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I'm currently searching the performance of a Cisco router model ASR-1001-X. I know that the max throughput/backplane speed is 20G. I'm confuse of the Packet Per Second performance measurement from Cisco. Could anyone help to explain and how to find this? Does it depend on bandwidth? I see in some doc:

ASR1000-ESP20 PPS (Packet Per Second): 25,430,000 <=> 13,020.16 Mbps

thank you in advance for help.

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    This router type will forward not more than max. 16Mpps OR 20Gbps depending on what will be exceeded first. When you know your packet size, you can do some math like: 16.000 packets per second * 1500 bytes per packet = 24.000.000 bytes per second * 8 = 192.000.000 bps = ~180Mbps. That means in theory, with 1500 byte packets, you will only exceed max packets per second. – Markus Dec 4 '18 at 14:29
  • @Markus, I think Cisco's specifications for pps are using 64 byte packets. You can usually find that somewhere in the fine print. Most vendors use small packets for the pps rating. – Ron Maupin Dec 4 '18 at 16:21
  • Thank you all, @Markus taking the small packet as 64 bytes. I do the math and I find : 25430000 packets per second * 64 bytes * 8 = 13020160000bps =~ 13 Gbps (witch match the value above see somewhere in doc) – Mamitiana Ra Dec 5 '18 at 14:08
  • Is it "Up to 200-Gbps system throughput and up to 130 millions of packets per second (mpps) to address WAN aggregation needs" Note there are variant models with modules for 20 to 200 Gbit/sec throughput. cisco.com/c/en/us/products/collateral/routers/… – jonathanjo Dec 5 '18 at 15:09
  • @jonathanjo , In my case, it's a model with max of 20Gbit/sec throughput. thank you for the datasheet – Mamitiana Ra Dec 6 '18 at 6:05
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Networking products have all kinds of resources in them, and all of them have limits.

  • One of most interesting limits (for sales, anyways) is the maximum bandwidth that can go through it, under best conditions.
  • A second useful limit is how many packets per second, under best conditions

It can't do both of these at the same time. Its maximum throughput will be with large packets; its maximum packet processing will be with small packets. There's a performance curve which trades off the two measurements.

For analogy, the maximum speed of a bus might be 50 km/hour (when no traffic), the maximum passenger-journeys might be 6,000 journeys/hour (during rush hour). It doesn't do them at the same time.

  • Thank you, so the maximum bandwidth that I could send depends on the packet size lenght. For a standard packet sieze (~ 1500 bytes ), I can reach the Maximum troughput (in my case 20Gps) and just 13 Gbps (25,430,000 PPS) in case I send small packets (~ 64 bytes)? – Mamitiana Ra Dec 5 '18 at 14:01
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    Treat any anufacturer's performance figures with caution: they are going to be the best measurement under optimal conditions for each measurement. Further, they are often principally used for sales materials. There is no reason to think any actual client's situation will be optimal. Instead, if any of your likely requirements are near any of the limits, consider doing some benchmarking to see if the equipment will perform adequately under your real conditions. – jonathanjo Dec 5 '18 at 14:59
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    NB re "standard packet size" -- this would only be the case for TCP. If you put the router in front of a DNS farm, perhaps all you get are 100-200 byte UDP packets, and the principal metric of the router is transit time; or in front of VOIP servers, where you really care about QOS queueing. – jonathanjo Dec 5 '18 at 15:05

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