[netperf-talk] Packet size

[Clive Barker]

hi everyone, i am hitting another bump and this time, although i'm able to get something across, i continue to get the same error message while sending TCP streams across

any ideas please?

test1:~$ netperf -H 192.168.1.13 -p 4000 -t TCP_STREAM -- -m 128 -D   
recv_response: partial response received: 71 bytes

test1:~$ netperf -H 192.168.1.13 -p 4000 -t TCP_STREAM -- -m 512 -D
recv_response: partial response received: 71 bytes

test1:~$ netperf -H 192.168.1.13 -p 4000 -t TCP_STREAM -- -m 10000 -D
recv_response: partial response received: 71 bytes

test1:~$ netperf -H 192.168.1.13 -p 4000 -t TCP_STREAM -- -m 10000000 -D
recv_response: partial response received: 71 bytes

test1:~$ netperf -H 192.168.1.13 -p 4000 -t TCP_STREAM -- -m 10000000 -D
recv_response: partial response received: 71 bytes



--- On Thu, 3/26/09, Rick Jones <rick.jones2 at hp.com> wrote:
From: Rick Jones <rick.jones2 at hp.com>
Subject: Re: [netperf-talk] Packet size
To: echelon360 at yahoo.com
Cc: netperf-talk at netperf.org
Date: Thursday, March 26, 2009, 9:47 AM

Clive Barker wrote:
> Hello,
> 
> is there an option for me to send traffic and include a packet size, i
need to generate several instances of netperf and have 3 separate runs starting
from 512bytes, 256bytes then 128bytes.
> 
> is this possible?

Is
 this TCP or UDP?  For UDP, since each send is a UDP datagram, you have
direct control over the UDP datagram size with the test-specific -m option:

netperf -H <remote> -t UDP_STREAM -- -m 128

will have a stream of UDP datagrams with 128 byte user payloads, added to that
will be 8 bytes of UDP header, 20 bytes (typically) of IPv4 header (or N bytes
of IPv6 header) and then M bytes of data-link header (14 for Ethernet).

If this is TCP, you have _indirect_ control over the quantity of data in each
TCP segment with a combination of the -m and -D (TCP_NODELAY):

netperf -H <remote> -t TCP_STREAM -- -m 128 -D

will *ask* TCP to not bundle-up successive sends into larger TCP segments.  So,
barring packet losses and retransmissions that will be 128 bytes of user payload
per segment, with 32 bytes (I'm including TCP timestamp option, 20 without
it) of TCP header, and then IP and data-link headers
 as with UDP.

Keep in mind that while 128, 256 and 512 bytes are usually smaller than a link
MTU, they don't _have_ to be, and so you could have either IP fragmentation
in the UDP case or TCP segmentation.

Now, if you mean you wanted a *mix* of packet sizes in the same
stream/flow/connection, that is something else, and is presently addressed in
netperf4, the egg-laying-woolly-milk-pig :) netperf.

rick jones



      
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