Which two features are used to allow a nondisruptive upgrade for the ISSU process? (Choose two.)

A connectivity management processor (CMP) provides out-of-band management access but does not directly contribute to the nondisruptive nature of ISSU.

Nonstop Forwarding (NSF) allows a router to continue forwarding packets even after a routing process failure or during a switchover to a standby supervisor, ensuring data plane continuity during an ISSU.

Graceful Restart (GR) is a mechanism that allows a routing protocol neighbor to continue forwarding traffic based on known routes even if the peer routing process restarts, but it relies on NSF and SSO for its functionality during an ISSU.

Stateful Switchover (SSO) provides redundancy by maintaining control plane information (like routing tables, adjacency tables, and session state) on a standby supervisor, enabling a rapid and seamless switchover in the event of an active supervisor failure or during an ISSU.

An advanced services license might enable certain features, but it is not a direct technical feature that facilitates a nondisruptive ISSU process.