Specifications

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Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
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Chapter 6 Cisco IGX 8400 Series Data Service
Data Service Provisioning
Enabling DFM on a Data Channel
Note DFM is a purchased feature. Contact your Cisco account representative for more information (see the
“Obtaining Technical Assistance” section on page xiv).
DFM on the IGX allows suppression of repetitive data patterns (such as idle codes) at the source node
and regeneration of the repetitive data pattern at the remote node, resulting in more efficient bandwidth
utilization. DFM is used automatically when enabled at both ends of the connection, for speeds up to
128 kbps. If DFM is not enabled, the connection will continue to generate packets for repetitive data
patterns.
To enable DFM, use the following procedure:
Step 1 Contact the Cisco Technical Assistance Center to activate the DFM feature on each applicable node (see
the “Obtaining Technical Assistance” section on page xiv).
When DFM is first activated, it defaults to enabled on each data channel with the following default
values:
• Percent of channel utilization is 100 percent
• Pattern length is 8 bits
• DFM status is enabled
Step 2 (Optional) Configure DFM using the switch software cnfchdfm command at both ends of the connection
to enable orderable DFM or to change the pattern length.
Enabling Embedded EIA on the LDM
The embedded EIA feature encodes the status of a single control lead as the eighth bit in each data byte.
The byte subsequently is processed in accordance with the DFM algorithm, which remains unchanged.
Any DCE and DTE combination at each end is valid. A typical configuration might have the LDP at one
end of a connection as DCE and an LDM at the other end as DTE. RTS is transmitted in encoded form
from the remote end to the local end, and CTS is transmitted in the other direction. Other control leads
use the noninterleaved format.
Note Embedded EIA is allowed for all legal baud rates up to 19.2 kbps.
To enable embedded EIA, activate embedded EIA for the data channel with the switch software addcon
local channel remote node remote channel 7/8E *Z command.
Note You can set up different channels on the same card with or without embedded EIA, but all ports on the
card must be configured at or below 19.2 kbps for embedded EIA to be active.