Originally reported by lemmi@nerd2nerd.org as Markdown, see also https://pad.passt.top/p/MultipleAddresses > Support multiple address per address family This is probably most useful for IPv6, but there might be use-cases for IPv4 as well. > IPv6 use-case It is very common to see at least 3 IPv6 addresses on an interface. 1. link-local fe80::/64 2. unique local address (ULA) (RFC4193) fc00::/7 3. global unicast address (GUA) 2000::/3 Some local infrastructure might only be accessible via one type of address. A local resolver might only listen to requests from an ULA while still needing access to the global internet via the GUA. > Maximum number of addresses allowed Linux has a limit on how many addresses are allowed on an interface. It can be queried and set through sysctl: sysctl net.ipv6.conf.all.max_addresses Common default values vary from 16 to 32 for the number of allowed addresses. > Restrictions - Containers (pasta) Since containers can be configured directly, it should be possible to allow multiple IPv6 and IPv4 addresses. - VMs (passt) VMs on the other hand have more restrictions as the addresses need to be indirectly configured through SLAAC, DHCPv6 or DHCP. - SLAAC - can provide multiple prefixes of varying length - might not be feasible to force multiple specific addresses within a single prefix - DHCPv6 - has support to configure multiple addresses - client support might be lacking - DHCP - impossible