On Mon, Jul 07, 2008 at 10:30:53PM +1000, Bruce Evans wrote: > On Mon, 7 Jul 2008, Andre Oppermann wrote: > > > Bruce Evans wrote: > >> What are the other overheads? I calculate 1.644Mpps counting the > >> inter-frame > >> gap, with 64-byte packets and 64-header_size payloads. If the 64 bytes > >> is for the payload, then the max is much lower. > > > > The theoretical maximum at 64byte frames is 1,488,100. I've looked > > up my notes the 1.244Mpps number can be ajusted to 1.488Mpps. > > Where is the extra? I still get 1.644736 Mpps (10^9/(8*64+96)). > 1.488095 is for 64 bits extra (10^9/(8*64+96+64)).
A standard ethernet frame (on the wire) consists of: 7 octets preamble 1 octet Start Frame Delimiter 6 octets destination address 6 octets source address 2 octets length/type 46-1500 octets data (+padding if needed) 4 octets Frame Check Sequence Followed by (at least) 96 bits interFrameGap, before the next frame starts. For minimal packet size this gives a maximum packet rate at 1Gbit/s of 1e9/((7+1+6+6+2+46+4)*8+96)/ = 1488095 packets/second You probably missed the preamble and start frame delimiter in your calculation. -- <Insert your favourite quote here.> Erik Trulsson [EMAIL PROTECTED] _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
