VLANs in hpux 11i

[hp_user_1]

Hi,

I like to use a gigE adapter to establish 4 virtual networks going to a single network switch. Can anyone provide pros and cons, and how to do it in hpux?
Thanks

[Steven E. Protter]

HP-UX will operate perfectly well in a VLAN environment. Broadcast x windows will not work for clients outside the VLAN the server is sitting on.

You should however set up the VLAN's on the switch.

So long as the switch forwards the traffic from other VLAN's to this one the server is on, the HP box will operate properly.

I do not see a need to configure all four vlan's as virtual ip addresses in /etc/rc.config.d/netconf

I'm not certain it could be done anyway, but I don't see what it gets you.

SEP

[Mel Burslan]

First of all, the use of acronym VLAN is totally inappropriate here. VLAN term is used in the networking world to separate the subnets served by the same physical switch into different subnets (I know this is not exactly how you read it in network design and iplementation books but take it for the lack of a better and short explanation)

What you are trying to do is called virtual IP addressing, which is not rocket science.

lets say your interface has an IP address of 192.168.100.10 with a 24 bit mask (255.255.255.0 that is) Your other virtual IP addresses can be anything in the 192.168.100.xxx subnet. The catch is, unless all the IP addresses are in the same subnet, your networking device, i.e., gBit switch port, will not know how to access this IP address. It will be like putting a foreign IP address in a subnet where it does not belong to.

implementation is also easy. To configure a virtual interface on the fly:

ifconfig lan1:1 inet 192.168.100.11 netmask 255.255.255.0 up

will bring up the new IP into life

in your /etc/rc.config.d/netconf file, the same interface, i.e. lan1:1 will be another instance like:

INTERFACE_NAME[1]=lan1:1
IP_ADDRESS[1]=192.168.100.11
SUBNET_MASK[1]=255.255.255.0
BROADCAST_ADDRESS[1]=
INTERFACE_STATE[1]=up
DHCP_ENABLE[1]=0


hope this helps

[hp_user_1]

Thanks for the answers. So that means my first IP will be assigned to lan0:0, second to lan0:1, third to lan0:2 and fourth to lan0:3. Is my understanding correct ?
Regards

[Mel Burslan]

Assumption is correct although sequential order is not mandatory. You can have lan0:2 then lan0:7 etc... as long as you know what you are doing and which IP you assigned to which virtual interface. And again, I can not emphasize this enough, all IP addresses, real or virtual, assigned to this physical device, needs to be in the SAME SUBNET !!!

[hp_user_1]

My 4 IPs are on different subnets. Can't it be done?

[Mel Burslan]

Unfortunately not due to the fact that one physical switch port can be a member of one VLAN hence one single subnet. If anyone has come up with a different solution, I really would like to know about it myself too.

[Duncan Edmonstone · Accepted solution]

Does your switch actually have 4 seperate VLANs on it, or just 4 seperate IP subnets.

If its just 4 seperate IP subnets your going to struggle, as Mel has laready indicated.

If you actually have 4 seperate VLANs the you may be able to get it working if your switch is supported.

Download and install the patches that enable VLAN support:

http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=VLAN

Read the manual on how to configure:

http://docs.hp.com/en/T1453-90001/T1453-90001.pdf

I suspect you will have to review all this with your network admins...

HTH

Duncan

[Jay Kidambi]

FYI

HP-UX 11i supports explicit VLAN tagging. This feature allows you to configure multiple VLANs on a single NIC on an HP-UX system. You could then connect the NIC to a switch port that supports VLAN tagging (most switches do). All you have to do is configure all those VLAN IDs on the switch port as well. Switch ports typically allow you to configure one 'untagged' VLAN (this is the VLAN ID associated with untagged frames) and multiple tagged VLANs (VLAN association is made based on the explict tags the end-station transmits in the ethernet header).

Switch-based VLANs, which most people are familiar with, make implicit VLAN association based on attributes such as port number, IP subnet, etc. But with HP-UX VLANs, the end-station transmits frames with explicit VLAN tags, so all the switch has to do is to forward it to an appropriate port. Of course if the destination port doesn't support VLAN tagging, you must configure the switch to strip the VLAN tag before forwarding.

One of the advantages of HP-UX VLANs is that you can use basic layer2 switches to implement VLAN trunking (which means a single port can belong to more than one VLAN). If you have external routers to route between the VLANs, you don't need layer3 or more complex layer2 devices to implement VLAN trunking.

More information about HP-UX VLANs can be found at the following location.

http://www.hp.com/go/vlan

HTH,
Jay