I'm using Ubuntu 14.04 (standard server install + OpenSSH, biosdevname=0 during instal to keep the network names simple) in an environment where I have two non-overlapping subnets M and N on different VLANs.

For the purpose of debugging an issue on one of the subnets, I want to configure my server such that it can receive traffic on eth0 from an IP on subnet M, and on eth1 from an IP on subnet N.

I realize I can only have one gateway, so I use the gateway from subnet M. I set up /etc/network/interfaces such that subnet M is fully specified with an IP A.B.C.42 (which works normally) and from subnet N I've chosen an IP address X.Y.Z.88 and provided the appropriate netmask for that subnet (it doesn't overlap with subnet M at all).

I can bring up eth1 via `sudo ip addr flush dev eth1; sudo ifdown eth1; sudo ifup eth1`... this appears to work and my routing table is:

```
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         A.B.C.1         0.0.0.0         UG    0      0        0 eth0
A.B.C.0         0.0.0.0         255.255.255.192 U     0      0        0 eth0
X.Y.Z.64        0.0.0.0         255.255.255.224 U     0      0        0 eth1

```

Note that the adapters are valid and working per `sudo lshw -c network` etc. 

**At this point, *assuming there is no blockage on subnet N*, should I be able to ping or ssh to this server via subnet N (using IP X.Y.Z.88)?** (Subnet M with IP A.B.C.42 definitely works.) If not, what obvious steps / tests am I missing?

(I've seen similar questions around here and elsewhere but so far haven't found one that has this configuration (totally separate subnets for example). I'm really trying t determine if subnet N is blocking traffic or is otherwise acting up.)