Why does my DSL modem list more than one physical address?

Question

OS : Windows XP 32 Modem: Huawei MT882

What little I know, physical address is typically unique for a given network adapter. Why then does ipconfig /all give me more than one physical address listed?

Ethernet adapter Local Area Connection:

    Connection-specific DNS Suffix  . :
    Description . . . . . . . . . . . : Huawei MT882 USB Remote Network Device
    Physical Address. . . . . . . . . : 00-0F-A3-56-9F-0B
    Dhcp Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    Autoconfiguration IP Address. . . : 169.254.52.223
    Subnet Mask . . . . . . . . . . . : 255.255.0.0
    Default Gateway . . . . . . . . . :

PPP adapter BB-1:

    Connection-specific DNS Suffix  . :
    Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
    Physical Address. . . . . . . . . : 00-53-45-00-00-00
    Dhcp Enabled. . . . . . . . . . . : No
    IP Address. . . . . . . . . . . . : 59.95.64.201
    Subnet Mask . . . . . . . . . . . : 255.255.255.255
    Default Gateway . . . . . . . . . : 59.95.64.201
    DNS Servers . . . . . . . . . . . : 218.248.240.208
                                        218.248.240.135
    NetBIOS over Tcpip. . . . . . . . : Disabled

Answer 1

You have the Ethernet adapter, and you have the PPPoE virtual adapter. Two adapters, two connections, two addresses.

Answer 2

Notice that for the USB adapter it lists an "Autoconfiguration IP address" in the 169.254.* space. These addresses are generated completely at random by Windows when connecting to a network with no DHCP service. They are non-routable and intended for use on very small private networks, such as Ad-Hoc wifi networks and, in this example, a point-to-point IP link between two devices.

The first interface you see is the connection between your computer and the USB adapter itself - it's a direct link from device-to-device that's used to interface with the product. It is not attached to the Internet, and that IP will never be seen outside of your USB cable.

The second interface is the actual Internet interface on the USB adapter, which it exposes to Windows through the first interface using Point-to-Point Protocol (PPP). So, if you'd like, you can think of the first interface as being a very small LAN made up of your computer and the adapter, and the second interface as your actual Internet connection which is tunneled through the LAN.