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Cisco 806 newbie

Unanswered Question
Dec 26th, 2002
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In 1988 I set up a private LAN in my home office consisting of

two Sunmicrosystems workstations. Following the example in the Sun

documentation I used the network IP address Since then,

the network has grown to 6 devices, but connection to the outside world

(the internet) has been only through a single computer using a dial-up

modem and PPP. This setup has worked fine.

Recently cable broadband service has become available in my area and

will soon be installed in my home office. I have purchased a Cisco 806

router to interface my private LAN to the cable modem. My

understanding is that the ethernet 0 port of the router should be

assigned a unique address on my LAN, say, and

that the ethernet 1 port connected to the cable modem should be set up

for dynamic addressing provided by my cable company IP provider.

Routing concepts are new to me but my impression was that the router

would keep my private LAN addresses from being seen by the outside

world (the internet) yet I have read that on my private LAN I should

only use IP addresses from one of the private address blocks, say the through block, else the router may get


Is this really true? Must I change the IP addresses of the devices on

my private LAN to something like 192.168.200.xxx?

Thanks for your help.

Router newbie.

Curtis Chase

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michael-faust Thu, 12/26/2002 - 13:21
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If you continue to use the network on your local LAN, you will not be able to get to that network (whoever it is???) on the internet. The router will believe (correctly) that the network is directly connected to itself, and will not forward packets to the internet for that range. The router isn't really confused; it is doing what you told it to to - but you told it to do a bad thing. Change your internal addressing to a private range to solve the problem.


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