AntiOnline Spotlight Tutorial: IPv6: Page 2

Important to note about the LLA is that IPv6 will assign this address —and the computer will keep it—even after the computer has been assigned a routable address (in my case, that would be a ULA). This is not the case with IPv4: if a computer is assigned a routable address, the secondary APIPA address is dropped.

Something else you may have noticed: the "%8" behind the IPv6 address. See "Zone ID’s" below for an explanation.

Below is the complete output from my "ipconfig /all" command:

C:UsersDries>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : Dries-Dell
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : tx.rr.com

Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . : tx.rr.com
   Description . . . . . . . . . . . : Intel(R) 82562V 10/100 Platform LAN Connect
   Physical Address. . . . . . . . . : 00-19-D1-08-1B-6D
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::4cea:2560:8d8c:289d%8(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.1.102(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Monday, July 28, 2008 6:19:30 PM
   Lease Expires . . . . . . . . . . : Thursday, August 07, 2008 7:24:53 AM
   Default Gateway . . . . . . . . . : 192.168.1.1
   DHCP Server . . . . . . . . . . . : 192.168.1.1
   DNS Servers . . . . . . . . . . . : 24.93.41.127
                                       24.93.41.128
   NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter Local Area Connection* 11:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
   Physical Address. . . . . . . . . : 02-00-54-55-4E-01
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 18:

   Connection-specific DNS Suffix  . : tx.rr.com
   Description . . . . . . . . . . . : isatap.tx.rr.com
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::5efe:192.168.1.102%20(Preferred)
   Default Gateway . . . . . . . . . :
   DNS Servers . . . . . . . . . . . : 24.93.41.127
                                       24.93.41.128
   NetBIOS over Tcpip. . . . . .

Note how there are three local area connections (Ethernet adapter Local Area Connection, Tunnel adapter Local Area Connection* 11, and Tunnel adapter Local Area Connection* 18). The first adapter is our regular network adapter, as covered above. The second and third adapters are interesting, as they signify transitioning technologies (implemented to make IPv4 and IPv6 coexist). The second is a "Teredo Tunneling Pseudo-Interface."

Teredo is a protocol that allows computers to use IPv6 over the Internet, even if those computers are behind routers that only support IPv4 (such as in my case). The third is an ISATAP connection, with ISATAP standing for Intra-Site Automatic Tunnel Addressing Protocol. This, like Teredo, is an intermediary protocol (to facilitate communication between IPv4 and IPv6).

The ISATAP address (fe80::5efe:192.168.1.102) is interesting, as you can clearly see in it the private IPv4 address of my computer (192.168.1.102); this is because ISATAP encapsulates the IPv4 address within an IPv6 address.

Zone ID’s

The only thing left to explain is the "%8" behind the first adapter’s LLA, and the "%20" behind the third adapter’s LLA. All LLA’s have the same network ID (fe80), so it’s impossible to tell from the network ID what interface is connected to it (in my case, it could be the Ethernet adapter Local Area Connection, or it could be the Tunnel Adapter Local Area Connection* 18 — both have an LLA). To specify what interface you are referring to, the zone ID is used (8 and 20 in my case, respectively).

To get an overview of assigned zone ID’s, issue the following command:

C:UsersDries>netsh interface ipv6 show interface

Idx  Met   MTU   State        Name
---  ---  -----  -----------  -------------------
  1   50 4294967295  connected    Loopback Pseudo-Interface 1
 12   10   1280  disconnected  Local Area Connection* 11
  8   20   1500  connected    Local Area Connection
 20   25   1280  connected    Local Area Connection* 18

As a last note: IPv6’s loopback address. Where IPv4’ is 127.0.0.1, IPv6’s is ::1 (and by now, you should know that that’s actually 0000:0000:0000:0000:0000:0000:0000:0001).

C:UsersDries>ping ::1

Pinging ::1 from ::1 with 32 bytes of data:
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms

Ping statistics for ::1:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms

Further Reading

Microsoft - IPv6 - Link

This article was first published on EnterpriseITPlanet.com.