queuing. Extra RED MPLS, QoS Multicast Scalability. Components. Input Port processing (IPP) Buffers Switch Scheduling Output port processing Fair Queuing. Input Port Processing.
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Specifications • Minimum • 64 port OC-48, aggregate capacity of 160Gbps, Fair Queuing. • Extra • RED • MPLS, QoS • Multicast • Scalability
Components • Input Port processing (IPP) • Buffers • Switch Scheduling • Output port processing • Fair Queuing
Input Port Processing • Line termination and data link processing • Break variable length packet into fixed length • Lookup routing information • Process packets at "line speed” i.e. close to 5 million routing lookup per second. • Do simple IP packet processing functions • Decrease TTL, Checksum etc. • MPLS or Hardware Filters
Possible Solutions for IPP • Transceiver for line termination and PHY processing • HFCT-5402D by Agilent (HP) • VSC8140 by Vitesse • Framer for fixed size cells • VSC9112 by Vitesse • Network Processor • IXP1200 by Intel (Level One) • APP1200 and APP1400 by Agere • Generic micro-processor
Where to Queue? • Input port • Does not require high fabric speedup. • OPP can be done at reasonable speeds • Difficult to do output scheduling (FQ) • Output port • Easy to schedule packets on the link (FQ) • Fabric and OPP have to have high speedup.
Buffers • Our initial decision: • Buffer packets on the input port • Handle FQ at the input port (somehow) • Use standard SDRAM for buffers • PC-100 10ns access latency • Dimension buffer by simulation • Buffers for each input port.
Switch Scheduling • We will simulate with various scheduling mechanisms including Multicast schemes. • iSLIP, RR, FCFS etc • Virtual Output Queues to avoid HOL • Nominal Fabric speedup and priority classes. • Implement both Drop-tail and RED buffer schemes.
Switch Fabric • Shoot for 1024x1024 but backup is 64x64 • Vitesse VSC836 takes too long to configure!! • Use AMCC S2018 17x17 in a 3-stage CLOS network. • Other options?
Output Port Processing and scheduling • Basic de-framing and physical level processing. • FQ discipline • WFQ • W2FQ • How do we do this with input buffering?
Plan of Action • Decide on IPP and Network Processor. • Concentrate on switch fabric choice. • Analyze switch scheduling schemes. • Try to implement FQ with input port buffers. • Implement RED and Drop Tail. • Develop a simulator for the switch. • Experimentally determine the buffer size.