edhalen
orange whip?
Premium
join:2002-05-16
Yorkville, IL
clubs:
1 edit | Speedstream 5100b and Netgear RP614 question
I know there's a Netgear forum but I would like to ask the experts here first. 
Anyway, I notice on my speedstream that generally the IP is say .159 and the Gateway shows .254 - pretty standard. I have PPPOE on the modem and I'm transferring the public IP to the router - so I can get to the modem stats. My Netgear shows the same public IP as the Modem but shows the gateway as .158 rather than 254. Anybody know the reason for that? Things seem to work fine I am just wondering why.
Thanks
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edhalen
orange whip?
Premium
join:2002-05-16
Yorkville, IL
clubs: | anyone?
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nwrickert
sand groper
Premium,MVM
join:2004-09-04
Geneva, IL
 ·AT&T U-Verse
 ·AT&T Midwest
| reply to edhalen
I don't have a 5100b to experiment with. But I had been wondering how they did it.
When the 5100b gives the public IP to the computer (or router in your case), it still needs to make sure that any outbound packets go through the modem. It can't give "192.168.0.1" as the gateway address, since that is not even on the same subnet.
Presumably it (the 5100b) gives a phony gateway and netmask, that will be such that the computer or router sends outbound packets through its WAN interface. Once they are on the WAN interface, the 5100b can intercept them and send to the real gateway.
Does your router tell you what is its WAN netmask? |
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edhalen
orange whip?
Premium
join:2002-05-16
Yorkville, IL
clubs: | reply to edhalen
Internet port (WAN) netmask is 24 bit (255.255.255.0)
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nwrickert
sand groper
Premium,MVM
join:2004-09-04
Geneva, IL
·AT&T U-Verse
·AT&T Midwest
| Interesting. That's what I guessed it would be.
The way IP works over internet, if the netmask is as you list, then the gateway has to be on the same xxx.yyy.zzz.* as your xxx.yyy.zzz.159. However the usual *.254 gateway often has a different prefix. PPP allows a gateway not closely related to the actual IP, but IP over ethernet doesn't. So the modem fudges it, by pretending that 158 is the gateway. |
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edhalen
orange whip?
Premium
join:2002-05-16
Yorkville, IL
clubs: | reply to edhalen
Thanks for the explanation . I knew somebody would have the answer. 
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