IPv6 Behavior During Unified ISSU

Unified in-service software upgrade (ISSU) supports IPv6 instances. You can perform unified ISSU on E Series routers without disconnecting IPv6 subscriber connections (DHCPv6/PPPv6) and without disturbing the IPv6 unified ISSU-supported routing protocol configuration. IPv6 traffic forwarding through the chassis experiences minimal disruption. IPv6 configuration is retained after the upgrade and all IPv6 and dual-stack subscriber sessions established prior to performing unified ISSU remain established.

IPv6 applications can send and receive control plane traffic during the unified ISSU operation except during the switch route processor (SRP) module upgrade and forwarding controller upgrade phases. IPv6 data plane traffic forwarding will continue after the unified ISSU operation with minimal traffic forwarding outages during unified ISSU. The static neighbor entries and the dynamically learned neighbor entries which are in the reachable state in the line module are not disturbed during unified ISSU. This causes traffic outage disruption in IPv6 traffic forwarding through the chassis to be 30 seconds or less than 30 seconds.

Note: Unified ISSU is not supported for IPv6 configurations and IPv6-related applications that are not supported for the IPv6 high availability feature.

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