Re: Wondering about doing something strange with networking
On Tue, Oct 27, 2009 at 07:58:18AM +0000, Alan Chandler wrote:
> The remainder of the devices - although ideally should use dhcp, could
> be configured with static addresses (and therefore also routes) to
> regard eth0:0 on the plug computer as a gateway (the plug computer would
> use 192.168.0.1 as its eth0:0 interface IP address, the dhcp allocated
> address on eth0 would not be in that range).
>
> I think, in this scenario, the switch would soon learn not to send arp
> messages saying who has 192.168.0.x address to the cable modem,
> (although I am not sure it would matter if it did).
>
> What I am less certain about is how I can cater for Wireless clients
> coming in over the WAP, who do really need dhcp allocated addresses. My
> guess is that they would be requesting leases via some broadcasting
> mechanism, and that there is no way for the ethernet switch to prevent
> them going to the cable modem (and thence to my isp) and the dhcp server
> at my isp responding.
>
> Is what I am trying to consider impossible?
No, it can work. You are just confused.
The switch does not know anything about IP addresses. It
understands ethernet MAC addresses.
$ /sbin/ifconfig
eth0 Link encap:Ethernet HWaddr 00:24:1d:28:73:b6
inet addr:10.1.4.55 Bcast:10.1.255.255 Mask:255.255.0.0
inet6 addr: fe80::224:1dff:fe28:73b6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:12194355 errors:0 dropped:173155950949126
See that HWaddr: field?
That's a MAC address. It should be unique on every network
interface.
Routers are devices that make decisions on the IP level.
Switches make decisions on the ethernet level.
What you will have problems with is running DHCP, as you
mentioned. Here's what you do:
Get a USB-ethernet connector for your plug. Now you have two
ethernet ports. One goes to the cable modem, one goes to your
switch. Life is good.
Alternatively, hardcode IPs for everything on that switch. You
can either hardcode IPs for your wireless devices, or run DHCP
on a separate subnet there.
-dsr-
--
http://tao.merseine.nu/~dsr/eula.html is hereby incorporated by reference.
You can't defend freedom by getting rid of it.
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