[LU-14288] Enhance nodemap ranges to work better with IPv6

Related — Sat, 20 Jan 2024 14:35:07 +0000

The nodemap functionality in lustre allows sets of hosts to be described using a range of network addresses.

For network types where the address is a simple integer, this seems reasonable.

For IPv4 where an address is usually represented as 4 small integers, this is manageable, but not really ideal. The standard throughout IP is to use a netmask to identify a set of addresses, whether for routing, for access control, or any other purpose.

For IPv6 it would be quite inconvenient to use ranges. Addresses are rarely allocated sequentially, and specifying a netmask length is much easier. Also, it is standard practice to store IPv6 address (and IPv4) in network-byte-order, so comparing two addresses to see if they are ordered (as needed for ranges) is clumsy to implement.

Clearly we need to keep address-range support for existing address types, but I believe we should not support it for new IP address. Further we should add netmask support for existing address types.

Internally, this would mean keeping nodemap information in a range-tree for 4-bytes addresses (as we already do), and using a netmask based structure for longer addresses.

From user-space, we would add a syntax (/nn suffix) to specify a netmask. For 4-byte addresses this would be converted to a range. For large address, this would be used as-is.

Whamcloud Community JIRA

[LU-14288] Enhance nodemap ranges to work better with IPv6