Different IP adresses on the same Ethernet port.

[Simone Benzi_1]

Hello everybody,
Is it possible to configure two different IP addresses belonging to two different subnets on the same Ethernet card?

I mean a netconf file like this:

INTERFACE_NAME[0]="lan0"
IP_ADDRESS[0]="192.170.121.84"
SUBNET_MASK[0]="255.255.255.0"
BROADCAST_ADDRESS[0]=""
INTERFACE_STATE[0]=""
DHCP_ENABLE[0]=0

INTERFACE_NAME[1]="lan0"
IP_ADDRESS[1]="192.170.100.71"
SUBNET_MASK[1]="255.255.255.0"
BROADCAST_ADDRESS[1]=""
INTERFACE_STATE[1]=""
DHCP_ENABLE[1]=0

where lan0 is the same: /dev/lan0

Thanks a lot!

Simone

[Ralph Grothe]

Hi Simone,

wonder how you would use this NIC?

Do you use some sort of Y-cable? ;-)

[Robert Binkhorst · Accepted solution]

Hi Simone,

Using lan0 twice will give you problems. How will HP-UX know which one is which if you specify lan0? You can make multiple virtual addresses by adding :1, :2 and so on.

So this should work:
INTERFACE_NAME[1]="lan0:1"
IP_ADDRESS[1]="192.170.100.71"
SUBNET_MASK[1]="255.255.255.0"
BROADCAST_ADDRESS[1]=""
INTERFACE_STATE[1]=""
DHCP_ENABLE[1]=0

HTH,

Robert

[Simone Benzi_1]

Yes! I'll use lan0:1 lan0:2 and so on...
Since the subnets are different could it bring any problem?

[Robert Binkhorst]

Hi,

Oeh. Missed that one! Subnets need to be the same as far as I know. You can try this, make sure that your traffic can be routed, I don't see any other option I'm afraid...

Let me know how this works out?

Robert

[MarkSyder]

I don't think the different subnets will cause a problem. Presumably the box will be acting as a router between two subnets?

Mark Syder (like the drink but spelt different)

[Sarvesh A Dhuri]

Hi

You create subinterface like lan0:1 ,
and assign the IP address to this interface , you can assign the IP address of other subnet . I hope you must have shortcircuited the two subnet, which is not a good practice.

[KapilRaj]

It is not a bad idea to assign two IP_Addresses to an interface as far as they are in the same logical network (L3).

Looking at your IP & Subnet mask I can see they are of two diffrent TCP/IP network !. How will you wire a single Ethernet interface to two Physical Networks ?.

What is your requirement here?.

Regds,

Kaps