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ipconfig .. after connecting to ISP

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Maaz
Valued Contributor

ipconfig .. after connecting to ISP

i dial my ISP, and then "ipconfig"
PPP adapter multi:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
Physical Address. . . . . . . . . : 00-53-45-00-00-00
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 202.141.240.166
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 202.141.240.166

I wana know, how my own IP could be the IP of the Gateway ? I think the Default Gateway IP must be different.. here must be a IP of a Router.
Second, plz also explain about the SubnetMask.. it is 255.255.255.255 instead of 255.255.255.0. I know subnetting but... so I think that is this a VLSM case ?

Plz help
Regards
6 REPLIES
Ivan Ferreira
Honored Contributor

Re: ipconfig .. after connecting to ISP

Indeed an extrange configuration.

The subnet mask 255.255.255.255 is normally used in routing tables to specify "just that host". That mask, in theory, should only allow the communication between you and "you". The minimum subnet mask for a two host communication should be 255.255.255.252.

Can you run for example:

pathping www.google.com
tracert -d www.google.com

Also, DHCP is not enabled, so was manually set.

As far I know, for VLSM you need a routing protocol and also, the subnet mask should have 30 bit for network as maximum.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Jorge Pinto Leite
Respected Contributor

Re: ipconfig .. after connecting to ISP

Hi

If your PPP conection is on USB, the default gateway will be 255.255.255.255, as the traffic is redirect directly to the USB adapter.
Maaz
Valued Contributor

Re: ipconfig .. after connecting to ISP

Thanks Dear Ivan Ferriera for help.
The output of "tracert -d" and pathping is attached.
>Also, DHCP is not enabled, so was manually set.

Well its again a strange thing, from the output of "ipconfig" it seems that I manually assigned the address but this is not the case... IP is assigned by my ISP. I double check the properties of my dialup connection, and its dhcp-enabled, i.e take prperties of the dialup connection > Networking(tab) > Properties of TCP/IP
(.)Obtain an IP Address automatically

Dear Jorge Pinto Leite
>If your PPP conection is on USB, the default gateway will be 255.255.255.255, as the traffic is redirect directly to the USB adapter.

No its a 3COM PCI dialup Modem(Winmodem).

May I repeat my Question... i.e
1)why the IP of Default Gateway is the same as of my own IP.
2)whats the reason that my subnet mask is 255.255.255.255. Does it means that I cant communicate with any machine.. even a machine with a IP of 202.141.240.164 and 202.141.240.167 (my own IP is 202.141.240.166). It also shows(and shows only, but not really)that Even I cant access the router at my ISP end, to access itrc.hp.com ? But I am accessing the Internet.

Plz consider me a Novice.. and Ignore my ignorance.
Looking forward for a nice help.

Thanks n Regards
Maaz
Maaz
Valued Contributor

Re: ipconfig .. after connecting to ISP

Sory I forget to attached the output in previous post. here is the output of "tracert -d" and pathping.
Igor Karasik
Honored Contributor
Solution

Re: ipconfig .. after connecting to ISP

Maaz,

>>1)why the IP of Default Gateway is the same as of my own IP.

http://www.chicagotech.net/vpntcpipsettings.htm
"Why my XP VPN client's IP is the same as default gateway IP

This is by design. Since this connection is point to point, VPN server assigns the same IP to VPN client and client's gateway."


>>2)whats the reason that my subnet mask is 255.255.255.255.

http://www.chicagotech.net/vpntcpipsettings.htm
"Why my XP VPN client's subnet mask is 255.255.255.255

This is by design. Since this connection is point to point, not point to net or net to net, VPN server assigns 255.255.255.255 mask to the client."

Athough you see word "VPN" in these answers it's same for all point-to-point connections.
When you connect to your ISP server the default gateway of your XP machine is
set to be same as received IP address. This address is the address of the PPP link to the ISP server.
So you have default route to the ISP server and all traffic will go over the PPP link to ISP server.

>>>Does it means that I cant communicate with any machine.. even a machine with a IP of 202.141.240.164 and 202.141.240.167 (my own IP is 202.141.240.166).

You can communicate with any machine through
your ISP (of course ISP can define some limitations for such connections...)
Maaz
Valued Contributor

Re: ipconfig .. after connecting to ISP

Thanks Dear Igor Karasik... nice help ;)

Regards
Maaz