Endace DAG 5.2X, Руководство пользователя

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EDM01-33v1 DAG_7.5G4_Card_User_Guide
©2008 Endace Technology Ltd. Confidential - Version 1 - November 2008 39
Explicit Packet Transmission
The operating system does not recognize the DAG 7.5G4 card as a network interface and will
not respond to ARP, ping, or router discovery protocols.
The DAG 7.5G4 card will only transmit packets that are explicitly provided by the user. This
allows you to use the DAG 7.5G4 card as a simple traffic load generator.
You can also use it to retransmit previously recorded packet traces. The packet trace is
transmitted as fast as possible. The packet timing of the original trace file is not reproduced.
Trace Files
You can use
dagflood
to transmit ERF format trace files, providing the files contain only ERF
records of the type matching the current link configuration.
When you use DAG cards with multiple ports, ensure all ports referred to by the Trace file
are active. This ensures the
dagflood
traffic is not blocked when trying to delivering data to
an inactive port. Check the interface status output for the DAG card and ensure the link
status for all required destination ports is active. See Viewing the DAG card statistics.
29
(page
)
For further information on using
dagflood
please refer to the
EDM04-03 dagflood User Manual
available from Endace Customer Support at https://www.endace.com/support
If packets have been captured without using the
align64
option you can convert the trace
files so that they can be transmitted by using
.
In addition the length of the ERF records to be transmitted must be a multiple of 64-bits. You
can configure this when capturing packets for later transmission by setting 64-bit alignment
using the
dagconfig align64
command.
dagconvert 37 (page ) as shown below:
dagconvert -v -i tracefile.erf -o tracefile.erf -A8
Alternatively if you are unsure if a trace file is 64-bit aligned you can test the file using
dagbits 34 (page ) as shown below:
dagbits -v align64 -f tracefile.erf
If you do not have any ERF trace files available, you can use
daggen
to generate trace files
containing simple traffic patterns. This allows the DAG 7.5G4 card to be used as a test traffic
generator.
For further information on using
daggen
please refer to the EDM04-06 Daggen User Guide
available from Endace Customer Support at https://www.endace.com/support
TR TERF
.
Selectable CRC Length
TR-TERF can be optionally configured to strip the CRC of an incoming ERF stream, to allow
the retransmitted stream to calculate and add a CRC. There are three basic situations where
this option may be useful.
Situation 1
The ERF stream was generated without a CRC.
In this case, you should configure TR-TERF to
not strip the 32-bit CRC and configure the
MAC to add a hardware-calculated CRC. This has the effect of reducing the burden of
calculating a CRC in the software.
Example
dagconfig noterf_strip tx_crc