This is a a question about a private network.

I have two servers (Linux), srv1, srv2, each has one NIC. I have two switches (Cisco 3750), sw1, sw2

The servers are on two different subnets.

srv1 is on (network A, sw1) .> the A and B are not classes, only represent the networks for the question

srv2 is on (network B, sw2)

If A wants sends out traffic for B via sw1 (the one A is physically connected to) and ip routing is turned on on the switches, sw1 & sw2, do I need a specific gateway for the sw2 traffic?

Let me ask another way,

  • If svr1 send traffic to svr2 and I only have one physical network connection to to sw1, what happens to the packet?
  • Will packet ever make it to the Cisco switch from the box?
  • Or does it get to the switch and die?
  • Get routed?
  • Isn't a unique gateway only need when you have more than one physical NIC?

I simplified the question, but in reality the sw2 subnet is on a private network along with many devices, specifically a SAN I want sw1 to be able to get to (and vice-versa).

1 Answer 1


You have to have routing set up correctly.

For example: SRV1 IP: SRV2 IP:

SW-A IP: SW-B IP: (these you can set up as interface VLAN and switches should be interconnected)

In order for SRV1 to access SRV2, you should set the routing on SRV1 to: via

And on SRV2 (for reverse packet) via

Hope it helps

  • So on the first server (.1), if I try to ping .2, I can't see it, but if I put a route in .1 to use switch1 for the .2 traffic, it will work, assuming if have IP Routing turned on in the switches?
    – johnny
    May 9, 2016 at 15:05
  • yes, and switches should be connected to each other to pass this traffic May 9, 2016 at 15:09

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