Dual Port Configuration

Firefly86 · 28 Jun 2007 at 15:31

Hi guys,

I need some help am really confused here.
Ive got a HP Dual Port Network card NC7170

Ive installed 1 card each on 2 servers

Server 1 Config

LAN 1 : 10.0.1.6
Subnet : 255.255.0.0
LAN 2 : 10.0.1.7
Subnet : 255.254.0.0

Server 2 Config

LAN 1 : 10.0.1.9
Subnet : 255.255.0.0
LAN 2 : 10.0.1.10
Subnet : 255.254.0.0

The problem I'm having is that I can't seem to ping the LAN 2 port from either servers. Both are set up with crossover cables between each port on the card.

So from Server 1 if I ping 10.0.1.10 i get timed out
and from Server 2 if I ping 10.0.1.7 it also times out

I know the fault isn't with the second port on the cards because if I switch the subnets the opposite happens and I get time outs when i ping 10.0.1.9 from Server 1 and timeouts when I ping 10.0.1.6 from Server 2.

I'm sure there is some sort of basic network rule I'm forgetting here. I really cant get this to work

Can any1 shed any light on this issue? :S:S

oddjob62 · 28 Jun 2007 at 22:10

Why different subnet masks?

You do realise that
LAN 1 : 10.0.1.9
Subnet : 255.255.0.0
LAN 2 : 10.0.1.10
Subnet : 255.254.0.0

means the LANs are on the same subnet.
Ping will go down the higher priority interface (i think)

EDIT: actually it may always go down the 255.255.0.0 interface as that will be the more "specific" subnet mask. I can't rememeber which way Windows networking does things

bluestreak101 · 28 Jun 2007 at 22:18

why have the setup? most dual port cards I have used only work over one port when doing any type of data transfer in this type of config.

if your using windows I suggest bridging the two networks on both machines, it will force both ports to have the same IP on both machines i.e.

Machine 1:

10.0.1.6 255.255.0.0

Machine 2:

10.0.1.9 255.255.0.0

This will make it much easier to use and you will definatly be able to ping one another. Though you wont see any real gain tbh.

I personally have only use dual port cards for pcs acting as a firewall for my whole network (before I got a friewall box)

Tui · 29 Jun 2007 at 07:27

Just to clarify the other posts, your IP addresses and masks means that LAN 1 is 10.0.X.X addresses and LAN 2 is 10.0.X.X and 10.1.X.X addresses. This means they overlap.
Normal routing tables order the networks starting with the most number of bits for the network, so your machines will expect any 10.0 address to be on LAN 1 since it use 16 bits, instead of LAN 2 which is 15.

What are you trying to achieve here?
Since you're connecting the machines point to point, each port needs to be on its own network, for example
LAN 1 Server 1 10.0.0.1/255.255.0.0, Server 2 10.0.0.2/255.255.0.0
LAN 2 Server 1 10.1.0.1/255.255.0.0, Server 2 10.1.0.2/255.255.0.0

Or, to use a single IP address on each machine, configure the ports for link aggregation (802.3ad) rather than bridging them. All you'll get here is resilience, so that if a port or copper fails for one link then the other is still available.