Cisco MDS 9000 Installation And Configuration Note page 8

Selecting Truncate Mode
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m .
Table 2
Switch 1
ON
OFF
The speed does not matter (1 or 2 Gbps) if you place a switch in MNM mode.
Note
Configuring a combination of DIP settings, other than those mentioned in
Caution
unpredictable consequences.
Truncate Mode
If you want to use truncate mode, you need the DS-PAA-2. DS-PAA does not support this.
The Cisco Traffic Analyzer's Fibre Channel throughput values are not accurate when used with the
DS-PAA if data truncate is enabled. The DS-PAA-2 is required to achieve accurate results with truncate
because it adds a count that enables the Cisco Traffic Analyzer to determine how many data bytes were
actually transferred. By truncating a frame, you can push more packets through the PAA (2 Gbps for
Fibre Channel to 1 Gbps or slower for Ethernet) and preserve privacy of the traffic being captured.
Selecting Truncate Mode
Truncate mode is available in DS-PAA version 2 and later.
Note
Table 3
Channel frame and the Fibre Channel-to-Ethernet speed. For example, with a 2164-byte Fibre Channel
frame size, 1-Gbps Fibre Channel speed, and 100-Mbps Ethernet speed, you would select DTM mode.
Table 3
Average Size of the FC Frame
2164 bytes (best case to obtain
maximum data)
1496 bytes
Cisco MDS 9000 Family Port Analyzer Adapter Installation and Configuration Note
8
DIP Switch Settings and Modes of Operation (continued)
Switch 2 Switch 3
OFF OFF
OFF OFF
shows an example of how to select the truncate mode according to the average size of the Fibre
Selecting the Truncate Mode to Achieve No Dropped Frames
Fibre Channel
Switch 4 Mode
OFF 2 Gbps
OFF 2 Gbps
Fibre Channel to Ethernet Speed
1 Gbps to 1 Gbps to
1 Gbps 100 Mbps
NTM, ETM, DTM
STM, or DTM
NTM, ETM, DTM
STM, or DTM
Operating
Mode
ETM
NTM
Table 2, may have
2 Gbps to 2 Gbps to
1 Gbps 100 Mbps
DTM or STM DTM
DTM or STM Frames may be
dropped.
OL-9077-01