|
|
This feature provides configuration commands that allow you to create downstream test signals. Both Pseudo Random Bit Stream (PRBS), and unmodulated carrier test signals are now supported.
A PRBS test signal is a random data pattern that has been modulated to look like a real data stream. An unmodulated test signal is a continuous sine wave that looks like a carrier wave on the downstream transmission.
You can now create PRBS and unmodulated carrier tests directly. With earlier releases of IOS, you had to use test commands or indirect methods to perform these tests.
Table 1 lists the IOS cable router features released in the IOS 12.0 timeframe.
| Available With: | Category | Feature |
|---|---|---|
11.3(5)NA & 12.0(3)T | Cable Features | Feature Enhancements |
11.3(6)NA |
| MC16 Modem Card |
11.3(8)NA |
| Access List Support Enhancements |
12.0(4)T |
| Downstream Channel ID Configuration |
12.0(4)T |
| Multiple Service ID Support |
12.0(4)T |
| Cable Modem and Host Subnet Addressing |
12.0(5)T |
| Telephone Return |
12.0(5)T |
| Time Server Functionality |
12.0(7)T |
| Amplitude Averaging Compensation |
12.0(7)XR |
| Cable Interface Bundling |
12.0(7)XR |
| Enhanced Modem Status Display |
12.0(7)XR |
| Show Interface Cable Command Verbose Enhancements |
12.0(7)XR |
| IP Address Verification |
12.0(7)XR |
| Registration Timeout Configuration |
12.0(7)XR |
| Show Cable Modem Command Enhancements |
12.0(7)XR |
| Modem Status Summary Enhancements |
12.0(7)XR |
| Show Controller Command Enhancements |
12.0(7)XR |
| Configuring Concatenation |
12.0(7)XR |
| Virtual Private Network Support |
12.0(7)XR |
| Blind Hopping Support on the MC16S Modem Card |
12.0(7)XR |
| Signal-to-Noise Ratio Data Support |
11.3(9)NA and 12.0(4)T | Cable QoS | QoS Profile Enforcement |
12.0(4)T |
| Quality of Service for Voice |
11.3(9)NA | Network Management | Upstream Traffic Shaping Feature |
12.0(5)T |
| Enhanced-Spectrum Management |
12.0(5)T |
| Downstream Rate Shaping with TOS bits |
12.0(7)XR |
| Spectrum Management Using the MC16S Modem Card |
12.0(7)XR |
| Downstream Test Signals Configuration |
12.0(7)XR | Wireless Features | Point-to-Point Wireless Support |
The uBR7200 series cable router is described in Voice, Video, and Home Applications Configuration Guide for Cisco IOS Release 12.0 and in the following online feature modules:
uBR7200 series
No new or modified standards are supported by this feature.
No new or modified MIBs are supported by this feature.
No new or modified RFCs are supported by this feature.
See the following tasks to create PRBS and unmodulated carrier test signals. Each task in the list indicates if the task is optional or required.
| Step | Command | Purpose | ||
|---|---|---|---|---|
| # router(config-if)# cable downstream if-output continuous-wave | Generates an unmodulated continuous-wave signal on the downstream channel. The interface is shut down. | ||
| Router(config-if)# no cable downstream if-output | Stops sending test signals. Remember to re-enable the interface to resume normal operations. |
| Step | Command | Purpose | ||
|---|---|---|---|---|
| # router(config-if)# cable downstream if-output prbs | Generates a PRBS test signal on the downstream channel. The interface is shut down. | ||
| Router(config-if)# no cable downstream if-output | Stops sending test signals. Remember to re-enable the interface to resume normal operations. |
Step 1 To verify the output of a continuous-wave test signal, use a spectrum analyzer on the downstream channel.
Step 2 To verify the output of a PRBS test signal, use a spectrum analyzer on the downstream channel.
None
To create downstream test signals, use the cable downstream if-output interface configuration command. To stop sending test signals, use the no form of this command.
cable downstream if-output [continuous-wave | prbs]
continuous-wave | Creates a downstream unmodulated carrier signal. |
prbs | Creates a downstream PRBS carrier signal. |
Downstream carrier enabled.
Interface configuration
| Release | Modification |
|---|---|
11.3XA | This command was introduced. |
12.0(7)XR | continuous-wave and prbs options added. |
The standard mode of operation is modulated signal output and the interface is active. For PRBS and continuous wave output, the selected interface will be shut down. The functioning of the no cable downstream if-output command has not changed (the interface is shut down).
router(config-if)# cable downstream if-output continuous-wave router(config-if)# cable downstream if-output prbs
Posted: Fri Jan 21 21:35:00 PST 2000
Copyright 1989 - 2000©Cisco Systems Inc.