Today at work, we received an ATEN/ALTUSEN KN2132 KVM switch. Unlike our previous KVM switch, this model has IPv6 capability.

Sadly, version 1.8.174 of the firmware contains an annoying bug. If you want to use SLAAC, then the firmware neglects to invert the universal/local bit while transforming the MAC-48 address to a modified EUI-64 format interface identifier.

E.g., if the MAC address is 00:10:74:92:09:BA, then the corresponding modified EUI-64 format interface identifier must be 0210:74FF:FE92:09BA. Version 1.8.174 transforms the MAC address into 0010:74FF:FE92:09BA. How rude.

The firmware does manage to combine the prefix announced by the router with the improper interface identifier, e.g. 2001:DB8::10:74FF:FE92:9BA.

It also appears that the firmware doesn’t respond to ICMPv6 echo requests targeting the corresponding link-local address, i.e. FE80::10:74FF:FE92:9BA, nor FE80::210:74FF:FE92:9BA.

Most people would simply configure a manual IPv6 address and be done with it, but I guess ATEN should put some effort into adhering to the norm. In particular, the engineers at ATEN should read sections 2.5.1 and 2.5.6 of RFC 4291, and the entire RFC 4862.