IPv6 subnet mask sizes

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There are potentially billions of devices to be pinged within a single IPv6 subnet. To ensure that discovery completes, you must specify a sufficiently large netmask if you specify an IPv6 subnet as a ping seed.

The following table provides examples of IPv6 subnet mask sizes configured within ping seeds and the corresponding estimated time required to ping the devices in the subnet. The estimated times are based on spacing the pings by 100 ms between pings. This table shows that it is best to limit the size of IPv6 subnet masks in your subnet seeds.

Table 1. Ping response times for IPv6 subnet masks
IPv6 subnet mask size	Number of IPv6 addresses in subnet	Estimated ping time for subnet
120	256	26 seconds
112	65536	1 hour 48 minutes
100	268 million	Approximately 8.5 years

The time estimates shown in the table refer to time taken to ping all the seeds in a subnet seed specified for the Ping finder. It would take longer to complete the discovery as there will be many more devices to ping within the discovery scope.