This IP confused me...

[rgao]

Hi,there

I use dial up internet connection, after I connected internet I use ipcongig /all to check my ip address, there is something confused me, i hope some one can help me.

first question :my ip dhcp enabled is set to no.Did the ISP dynamicaly assign ip to client or not?

second question:my ip gateway is myself and my ip routing is not enabled. how can i send out my request,if it goes to gateway it will come back to my pc.it can not be sent out.

I think it's because dial up internet use PPP,but how to send datagram in PPP, not through gateway? no need for ip routing? could any one give me some clue or answer?

thanks in advance
rgao

 

[Grenage]

This is all normal. The gatway is the IP address of the device with a connection to the internet, if you had other machines on your network they would use your IP as a gateway to access the internet. Obviously the ISP would have to assign you a public IP address, your computer is simply telling you that there is no DHCP server on your network.

 

[rgao]

Hi,Grenage
Thanks for your reply.but I'm still confused...
normally when system received a packet, it check the destination,if it match itself the system will receive it,otherwise system will discard it,if ip routing is not enabled.so when my pc got packet (because it's gateway) he check the destination ,found it dosen't match,and ip routing isn't enabled, my system has no idea where to send it, this packet will be discard.
Any thought about it?

Thanks again

 

[Grenage]

IP routing is only used on machines to connect 2 LANS together is it not ?

It wouldn't be required for you machine to access or be accessed from the internet.

 

[fiaery]

I'm no expert. Let me attempt to answer:

Your ISP would definitely have to assign you a public ip address (as opposed to having their clients choose their own ip addresses- imagine the confusion and conflicts that would arise!)

Like what Grenage said, routing is required when 2 or more computers are networked, as the data packets have to be 'directed' to the proper ip address. In this case only your computer is connected to the ISP. In this aspect, Peer-to-Peer Protocol is used as the ISP's server is regarded as a 'peer' that connects you to the internet. A TCP/IP datagram (packet) rides on the PPP protocol to your ISP's server. Following this line of thought, How did do you know that your gateway is yourself? Look at your DHCP settings, or your dialup adapter settings. thought your ISP should provide you with a gateway setting.

In any case just because its a gateway does not imply it cannot send and receive to/from itself. once the request has been sent out and reaches a router (probably the ISP), the router will direct the request to the proper address (in this case, back to the computer). This is why you can ping yourself. works the same way.

I suggest the site

http://computer.howstuffworks.com/router3.htm