Intel IXP12xx manual Frame and PDU Length versus IP Packet Length

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Version 1.0, 4/10/02

The result is that ATM is significantly more efficient that Ethernet in terms of Mbps for carrying very small PDUs. Every Mbps of single-cell-PDUs on the ATM link requires (84/55) Mbps on the matching Ethernet link(s).

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Figure 2 – Frame and PDU Length versus IP Packet Length

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OC- 12 Input OC- 3 Input

Figure 3 – Expected Ethernet Transmit Bandwidth

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Contents IXP12xx ATM OC12/Ethernet IP Router Example Design Version 1.0, 4/10/02 Alternate Dram Timing OverviewMeasurement Environment Single Cell PDU Workload KEY Workloads & Approaches to Testing the Example DesignProtocol Performance of IP over ATM vs. Ethernet Frame and PDU Length versus IP Packet Length Cycle and Instruction Budgets Multiple Cells/PDU WorkloadCycle Budgets to support Line Rates Cycles/cellCells/PDU Virtual Circuits Cycles/Cell Cycles/cell -7E Usec/frame = 1559 cycles/frameSimulated 29-byte packet performance1 Simulation Measurement Procedure and ResultsHardware Measurement Results Hardware Measurement Procedure and ResultsSimulated 40-byte and 1500-byte packet performance2 Hardware 29-byte packet performance Single-cell/PDU Performance using 133MHZ Dram138 142 144 Hardware 40-byte packet performance9.5 88,300517 Hardware 1500-byte packet performance518 Ethernet Queue to Core Throughput Queue to Core Measurement TechniqueATM Queue to Core Throughput Microengine Register and Microstore Headroom Resource Utilization and Headroom AnalysisSram Capacity Scratchpad RAM CapacitySram and Sdram Bandwidth Sdram CapacityBuffer Allocation in Dram Appendix