Solved: IPv6 addressing

johnlloyd_13 · ‎11-29-2008

all,

i tried to do an ipv6 install on my windows xp machine and i got this output:

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

IP Address. . . . . . . . . . . . : 10.80.104.245

Subnet Mask . . . . . . . . . . . : 255.255.252.0

IP Address. . . . . . . . . . . . : fe80::21a:6bff:fe47:b915%5

Default Gateway . . . . . . . . . : 10.80.104.1

i have some few questions:

1. what does the percentage (%) represent in the address format. is this the /prefix? i know ipv6 address format are in hex and colon (:)

2. are host PCs able to auto configure themselves for ipv6? is this a feature?

3. is this host doing a dual stack ip address scheme?

4. does a LAN ipv6 addresses always start with fe80?

Giuseppe Larosa · ‎11-30-2008

Hello John,

1) I don't understand the % looks like a visualization error

2)

However the FE80/10 are the link local addresses that are used on every LAN interface.

They provide a basis for communication over a network segment.

Of course this prefix is not routable.

Also routers use it for building adjacencies this is the case of OSPFv3

Here the host portion 64bits is made of the EUI transformation of the NIC MAC address.

see

http://www.cisco.com/en/US/docs/ios/12_2t/ipv6/v6addres.html#wp1332105

3) yes it is dual stack

4) as told above fe80/10 is a special class of addresses used for link local on link communications. When connected to a network a NIC can get multiple ipv6 addresses including multiple private (unique local addresses) or public ipv6 addresses (Aggregatable global address)

again see

http://www.cisco.com/en/US/docs/ios/12_2t/ipv6/v6addres.html#wp1332105

Hope to help

Giuseppe

View solution in original post

Giuseppe Larosa · ‎11-30-2008

Hello John,

1) I don't understand the % looks like a visualization error

2)

However the FE80/10 are the link local addresses that are used on every LAN interface.

They provide a basis for communication over a network segment.

Of course this prefix is not routable.

Also routers use it for building adjacencies this is the case of OSPFv3

Here the host portion 64bits is made of the EUI transformation of the NIC MAC address.

see

http://www.cisco.com/en/US/docs/ios/12_2t/ipv6/v6addres.html#wp1332105

3) yes it is dual stack

4) as told above fe80/10 is a special class of addresses used for link local on link communications. When connected to a network a NIC can get multiple ipv6 addresses including multiple private (unique local addresses) or public ipv6 addresses (Aggregatable global address)

again see

http://www.cisco.com/en/US/docs/ios/12_2t/ipv6/v6addres.html#wp1332105

Hope to help

Giuseppe

johnlloyd_13 · ‎11-30-2008

thanks giuseppe! as always, your answers enlighten me! i was able to see this on microsoft technet for my first question: % is used to separate address and zone id (i believe zone id is also equivalent to prefix)

http://technet.microsoft.com/en-us/library/bb726952.aspx

Harold Ritter · ‎11-30-2008

John,

The zoneid is a logical identifier assigned to a physical or logical interface on the device. Since the same link-local address can be reused on all interfaces, the %zoneid indicates the interface to which the link-local address is assigned.

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
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