Subject: Re: the maximal speed of pktgen with 1Gbps NIC

From: Bob Gilligan <[email-masked]>
Date: Wed, 22 Jul 2009 10:12:17 -0700

Ben Hutchings wrote:
> On Wed, 2009-07-22 at 14:56 +0200, Jesper Dangaard Brouer wrote:
>> On Wed, 22 Jul 2009, [email-masked] wrote:
>>
>>> anyone knows the maximal speed of pktgen with 1Gbps NIC?
>> You are limited by the number of packets per second (pps) your machine can 
>> generate.  This limitation is given by the CPU speed and the NIC used.
>>
>> The maximum pps I have seen with pktgen at 1Gbit/s is 1200 kpps.
>>
>> 1Gbit/s wire speed pps with 64 bytes packets is approx 1953 kpps.
>> (1000*10^6/(64*8) = 1953125)
> [...]
> 
> You need to take the inter-packet gap into consideration too.

Yes.  Usually when people talk about the "64-byte PPS rate" they are 
referring to the maximum rate of minimum size ethernet frames.  The 
64-bytes includes the src/dst addr fields, type field and CRC, but does 
not include the preamble (7 bytes), SOF (1 byte) or IPG (12 bytes). 
Adding these in  gives a minimum size frame of 84 bytes.  This works out 
to a max rate of ( 1,000,000,000 / (84 * 8) ) = 1,488,095 PPS.

Bob.