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 27
txrxerror
Indicates how to process packets that are transmitted with an RX error flag. Packets are
either discarded
(notxrxerror) on
or transmitted
(txrxerror).
Example
dagconfig txrxerror
dagconfig notxrxerror
varlen/novarlen
The DAG 7.5G4 card is able to capture packets in two ways. They are:
•
Variable length capture (
varlen
)
• Fixed length capture (
novarlen
) - (not support on some firmware images)
In
variable length
(
varlen
) mode, the DAG card will capture the whole packet, providing its
size is less than the
slen
value. Therefore to use this capture mode effectively you should set
the
slen
value to the largest number of bytes that a captured packet is likely to contain. For
more information on snaplength, see slen 25 (page ).
Any packet that is larger than the
slen
value will be truncated to that size. Any packet that is
smaller than the
slen
value will be captured at its actual size therefore producing a shorter
record which saves bandwidth and storage space.
Example
The example below shows a configuration for variable length full packet capture:
dagconfig -d0 varlen
In fixed length (
novarlen
) mode the card will capture all packets at the same length. Any
packet that is longer than the
slen
value will be truncated to that size, in the same way as for
varlen
capture. However any packet that is shorter than the
slen
value will be captured at its
full size and then padded out to the size of the
slen
value.
This means that in
novarlen
mode you should avoid large
slen
values because short packets
arriving will produce records with a large amount of padding which wastes bandwidth and
storage space.
Note:
Using the
novarlen
option on DAG cards with an on-board Co-Processor
(accelerated cards) is not recommended. It may cause excessive loss of packets.
Version information
Details the following information about the connected DAG card:
• Firmware image programmed in the FPGA
•
The DAG card serial number
•
The MAC address(s) of the DAG card's ports (ethernet cards only).