Endace DAG 7.1S, User Manual

Page: 34 / 51

EDM 01-17 DAG 7.1S Card User Guide
Increasing Buffer Size
You can increase the size of the host PC buffer to enable it to cope with
bursts of high traffic load on the network link.
By default the
dagmem
driver reserves 32MB of memory per DAG card in
the system. However if you are capturing at OC-12/STM-4 (622Mbps)
rates or above, you may require a larger buffer.
For Linux/BSD 128MB or more is recommended. However you can
change the amount of reserved memory by editing the file
/etc/modules
as follows
# For DAG 3.x, default 32MB/card
dagmem
#
# For DAG 4.x or 6.x, use more memory per card, E.G.
# dagmem dsize=128m
For Windows the upper limit is 32MB. This is usually sufficient however if
you do need to increase the amount of reserved memory please contact
Endace customer support at
support@endace.com for more information
The
dsize
option sets the amount of memory used per DAG card in the
system.
Note: The value of
dsize
multiplied by the number of DAG cards in the
system must be less than the amount of physical memory installed, as well
as less than 890MB.
Transmitting
The DAG 7.1S is able to transmit as well as receive packets and it is
possible to . However the DAG card does not appear as a network interface
to the operating system.
It is possible to capture received traffic while also transmitting. You can
use capture tools such as
dagsnap
,
dagconvert
, and
dagbits
while
dagflood
is sending packets.
Version 2: May 2006 28 ©2006