First Published: July 13, 2016
DOCSIS 3.1 introduces the concept of downstream profiles for OFDM channels.
 Note |
The hardware components that are introduced in a given Cisco IOS-XE Release are supported in all subsequent releases unless otherwise specified. |
A profile is a list of modulation orders that are defined for each of the subcarriers within an OFDM channel. The CMTS can define multiple profiles for use in an OFDM channel, where the profiles differ in the modulation orders assigned to each subcarrier. The CMTS can assign different profiles for different groups of CMs.
Note |
Profile A, with profile ID 0, is also referred to as the control profile. |
Based on the Receive Modulation Error Ratio (RxMER) values collected from a modem, the CMTS finds among the existing profiles the one that may provide the highest speed, and yet at the same time may have sufficient Signal to Noise Ratio (SNR) margin for the modem to receive code words with acceptable error. This profile is called the recommended profile for that CM. The show cable modem phy ofdm-profile command displays the recommended profile for each CM. The CMTS does not automatically upgrade a CM's profile to the recommended profile. Recommended Profile will take effect when the CM is reset by the operator. When the CM comes back online, recommended profile is assigned to it.
Router (config)#cable downstream ofdm-prof-mgmt recommend-profile-age age-in-minutesWhen the CMTS receives CM-STATUS Event 16 (DS OFDM Profile Failure), the profile indicated in the CM-STATUS message is marked as 'unfit profile' for this modem.
Router (config)#cable downstream ofdm-prof-mgmt unfit-profile-age age-in-minutesRouter# show controllers integrated-Cable 2/0/3 rf-channel 158 prof-order|
Event Type |
Event Condition |
Status Report Events |
Parameters reported by CM |
||
|---|---|---|---|---|---|
|
Trigger event to "on" |
Trigger event to "off" |
DCID |
Profile ID |
||
|
16 |
DS OFDM profile failure |
Loss of FEC lock on one of the assigned downstream OFDM profiles of a channel |
Re-establishment of FEC lock for that OFDM profile; OR Removal of the channel from the active channel list in the primary channel MDD; OR Removal of the channel from the CM's Receive Channel set via DBC-REQ |
Yes |
Yes |
Router (config)#no cable downstream ofdm-prof-mgmt prof-dwngrd-auto|
RxMER (in ΒΌ DB) |
QAM |
Bit Loading |
|---|---|---|
|
60 |
16 |
4 |
|
84 |
64 |
6 |
|
96 |
128 |
7 |
|
108 |
256 |
8 |
|
122 |
512 |
9 |
|
136 |
1024 |
10 |
|
148 |
2048 |
11 |
|
164 |
4096 |
12 |
|
184 |
8192 |
13 |
|
208 |
16384 |
14 |
Router(config)# cable downstream ofdm-prof-mgmt mer-margin-qdb quarter-DBRouter(config)# cable downstream ofdm-prof-mgmt exempt-sc-pct percentCisco cBR supports Hitless OFDM Profile from Cisco IOS XE Everest 16.12.1x, as a Profile Management Application (PMA) tool.
The operation is as follows:
PMA determines if the modulation order of a data profile in an OFDM channel can be upgraded or downgraded. This decision is based on the MER data that is received from cable modems that uses the profile.
Poll cBR for all modems with active profiles to identify inactive ones.
Move modems to a temporary data profile if all are in use. Note that this is not control profile.
Delete any unused OFDM profile. The PMA repeats step 2 and step 3 to avoid race conditions.
Add (or Delete) a new OFDM profile with the desired modulation order to the OFDM channel.
Define the new profile list for the modems (DBC sent to modems by cBR).
Move modems to the new profile.
Cisco cBR supports Ephemeral Profile to Cable Modem Assignment from Cisco IOS XE Everest 16.12.1x, as a Profile Management Application (PMA) tool.
If the modem is not listening to the desired profile, you can submit up to 4 data profiles. The PMA wants to be active for that cable modem before issuing the profile assignment command. The control profile zero (0) is always included by default.
The following commands are supported:
cable modem <mac> ofdm-set-profiles chan <n> profiles <profile list>
This command initiates a DBC to the cable modem with the specified profile list. The profile list order defines the downgrade profile in case the CM-STATUS is 16.
cable downstream ofdm-flow-to-profile interface <integrated-Cable x/y/z:n> profile-data <n> mac- address <mac>
This command enables the CMTS to start forwarding all traffic to the cable modem using the specified profile. Ensure that you use the accompanying cable modem mac-address mac opt0 command for the changes to take effect immediately.
Move the cable modems traffic to one of the profiles that it is listening to. DBC is not necessary. If the profile is not active on the cable modem, then the CLI reports error. If the CMTS receives a CM-STATUS 16 for that profile, the CMTS downgrades the profile automatically.
The CM-STATUS does not reset when moving to another profile.
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Note |
The following table lists the software release in which a given feature is introduced. Unless noted otherwise, subsequent releases of that software release train also support that feature. |
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Feature Name |
Releases |
Feature Information |
|---|---|---|
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Downstream Profile Selection |
Cisco IOS XE Everest 16.6.1 |
This feature was integrated into Cisco IOS XE Everest 16.6.1 on the Cisco cBR Series Converged Broadband Routers. |
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