Box-to-Box Redundancy Configuration for Cisco Unified Border Element High Availability

BD.

Configure box-to-box redundancy when you:Expect the behavior of the CSSs to be active/standby (only the master CSS processes flows)Can configure a dedicated Fast Ethernet (FE) link between the CSSs for the VRRP heartbeat Do not configure box-to-box redundancy when you:Expect the behavior of the CSSs to be active-active (both CSSs processing flows)

Use VIP redundancy instead.Cannot configure a dedicated FE link between the CSSs.Require the connection of a Layer 2 device between the redundant CSS peers.

Before Cisco IOS release 15.2.3T, Cisco Unified Border Element (CUBE) high availability with box-to-box redundancy configuration had the following characteristics:

A. It leverages HSRP for router redundancy and GLBP for load sharing between a pair of routers. - This statement is incorrect. CUBE high availability with box-to-box redundancy does not use GLBP for load sharing between a pair of routers. Instead, it uses load sharing based on flow-based forwarding (FAF) or load-based forwarding (LBF) algorithms.

B. Cisco Unified Border Element session information is check-pointed across the active and standby router pair. - This statement is correct. CUBE high availability with box-to-box redundancy configuration checkpointed the CUBE session information across the active and standby router pair. Checkpointing allows session information to be preserved during a switchover to the standby router in case the active router fails.

C. It supports media and signal preservation when a switchover occurs. - This statement is correct. CUBE high availability with box-to-box redundancy configuration supports media and signal preservation when a switchover occurs. The standby router takes over the active router's role seamlessly without dropping or interrupting media and signal streams.

D. Only media streams are preserved when a switchover occurs. - This statement is incorrect. CUBE high availability with box-to-box redundancy configuration preserves both media and signal streams when a switchover occurs.

E. It can leverage either HSRP or VRRP for router redundancy. - This statement is incorrect. CUBE high availability with box-to-box redundancy configuration can only use HSRP for router redundancy.

F. The SIP media signal must be bound to the loopback interface. - This statement is incorrect. There is no requirement for the SIP media signal to be bound to the loopback interface in CUBE high availability with box-to-box redundancy configuration.

In summary, before Cisco IOS release 15.2.3T, CUBE high availability with box-to-box redundancy configuration checkpointed session information, supported media and signal preservation during a switchover, and could only use HSRP for router redundancy. It did not use GLBP for load sharing, and there was no requirement for the SIP media signal to be bound to the loopback interface.