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Chieh Yu
Cisco Employee
Cisco Employee

Cable Technology

Global N+1 HCCP for CMTS Redundancy Configuration Guide

TAC Carrier Services 11/25/2007


Provide configuration example and assistance for Global 4+1 Redundancy on CMTS


IOS 12.3(13a)BC or Better UBR10k2 with ESR-PRE2 Up to 7x UBR-MC5X20x-D Line card in slot other than slot 5/1 as "Working" UBR-MC5X20x-D Line card in slot 5/1 as "Protect"  Up to 2x RF-Switch


For complete reference please consult the Cisco N+1 Feature Guide [1]. The scope of this guide is intended to give the reader a general overview of N+1 configuration setup in our SJC TAC labs.

N+1 Global redundancy refers to the high availability feature of the CMTS which allows for one standby cable line card to protect up to seven production cable line cards. The cable line cards are connected to one (for 4+1) or two (for 7+1) RF-Switches. The RF-Switch is a hardware switch which switches a problematic cable line card’s connectors over to the protect card. The failover process is extremely quick and is theoretically low impact.


CMTS Slot 7/0 -> RF Switch Slot 3
CMTS Slot 5/1 -> RF Switch Protect *P2 Column*
RF Switch Slot 3 to Plant

Verification & Troubleshooting:


show hccp {brief|...}
test hccp rfswitch {poll|relay}
redundancy linecard-group switchover from 7/0     <- "Make this working switch to protect..."
redundancy linecard-group revertback 7/0     <- "Take off protect back onto this working..."
show redundancy linecard all              
telnet x.x.x. /noecho                    <- Telneting into rfswitch with noecho option


show config
set snmp community COMMUNITY
set snmp host IP_ADDR
set snmp trap
test module

Here is a sample of known working lab ubr10k:

  auto-sync standard
linecard-group 1 cable
  rf-switch protection-mode 4+1
  member subslot 5/1 protect
  member subslot 7/0 working
ip host rfsw-1
! If 8+1
! ip host rfsw-2 x.x.x.x
snmp-server community private view hccp_chansw_snmp_view RW   
! Cable 7/0 interface configuration snippet
cable downstream annex B
cable downstream modulation 256qam
cable downstream interleave-depth 32
cable downstream frequency 609000000

RF Switch:

IP addr:
Subnet mask:
MAC addr: 00-03-8F-01-04-05
Gateway IP:
TFTP host IP: none
ARP timeout: 14400 secs
DHCP lease time: infinite
TELNET inactivity timeout: 600 secs
Password: (none)
SNMP Community: tac
SNMP Traps: Disabled
SNMP Trap Interval: 300 sec(s)
SNMP Trap Hosts: none
Card Protect Mode: 4+1
Protect Mode Reset: Disabled
Slot Config: 0x03ff 0x1c00 (13 cards)
Watchdog Timeout: 20 sec(s)
Group definitions: 4
  ALL        0xffffffff
  GRP1       0xaa200000
  GRP2       0x55100000
  GRP3       0xfc200000


[1] Cisco Global N+1 Redundancy Guide

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