Comtech EF Data CDM-625A Installation And Operation Manual page 276

CDM-625A Advanced Satellite Modem
Ethernet-based Remote Product Management
ASFD Bandwidth Mode – Use the drop-down list to select Datarate or Percentage:
• In the default Datarate mode, the minimum bandwidths for all Assured Forwarding Classes
are those that are specified in the Service Rate (Kbps) column.
• In Percentage mode, the minimum bandwidths for all Assured Forwarding Classes are
calculated (as a percentage of modems current TX data rate) using values that are specified
in the Service Rate (%) column.
For the Differentiated Services tabulature – From left to right, note the following:
Column
Priority
Per-Hop Behavior (PHB)
Codepoint (DSCP)
The user has the option of configuring each queue to one of the following attributes (the
acceptable ranges are shown in brackets):
Column
Service Rate (kbps)
Service Rate (%)
Drop Preferences
Click [Submit] to save.
Description
IP traffic is prioritized based upon the DSCP (DiffServ Code Points) Class Selector
Precedence.
Traffic class that determines how packets will be forwarded.
Codepoint value in Type of Service (ToS) byte in IP header.
Description
[ -0.000 / (Tx Data Rate)] This field is active when the ASFD Bandwidth Mode is set
to Datarate.The minimum bandwidth will be served first among the Assured
Forwarding (ASFD) classes in case of bandwidth availability once Class Selector 7
through Class Selected 1 have been serviced.
This field is active when the ASFD Bandwidth Mode is set to Percentage.This
column is for specifying the minimum service rates (for the Assured Forwarding
Classes) as a percentage of modem's current Tx data rate. These minimums are
served in case of bandwidth availability once Class Selector 7 through Class
Selector 1 has been serviced. This is very handy for ACM links where the modem
Tx data rate varies.
ASFD Class 4 through 1 Code Points (b100xx0, b011xx0, b010xx0, and b001xx0)
carry the drop precedence value (xx). In case of network congestion, a Weighted
Random Early Detection (WRED) congestion avoidance algorithm is imposed on
these queues to drop the packets randomly rather than 'tail drop.'
Low Drop Precedence (% full) [0–100] – In case of congestion, the WRED
•
is applied after the queue depth exceeds the configured percentage value
assigned for the Drop Precedence value b001.
Med. Drop Precedence (% full) [0–99] – In case of congestion, the WRED
•
is applied after the queue depth exceeds the configured percentage value
assigned for the Drop Precedence value b010.
High Drop Precedence (% full)) [0–99] – In case of congestion, the WRED
•
is applied after the queue depth exceeds the configured percentage value
assigned for the Drop Precedence value b011.
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MN-CDM625A
Revision 4