I have set up a network in a non-standard way, and would like to know if what I did is technically correct, or if I just got lucky.
The setup works fine with my $20 5-port Linksys switch, but not with my $1200 Allied Telesys Fiber SFP/GigE switch :|
We have dedicated Internet access through AT&T via Ethernet, and have been assigned an IP block like:
32 bit IP address minus 27 bit mask = 5 bits, so we have 5 bits worth of IPs in our subnet, 2^5 = 32 addresses, making our subnet mask is
This means that our 'network' is
220.127.116.11, and we have 30 IP addresses, from
18.104.22.168 being the 'broadcast' address for our network.
We were told that the AT&T gateway is
22.214.171.124, and our gateway should be
Normally to provide access to the Internet you would have a router with the IP address
126.96.36.199 on the ISP side, and
188.8.131.52 on our side, then use
184.108.40.206 - .254 for local devices or other routers.
The router is what allows communication between devices on the 12.12.12.x subnet and the 220.127.116.11 gateway, which is clearly a different subnet. (This is the extent of my networking knowledge; past this, I don't have a clear understanding.)
However, since we're using multiple NAT routers on our side of the connection, each serving a different location with Internet access, I am bypassing the "main" router entirely.
We plug the AT&T Ethernet connection directly into a switch, then the WAN interface of the router for each location plugs into the same switch. Each router uses the AT&T gateway of
18.104.22.168 and a subnet mask of
255.255.255.224 with an IP from our range of
22.214.171.124 - .254 for its WAN interface.
My understanding is that this should still work fine even though the IP of our router is
126.96.36.199 and the IP of AT&T's gateway is
188.8.131.52, and they are on separate subnets, because they are on the same switch, and an ARP request would find that they can communicate with each other directly, without a router...
...and it does work, when the AT&T Ethernet and the Ethernet from each of our routers are all plugged into my cheapo Linksys 5-port desktop switch. But when I try to plug them in through my expensive Allied Telesyn (layer-2) switch, it works "fine" for 4 hours, then our routers lose communication with the Internet and have to be reset. The routers don't freeze or hard-lock, you can still log in to them locally, you just can't reach them from the Internet, or reach the Internet from behind them - not even pings.
Does anyone have an academic answer for why this may be?
Is what I've done completely ridiculous? Or is there just some setting I'm missing. The expensive switch is just a layer-2 switch, so I'm not sure what "settings" there could be on it. Maybe it's too smart, and doesn't like my hack-y configuration.
Should this type of set-up theoretically work?
Interested in your thoughts!
*some IPs have been changed to protect the innocent