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Cisco Broadband Cable Command Reference Guide
OL-1581-08
Chapter 2 Cisco CMTS Configuration Commands
cable map-advance
cable map-advance
To configure the dynamic map advance algorithm, use the
cable map-advance
command in cable
interface configuration mode. Use the
no
form of this command to disable this function.
cable map-advance
[
dynamic
[
safety
] |
static
]
[
max-delay
]
no cable map-advance
Syntax Description
Defaults
Dynamic map advance with a
safety
factor of 1000 microseconds and a
max-delay
of 1800 microseconds
Command Modes
Interface configuration (cable interface only)
Command History
dynamic
safety
Enables the dynamic MAP advance algorithm that automatically tunes
lookahead time in MAPs based on the current farthest CM on a
particular upstream port. The
safety
argument specifies a safety factor
for the dynamic map advance algorithm in microseconds. This value
controls the amount of extra lookahead time in MAPs to account for
inaccuracies of the measurement system and internal software
latencies. The valid range is 300 to 1500 microseconds, with a default
of 1000.
Note
Using larger safety factors increases the run time lookahead in
MAPs, but reduces the upstream performance.
static
Enables the static map advance algorithm that uses a fixed lookahead
time value in MAPs based on the worst-case propagation delay of 100
mile HFC cable network.
max-delay
Specifies the maximum round trip delay between the cable plant and
furthest CM in microseconds. The valid range is 100 to 2000
microseconds, with a default of 1800. The typical delay for a mile of
coaxial cable is approximately 7 microseconds. The typical delay for a
mile of fiber cable is approximately 8 microseconds.
Release
Modification
12.1T
This command was introduced.
12.0 (9)SC, 12.1(2)EC1 The
dynamic
option was added.
12.1(10)EC
The
max-delay
option was added. The dynamic MAP algorithm was also
enhanced so that it can quickly determine whether the furthest CM is now
offline, so that the MAP advance algorithm can be updated accordingly.
12.2(8)BC1
The range for the
max-delay
option was changed to the current values of
between 100 and 2000 microseconds.
