Ok 256 is including UDP, CRC. I think I know what's going on
I sending 256 bytes UDP packet ,
-4 bytes CRC
-14 bytes Ethernet header
give us 238 which is correct.
Does it make sense ??
Thanks a lot for you help !
From: Martin van den Nieuwelaar [mailto:firstname.lastname@example.org]
Sent: Saturday, August 11, 2001 3:37 PM
To: Aleks Sheynkman
Subject: Re: Netflow output question. Please help
Aleks Sheynkman wrote:
> Hello !
> I have small problem with the Netflow, I'm trying to send 100 UDP
> through the routers and see what will come out of
> Netflow, each packet is 256 bytes, so in the Netflow, I suppose to
> to see 25,600 bytes sent trough the interface ,
> but in some reason I always getting 23,800 bytes but number of packets
> Netflow reports as a 100 .
> Any idea?
The byte count reported by Netflow exports is supposed to be the
number of layer 3 (IP) payload bytes. Above, and in your other post
it isn't clear to me whether your IP data size is 256 bytes, or
whether your UDP data size is 256 bytes (indicating an IP data size of
256+8 for the UDP header = 264 bytes of IP data). Still, in any case
these should result in more than 23800 bytes being measured.
How about trying just one packet, and see if you get 238 bytes
measured? This might enlighten us as to whether an incorrect number
of bytes for each packet is being recorded, or maybe an incorrect
number of packets. (Still, the latter seems unlikely as 23800 doesn't
divide nicely by either 256 or 264...)
Lastly, are you _sure_ you're not sending 238 bytes of layer 3 data?
> Here is my configuration :
> Gig in |=============| POS OC3 out
> OC3 in |=============| Gig OUT
> ========= | Router A |
> =============================== | Router B | =====================
> Thanks a lot in advance !
> cflowd mailing list
-- Expert carrier network traffic analysis and visualisation http://www.gadgets.co.nz/products.shtml xenaphobia: The fear of being beaten to a pulp by a leather-clad, New Zealand woman -- cflowd mailing list email@example.com
This archive was generated by hypermail 2b29 : Sat Aug 11 2001 - 15:54:27 PDT