Instruction/ maintenance manual of the product IXP12xx Intel
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IXP12xx ATM OC12/Ethernet IP Router Example Design Performance and Headroom Analysis April, 2002 Document Number: 301144-001.
Version 1.0 , 4/10/02 Page 2 of 17 Information in this document is provided in connection with Intel products. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document.
Version 1.0 , 4/10/02 Page 3 of 17 IXP12xx ATM OC12/Ethernet IP Router Example Design Performance and Headroom Anal ysis OVERVIEW This documents details the performance and h eadroom analysis done on the IXP12xx ATM OC12 / Ethernet IP Router Example Design.
Version 1.0 , 4/10/02 Page 4 of 17 KEY WORKLOADS & APPROACHES TO TESTING THE EXAMPLE DESIGN Protocol Performance of IP over ATM vs. Ethernet Figure 1 details the protocol processing required to carry an IP packet over ATM and Ethernet.
Version 1.0 , 4/10/02 Page 5 of 17 The result is that ATM is significantly more effici ent 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).
Version 1.0 , 4/10/02 Page 6 of 17 As shown graphically in Figure 3, 622Mbps of single- cell-PDU input requires 622*(84/55) = 949 Mbps of Ethernet output.
Version 1.0 , 4/10/02 Page 7 of 17 bytes/minimum frame}. 84 bytes/frame * 8 bits/byte / 100Mb/sec = 6.72 usec/frame. 232MHz * 6.72 usec/frame = 1559 cycles/frame These cycle budgets specify how frequently a cell or frame goes over the wire. If multiple threads handle multiple frames on the same wire, then the budgets are multiplied accordingly.
Version 1.0 , 4/10/02 Page 8 of 17 One issue with running simulations unbounded to wi re-rate is that it can hide errors because there is no concept of device overflows or underflows.
Version 1.0 , 4/10/02 Page 9 of 17 Both the OC-12 and 4xOC-3 configurations experi ence an ATM overflow after 1M cycles. This indicates that under this system workload, the r eceiver is not keeping up with the wire, but has dropped a cell in the first 6,000 cells.
Version 1.0 , 4/10/02 Page 10 of 17 the number of times the PHY was not fed a cell in time to keep the wire busy, and thus had to manufacture an idle cell.
Version 1.0 , 4/10/02 Page 11 of 17 degrade in these scenarios, a nd the design becomes subject to ATM overflows from running “_VolgaGetChanCounters”. Ethernet Input Ports ATM Transmit Rate [%] IXF6012 Transmit Idle ATM Receive Ports IXF6012 Overflows Ethernet Transmit KFrame/s Ethernet Transmit [MB/s] 8 84 N/A 1 0 138 - 147 8.
Version 1.0 , 4/10/02 Page 12 of 17 Ethernet Input Ports ATM Transmit Rate [%] IXF6012 Transmit Idle ATM Receive Ports IXF6012 Overflows Ethernet Transmit KFrame/s Ethernet Transmit [MB/s] 8 100 0 1 0 88,300 5.
Version 1.0 , 4/10/02 Page 13 of 17 Queue to Core Measurement Technique The performance of the queue-to-core path can be measured by modifying a nominal input data stream such that the entire stream is forwarded to core. For example, changing the IP version in the IP header from 4 to 5 will cause the packets to be forwarded to the core.
Version 1.0 , 4/10/02 Page 14 of 17 RESOURCE UTILIZATION AND HEADROOM ANALYSIS This section details system resource utilization, including per-microengine resources such as registers and microstore instructions; as well as shared resources such as Scratchpad RAM, SRAM, and DRAM.
Version 1.0 , 4/10/02 Page 15 of 17 Microstore utilization can be observed by openi ng a microengine list window with line num bers enabled, and recording the last line number plus 1. A vailable instructions = 2048 – used instructions. Figure 12 shows the results for each of the three configurations.
Version 1.0 , 4/10/02 Page 16 of 17 SDRAM Capacity The IXM1240 Network Processor Base Card comes with 128MB of SDRAM. The project is configured to use less than 64MB: 32MB of Packet Data Buffers, 16MB for VxWorks, and the balance for IP Route Table Entries.
Version 1.0 , 4/10/02 Page 17 of 17 APPENDIX Buffer Allocation in DRAM The microengines in this example design uses two DRAM command queues. The ordered queue is used by all sdram_crc[] commands to transfer packet data between DRAM and the receive and transmit FIFOs.
An important point after buying a device Intel IXP12xx (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought Intel IXP12xx yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Intel IXP12xx - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Intel IXP12xx you will learn all the available features of the product, as well as information on its operation. The information that you get Intel IXP12xx will certainly help you make a decision on the purchase.
If you already are a holder of Intel IXP12xx, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Intel IXP12xx.
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