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Chapter 2
Cisco CMTS Configuration Commands
Table 2-9
Channel
Width (KHz)
200
400
800
1600
3200
For example, with a 3.2 MHz channel width and QPSK modulation, the total bandwidth is approximately
5 Mbps. This is the maximum allowable bandwidth that can be allocated to CMs at the default admission
rate of 100%. If each CM is allocated a minimum upstream bandwidth of 128 kbps, this means a
maximum of 40 CMs will be allowed to come online.
To verify whether or not upstream admission control is configured and activated, use the show interface
command for a cable upstream to display its configuration information. If upstream admission control
is configured and enabled, the output contains an entry stating "CIR admission control enforced." If
upstream admission control is disabled, no admission control entry is displayed in the output.
Setting the admission control limit to below the current total reserved bandwidth for the channel does
Note
not immediately force any CMs offline, but may prevent CMs from reconnecting if they drop offline at
a later time. Increasing the admission control limit allows more CMs to connect.
When an upstream becomes overbooked, use the test cable ucc command to move a cable modem that
is currently online from one upstream port to another. For example, the following example shows that
the cable modem with the IP address of 10.128.1.128 is being moved from port C3/0/U0 to C3/0/U1:
router# show cable modem 10.128.1.128
Interface
Cable3/0/U0 101
router# test cable ucc c3/0 101 1
router# show cable modem 10.128.1.128
Interface
Cable3/0/U1 101
Examples
The following example shows overbooking on upstream port 4 being limited to 125 percent:
Router(config)# interface cable 3/0
Router(config-if)# cable upstream 4 admission-control 125
Router(config-if)#
Use the
an interface. For example, the following command output shows that this upstream has allocated a total
bandwidth of 2.5 Mbit/sec to those online CMs that were assigned a guaranteed upstream bandwidth in
their DOCSIS configuration files.
OL-1581-08
Admission Control Bandwidth Table
Symbol Rate
QPSK Virtual Channel
(Ksym/sec)
Bandwidth—100% limit (bits/sec)
160
320,000
320
640,000
640
1,280,000
1280
2,560,000
2560
5,120,000
Prim Online
Timing Rec
Sid
State
Offset Power
online
1919
Prim Online
Timing Rec
Sid
State
Offset Power
online
1920
show interface cable upstream
QoS CPE IP address
5.25
7
0
10.128.1.128
QoS CPE IP address
5.25
7
0
10.128.1.128
command to display the current status of admission control on
Cisco Broadband Cable Command Reference Guide
cable upstream admission-control
16 QAM Virtual Channel
Bandwidth—100% limit (bits/sec)
640,000
1,280,000
2,560,000
5,120,000
10,240,000
MAC address
0030.1976.7067
MAC address
0030.1976.7067
2-287
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