MAC Address and IPv6
What a hardware address says about itself, and whether an IPv6 address holds one.
00:1a:2b:3c:4d:5e
The same address, written three ways
| Colons | 00:1a:2b:3c:4d:5e |
|---|---|
| No separator | 001a2b3c4d5e |
| Dotted (Cisco) | 001a.2b3c.4d5e |
What the first octet says
Universally administered, so the first three octets are a registered vendor prefix.
Individual, so it addresses one interface.
| Vendor prefix | 00:1a:2b |
|---|
The IPv6 address it forms
| Modified EUI-64 identifier | 02:1a:2b:ff:fe:3c:4d:5e |
|---|---|
| Link-local address | fe80::21a:2bff:fe3c:4d5e |
FF FE goes in the middle and the universal bit is inverted (RFC 4291 Appendix A). Converters skip the inversion, which is why some of them print fe80::1a:2bff:fe3c:4d5e where this prints fe80::21a:2bff:fe3c:4d5e.