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Cisco Broadband Cable Command Reference Guide
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Chapter 2 Cisco CMTS Configuration Commands
cable upstream admission-control
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.
Note
Setting the admission control limit to below the current total reserved bandwidth for the channel does
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 Prim Online Timing Rec QoS CPE IP address MAC address
Sid State Offset Power
Cable3/0/U0 101 online 1919 5.25 7 0 10.128.1.128 0030.1976.7067
router#
test cable ucc c3/0 101 1
router#
show cable modem 10.128.1.128
Interface Prim Online Timing Rec QoS CPE IP address MAC address
Sid State Offset Power
Cable3/0/U1 101 online 1920 5.25 7 0 10.128.1.128 0030.1976.7067
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
show interface cable upstream
command to display the current status of admission control on
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.
Table 2-9
Admission Control Bandwidth Table
Channel
Width (KHz)
Symbol Rate
(Ksym/sec)
QPSK Virtual Channel
Bandwidth—100% limit (bits/sec)
16 QAM Virtual Channel
Bandwidth—100% limit (bits/sec)
200
160
320,000
640,000
400
320
640,000
1,280,000
800
640
1,280,000
2,560,000
1600
1280
2,560,000
5,120,000
3200
2560
5,120,000
10,240,000