Asking about IPv6 address

[berlowin]

Hello all,

when i type ifconfig, and the output is:
$ ifconfig
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=1b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING>
inet6 fe80::213:20ff:feac:ddca%em0 prefixlen 64 scopeid 0x1
inet 122.200.6.110 netmask 0xffffff00 broadcast 122.200.6.255
ether 00:13:20:ac:dd:ca
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active

I want ask why the bold and the underline output is always started with FE80? even though i change my NIC, it always start with FE80.

Last question, is 213:20ff:feac:ddca%em0 the MAC address of the NIC? Because when I change my NIC, it always change the address too.

does anybody have the reference?

Thank you very much.

waiting for your replied soon.

Regards,
berlowin

[BSDfan666]

That happens to be the link-local address, OpenBSD(and I assume the others..) assign a link local address for each interface.

http://tools.ietf.org/html/rfc3484

[BSDfan666]

Originally Posted by berlowin

I want ask why the bold and the underline output is always started with FE80? even though i change my NIC, it always start with FE80.

Because that subnet was reserved for link-local IPv6 addresses. (fe80::/10)

IPv4 has a similarly reserved range, 169.254.0.0/16.

Originally Posted by berlowin

Last question, is 213:20ff:feac:ddca%em0 the MAC address of the NIC? Because when I change my NIC, it always change the address too.

No it's not, 00:13:20:ac:dd:ca is your MAC address... a unique link-local address is generated for each "physical" interface.

EDIT: This seems like a decent introduction, Google is your friend: http://www.enterprisenetworkingplane...le.php/3633211