Cisco UC: ISR box-to-box REDundancy

The Interchassis High Availability feature (box-to-box redundancy) enables the configuration of pairs of routers to act as backup for each other.

Failover: the standby router seamlessly takes over and starts processing call signaling and performing media forwarding tasks.

Note: failover causes reboot by design.

Configuration on ISR 4000 series

Enable CUBE and redundancy on both routers:

voice service voip 
  mode border-element
  allow-connections sip to sip

Configure an redundancy group with interface tracking – track the voice traffic interface state so that the Active router will initiate switchover after the traffic interface is down:

  • GigabitEthernet0/0/0 – the interface used for SIP trunk to CUCM
  • GigabitEthernet0/0/1 – the interface used for for SIP trunk to SIP Provider
  • GigabitEthernet0/0/2 – the interface used for checkpointing of data traffic between ISRs

NOTE: RG Control/Data Interfaces (Gi0/2) must be connected through a switch and not a Crossover cable.

track 1 interface GigabitEthernet0/0/0 line-protocol
track 2 interface GigabitEthernet0/0/1 line-protocol
track 3 interface GigabitEthernet0/0/2 line-protocol
!
redundancy
 mode none
 application redundancy
  group 1
   name VOICE
   priority 100 failover threshold 75
   timers delay 30 reload 60
   control GigabitEthernet0/0/2 protocol 1
   data GigabitEthernet0/0/2
   track 1 shutdown
   track 2 shutdown
   track 3 shutdown
  protocol 1
   timers hellotime 4 holdtime 6

Interface Configuration:

  • redundancy rii” (Redundant Interface Identifier) – used for generating a VMAC
  • group number should be the same
interface GigabitEthernet0/0/0
 description VOICE_INTERNAL
 ip vrf forwarding VOICE_INTERNAL
 ip address 10.10.10.101 255.255.255.0
 redundancy rii 1
 redundancy group 1 ip 10.10.10.100 exclusive 
!
interface GigabitEthernet0/0/1
 description VOICE_EXTERNAL
 ip vrf forwarding VOICE_EXTERNAL
 ip address 20.20.20.201 255.255.255.0
 redundancy rii 2
 redundancy group 1 ip 20.20.20.200 exclusive 
!
interface GigabitEthernet0/0/2
 description VOICE_XOVER
 ip address 192.168.15.15 255.255.255.0

Dial-Peers and SIP binding configuration:

dial-peer voice 100 voip
 description VOICE_EXTERNAL
 voice-class sip bind control source-interface GigabitEthernet0/0/1
 voice-class sip bind media source-interface GigabitEthernet0/0/1
!
dial-peer voice 200 voip
 description VOICE_INTERNAL
 voice-class sip bind control source-interface GigabitEthernet0/0/0
 voice-class sip bind media source-interface GigabitEthernet0/0/0

Enable CUBE redundancy and call check pointing on both routers:

voice service voip 
  redundancy-group 1
gateway 
 media-inactivity-criteria all
 timer receive-rtcp 5
 timer receive-rtp 86400

Reload the Router and configure another peer.
Point CUCM and SIP provider to the CUBE Virtual IP (VIP) Address.

Full Configuration for CUBE Box to Box Redundancy
voice service voip 
  mode border-element
  allow-connections sip to sip
  redundancy-group 1
!
redundancy
 mode none
 application redundancy
  group 1
   name VOICE
   priority 100 failover threshold 75
   timers delay 30 reload 60
   control GigabitEthernet0/0/2 protocol 1
   data GigabitEthernet0/0/2
   track 1 shutdown
   track 2 shutdown
   track 3 shutdown
  protocol 1
   timers hellotime 4 holdtime 6
!
track 1 interface GigabitEthernet0/0/0 line-protocol
track 2 interface GigabitEthernet0/0/1 line-protocol
track 3 interface GigabitEthernet0/0/2 line-protocol
!
!
interface GigabitEthernet0/0/0
 description VOICE_INTERNAL
 ip vrf forwarding VOICE_INTERNAL
 ip address 10.10.10.101 255.255.255.0
 redundancy rii 1
 redundancy group 1 ip 10.10.10.100 exclusive 
!
interface GigabitEthernet0/0/1
 description VOICE_EXTERNAL
 ip vrf forwarding VOICE_EXTERNAL
 ip address 20.20.20.201 255.255.255.0
 redundancy rii 2
 redundancy group 1 ip 20.20.20.200 exclusive 
!
interface GigabitEthernet0/0/2
 description VOICE_XOVER
 ip address 192.168.15.15 255.255.255.0
!
!
dial-peer voice 100 voip
 description VOICE_EXTERNAL
 voice-class sip bind control source-interface GigabitEthernet0/0/1
 voice-class sip bind media source-interface GigabitEthernet0/0/1
!
dial-peer voice 200 voip
 description VOICE_INTERNAL
 voice-class sip bind control source-interface GigabitEthernet0/0/0
 voice-class sip bind media source-interface GigabitEthernet0/0/0
!
gateway 
 media-inactivity-criteria all
 timer receive-rtcp 5
 timer receive-rtp 86400

Verification

sh redundancy application group all 

Status must be Active and Standby Hot:

Check VMAC and VIP:

cube1#sh redundancy application if-mgr group 

 RG ID: 1
 ==========

 interface      GigabitEthernet0/0/1
 ---------------------------------------
 VMAC           0077.b421.2222
 VIP            20.20.20.200
 Shut           no shut
 Decrement      0

 interface      GigabitEthernet0/0/0
 ---------------------------------------
 VMAC           0077.b421.1111
 VIP            10.10.10.100
 Shut           no shut
 Decrement      0

Testing

I made a call and it appears on both CUBEs:

CUBE1 is rebooted and CUBE2 becomes active with no call drop.

Administrative State: No Shutdown
Aggregate operational state : Up
My Role: ACTIVE
Peer Role: UNKNOWN
Peer Presence: No
Peer Comm: No
Peer Progression Started: No

RF Domain: btob-one
         RF state: ACTIVE
         Peer RF state: DISABLED
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