Switch vs router?

maxsanders · 07-16-2007, 07:13 AM

Network switches typically have one "uplink" port and several other ports.

The difference is apparently one of "crossover".

My http server/firewall/router signal is distributed to the "uplink" port...then to two tiers of network switch through the uplink ports.

My problem is that I need to attach my Linux Terminal server/ DHCP server at the opposite end of the stream from my firewall/dhcp server/router.

This seems not to work. Do I need routers in place of the network switches to allow routing is both directions?

Here is the diagram:

Code:

                         WAN   internet
                          ||
                         HTTP server/router/firewall
                         ||
                   network switch
              ||            ||           ||
            client         client       client
                             ||
                           network switch
                             ||                         ||
                      DHCP server/terminal server      client

Can this be made to work? I know I could move up the DHCP/terminal server, but I am trying to understand possible network configurations and how these switches work. Thanks

Simon Bridge · 07-16-2007, 07:29 AM

The client with two switches is a gateway between networks and so will have to do NAT and some routing. Is that the idea?

maxsanders · 07-16-2007, 08:54 AM

The box with HTTP server/ router/firewall does NAT/masquerading to get data from the modem IP passthrough (192.168.1.100) eth0
to the The second NIC on this box for the private network (192.168.2.100) eth1

Everything works....internet and file sharing works on everything except the data distribution from the DHCP server on the end of the line.

I know the network architecture is strange...it just evolved this way as I learned this stuff one project at a time (Apache/NAT/firewall/DHCP server/Terminal server.)

My switches are inexpensive Linksys/ Dlink consumer level items. They are not programmable so far as I know. Do I need a router at these points instead of switches if I want to distribute the DHCP data from the box at the end of the private network?

Thanks.

Crito · 07-16-2007, 10:26 AM

The terminology you're using confuses the !@#$ out of me. I'm still trying to figure out what "at the opposite end of the stream" and "modem IP passthrough" means.

Anyway, an uplink port, as you discovered, just crosses the TX/RX pairs. You can use a regular crossover cable plugged into a regular port and it'll do the exact same thing. So just plug the switches into the router and the clients into the switches.

Code:

          router
            |
 client-- switch --client
            |
 client-- switch -- DHCP server

Ethernet with CAT5 uses a star topology, so there are no "ends" to terminate as with coaxial cable.

maxsanders · 07-16-2007, 11:00 AM

For some reason I was not thinking clearly about the star topology and had a linear model in mind. Things work great now, and thanks again.