Problem connecting 2 switches on 1 network that has 2 routers

[hennerpj]

Hi,

I have 3 Windows XP PC's connected by Ethernet cables to a Netgear FS308 5-port switch, and a Virgin Media 30Mb Super Hub is also connected by Ethernet cable to this switch.

I have 4 other PC's and a Thomson TG585 router (telphone line connection) all connected to a different Netgear switch.


I want to connect the 2 Netgear switches and I understand that this is possible with a crossover cable. I need all 7 PC's to see each other on the HOME group network so they can share files.

My problem is that it is very important that when I connect the 2 Netgear switches with the crossover cable that the 3 PC's using the Super Hub for Internet access continue to use the Super Hub only and do not try to connect to the Thomson router for Internet access. The same goes for the other 4 PC's on the other switch (I don't want them to try and connect to the Super Hub, they must contine to use the Thomson router only).

Can anybody please tell me what settings I need to change on the 7 PC's and on the Hub and router to make sure this happens?


Thank you.

Kind regards,
Paul

 

[eibgrad]

The problem is you can't easily have two networks (e.g., 192.168.1.x and 10.0.0.x) sharing the same physical network due the presence of two DHCP servers. You can't control which DHCP server will respond first to client queries. And therefore which network and gateway gets assigned to those clients becomes unpredictable.

I suppose one solution would be to use static IP configurations on ALL clients (i.e., no DHCP), but that’s nightmare to maintain.

Frankly, the proper way to use multiple ISPs is to use a dual WAN router. Now the presence of multiple ISPs is TRANSPARENT to the clients. All share the same network. A good dual WAN router can provide failover protection, load balancing, and even control which clients use which gateway based on IP, mac address, etc.

Short of a dual WAN router, your other option is to place a router between the two networks so that you maintain separation. Since DHCP traffic will not cross the WAN boundary, thus keeping DHCP server responses within their own respective LANs. Note, this will also prevent other traffic you might *want* to travel between the LANs segregated as well, such as network discovery protocols (e.g., SSDP, Bonjour). So it's not a panacea. Just depends on what you expect from the configuration.

 

[hennerpj]

Hi Eibgrad,

Apologies for the delay replying. Thank you very much for taking the trouble to provide me with this useful information.

Much appreciated.

Regards,
Paul