Cisco Cisco IOS Software Release 12.1(1a)T1 Manuel Technique
cable linecard.
Note: It is important to know that, before converting all your modems to two−way, you should carefully
select the upstream frequency (the example uses 24000000 MHz). Also, make sure the return path is available
and clean by using a spectrum analyzer. To learn how to measure the upstream, refer to Cable FAQ. When
performing a cut−over from Telco−Return to two−way, it is recommended to first try the cut−over with a few
cable modems inside the cable plant headend and a small sample out in the field. This can be done initially as
a test to check if there are any return path issues before rolling out the cut−over.
select the upstream frequency (the example uses 24000000 MHz). Also, make sure the return path is available
and clean by using a spectrum analyzer. To learn how to measure the upstream, refer to Cable FAQ. When
performing a cut−over from Telco−Return to two−way, it is recommended to first try the cut−over with a few
cable modems inside the cable plant headend and a small sample out in the field. This can be done initially as
a test to check if there are any return path issues before rolling out the cut−over.
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
This document uses these specific software and hardware versions:
uBR7223 with Cisco IOS® software 12.0(5)T
•
Cisco Network Registrar (CNR) version 3.5.3
•
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.
Example of a Mixed Telco−Return and Two−Way
Environment
Environment
This portion of a CMTS configuration shows the necessary commands that are relevant to Telco−Return.
interface Cable2/0
ip address 10.10.169.1 255.255.255.0 secondary
ip address 10.10.168.1 255.255.255.0
no ip directed−broadcast
cable helper−address 172.16.135.20
no ip route−cache
no ip mroute−cache
no keepalive
cable insertion−interval automatic 25 500
cable dhcp−giaddr policy
cable downstream annex B
cable downstream modulation 64qam
cable downstream interleave−depth 32
cable downstream frequency 117000000
cable upstream 0 frequency 24000000
cable upstream 0 power−level 0
cable upstream 0 range−backoff 0 6
no cable upstream 0 shutdown
cable Telco−Return enable
cable Telco−Return spd 1 factory−default
cable Telco−Return spd 1 threshold 255
cable Telco−Return spd 1 dial−timer 1200
cable Telco−Return spd 1 manual−dial
cable Telco−Return spd 1 dhcp−authenticate
cable Telco−Return spd 1 dhcp−server 172.16.135.20