Why Dial up connection uses extra IP address

  • Thread starter Thread starter Jon
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J

Jon

After creating an incoming VPN connection on a XP Pro PC
I notice that when I check my adapters and IP's
using 'ipconfig /all', I see an additional IP assigned to
the PPP adapter RAS Server (Dial In) Interface. Is this
refered to as a 'virtual adapter'? The other IP address
accociated with this PC is listed under the NIC adapter.
This IP is statically configured on the XP Pro. What is
really puzzeling me is on the menu (IP addresses served)
of the router that issues the addresses DHCP, I see that
the same PC has four IP addresses that have been assigned
to it not including the static IP on the machine. When I
make the VPN connection I notice under the 'details' tab
in the 'properties' of the connection that two of the
IP's are listed, one as server and the other as client.
All in all there are five IP's aasociated to one PC that
has one NIC adapter and a Linksys switch between it and
the router issuing IP's by DHCP. The DHCP pool contains a
limited number of IP addresses that are public type
addresses. Whatever is taking place is using up more
addresses then I would like. Is there any way to reduce
the number? Thanks.
 
Jon said:
After creating an incoming VPN connection on a XP Pro PC
I notice that when I check my adapters and IP's
using 'ipconfig /all', I see an additional IP assigned to
the PPP adapter RAS Server (Dial In) Interface. Is this
refered to as a 'virtual adapter'? The other IP address
accociated with this PC is listed under the NIC adapter.
This IP is statically configured on the XP Pro. What is
really puzzeling me is on the menu (IP addresses served)
of the router that issues the addresses DHCP, I see that
the same PC has four IP addresses that have been assigned
to it not including the static IP on the machine. When I
make the VPN connection I notice under the 'details' tab
in the 'properties' of the connection that two of the
IP's are listed, one as server and the other as client.
All in all there are five IP's aasociated to one PC that
has one NIC adapter and a Linksys switch between it and
the router issuing IP's by DHCP. The DHCP pool contains a
limited number of IP addresses that are public type
addresses. Whatever is taking place is using up more
addresses then I would like. Is there any way to reduce
the number? Thanks.
Click to expand...

Jon,

each outside connector of a device needs exactly one IP address.

Occasionally it is possible to have more than one IP address
active at the same time on one outside connector. A good example
is that you run a PPPoE connection over an Ethernet adapter that
at the same time serves a LAN over a normal Ethernet IP
connection. Essentially you have two virtual connectors here
that share the same physical connector.

If the router assigns IP addresses to your computer's connector,
even though it already has a static one, then either the router
or the computer is defective. The computer will normally not ask
DHCP for an IP address if it already has one, so I suspect the
router.

Hans-Georg
 
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