Group Manager uses IPv6 link local networking to communicate between iDRAC’s (excluding the web browser GUI). Link local communication is defined as non-routed packets which means any iDRAC separated by a router cannot be joined in a local group. If the iDRAC-dedicated port or shared LOM is assigned to a vLAN, the vLAN limits the number of iDRAC’s that can be joined in a group (iDRAC’s must be on the same vLAN and traffic must not pass through a router).
When Group Manager is enabled, iDRAC enables an IPv6 Link Local address regardless of the iDRAC's current user-defined network configuration. Group Manager can be used when iDRAC is configured for IPv4 or IPv6 IP addresses.
Group Manager uses mDNS to discover other iDRAC’s on the network and sends encrypted packets for normal inventorying, monitoring, and management of the group using the link local IP address. Using IPv6 link local networking means that the Group Manager ports and packets never leave the local network or be accessible to external networks.
Ports (Specific to Group Manager unique functionality does not include all iDRAC ports) are:
5353 (mDNS)
443 (webserver) - configurable
5670 (Multicast group communication)
C000 -> F000 dynamically identifies one free port for each member to communicate in the group
NOTE:Security scanners flag Group Manager usage of mDNS on the IPv6 link local network to discover neighbor iDRAC’s. iDRAC sends group name, Service Tag, and IPv6 address in the mDNS record.