Currently I have a network with 1 ISP, a router/modem, Gigabyte Switch and a server.

All the clients PC are automatically assign IP from DHCP server from a Router/Modem A.

Server A have a fixed IP (eg:, installed Linux - used for a Web Server, Asterisk, and Backup use.

I need a new second ISP with separate modem but I want Server B (eg: use ISP B network only. For example if I download anything or use SIP (Asterisk) from Server B - It will use ISP B connection and not other ISP connections. Also any clients PC should be able access to Server A ( or Server B (

How can it be done? See example design below I think it might work?

Server B have two Ethernet Ports (One for Modem/Router and other connected a switch)

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  • If you want to go the appliance route, try something like this. – ewwhite Jan 30 '13 at 13:03
  • @ewwhite Nah I don't want that. – I'll-Be-Back Jan 30 '13 at 13:09
  • Then static routes. – ewwhite Jan 30 '13 at 13:10
  • @ewwhite Please post answer if you can - how can it be done and is my network design is correct. – I'll-Be-Back Jan 30 '13 at 13:13
  • Looks correct... Make sure the default gateway on Server B points to the ISP. – ewwhite Jan 30 '13 at 13:14

Setup Server B as usual (pppoe/dhcp to ISP B via Router/Modem B) and configure the second NIC (that is facing the Switch) with a static IP address, OR you can configure that 2nd nic with DHCP as well but take care not to configure the Router/Modem A as gateway.

With dhcpcd(8) you can to this with --nogateway or with dhclient(8), remove the routers from the parameters of the request clause in dhclient.conf.

  • Thanks for answer. Can clients can access to Server A (web server) and Server B (web server) even all the clients PC IP are assigned from Router/Modem A gateway. All the clients PC are Windows OS – I'll-Be-Back Jan 30 '13 at 15:01
  • Sure, they are within the same Layer2 subnet, no router blocks their communication. – Endre Szabo Jan 30 '13 at 15:10

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