Subscriber subnet SRRP gateway IP address connectivity

The SRRP gateway IP addresses on the subscriber subnets cannot be advertised as /32 host routes because they may be active (master) on multiple group IP interfaces on multiple SRRP routers. Without a /32 host route path, the network forwards any packet destined for an SRRP gateway IP address to the closest router advertising the subscriber subnet. While a case may be made that only a node that is currently forwarding for the gateway IP address in a master state should respond to ping or other diagnostic messages, the distribution of the subnet and the case of multiple masters make any resulting response or non-response inconclusive at best. To provide some ability to ping the SRRP gateway address from the network side reliably, any node receiving the ICMP ping request responds if the gateway IP address is defined on its subscriber subnet.