Which two statements are true about a unified ISSU? (Choose two.)
A . It requires that Bidirectional Forwarding Detection be disabled.
B . It is only supported on platforms with redundant control planes.
C . It is only supported on platforms with redundant power supplies.
D . It requires that graceful Routing Engine switchover be enabled.
Answer: BD
Explanation:
B: Recent development work by many router vendors has focused on an effort to provide hitless control plane switchovers, which means keeping the control plane states in sync between the active and standby control planes prior to a switchover. Many consider this capability to be a prerequisite to delivering ISSU. Hitless control plane switch overs are usually implemented using the same version of code on both active and standby control plane components.
However, ISSU design additionally requires different software versions running on active and standby control plane components.
D: Unified ISSU is supported only on dual Routing Engine platforms. In addition, the graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) must be enabled. https://www.juniper.net/ documentation/en_US/junos15.1/topics/reference/requirements/issu- system-requirements.html Reference: https://www.juniper.net/kr/kr/local/pdf/whitepapers/2000280-en.pdf