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mess - packet_loss evaluation utility for IP-multicast.
mess [-h]
mess [-rdP] [-g group] [-c count] [-u upper_size] [-s size] [-v volume
per day] [-w wait_time]
The mess utility implements a sender and a receiver for IP-multicast
packets in order to help evaluating packet loss in a multicast backbone.
When acting as a sender (default mode of operation), the utility sends
count UDP packets filled with data to a multicast group and a selected
port. When acting as a receiver ( -r option), mess will wait for packets
on a selected port in a selected group. When interrupted, it displays the
number of packets and bytes received since start.
The options have the following meaning:
- -h
- Display a one line help and exit. This is mostly to be able to remember
the various options.
- -r
- Act as a receiver instead of being the sender of packets. This issues
a membership to the selected multicast group. You can verify
this membership by issuing the netstat -nia command ( netstat -g
under Solaris 2). Mess also writes it's pid to the file
/tmp/mess.pid. This can be used to stop a receiver that has no tty
associated by issuing kill -INT `cat /tmp/mess.pid`
- -d
- Debug mode. Shows the sizes of each received packet when acting as
a receiver.
- -g group
-
Specifies the multicast group a packet should be send to or of
which the host should become a member.
- -p port
-
Specifies the UDP port packets should be sent to or on which packets
should be attended.
- -c count
-
Sets the number of packets that are sent. With the option -u this
is the count per packet size.
- -u upper_size
-
This defines a upper packet size that is in some magical ;-) way
computed. There will be count packets be sent for each size until
that upper size is reached. Optional sizes are actually from 0 to
3 (note these are not bytes). -u is mutual exclusive with -s.
- -s size
-
This option overrides the -u option. The -s option specifies that
packets of size (+10) bytes are sent. So packets are at least 10
Bytes in size. This is to study the effects of fragmentation on
multicasting. It neither -u nor -s is given then -s is in effect.
- -V volume per day
-
This option is to specify the volume per day that should be sent
out; it is used to calculate the delay between packets to simulate
the load a news server produces. Unit of measurement are megabytes.
- -w wait_time
-
If running in receiver mode, this flag specifies a timeout given in
minutes that should be waited for packets. When the timeout is
over, mess terminates. This option is to allow starting the receiver
periodically from cron and terminating it after some time.
Without this option, mess runs until it is interrupted.
When errors occur, then mess prints a error message on stderr and exits.
-INT Kills the process. When acting as a receiver, a summary line is
printed that shows the number of received packets and bytes.
mess -g 225.1.2.3 -p 40000 -c 10 -s 990 sends 10 packets to the UDP port
40000. Packets are sent to the multicast group 225.1.2.3 and are 1000
bytes in size.
netstat(1)
, tcpdump(8)
, sysstat(8)
, udp(4)
, mrouted(8)
, mtrace(8)
,
cron(8)
, crontab(1)
The mess command is part of the diploma thesis Transport of NetNews via
IP-multicast
Heiko W.Rupp (hwr@pilhuhn.de)
The use of -u option is a bit ill.
Table of Contents
$Id: mess.1.html,v 1.5 2001/11/22 10:24:37 pilhuhn Exp $