topic Re: Virtual IP address in Operating System - HP-UX

Virtual IP address

malay boy — Mon, 12 Sep 2005 18:12:55 GMT

Hi,
Just wondering whether can we have 2 port with ip address (10.10.10.10 and 10.10.10.12) also having a virtual ip address (10.10.10.11) running on both of them(only one active).

Meaning there will be one port ( 10.10.10.10 ) also with ip address ( 10.10.10.11) and when this port dies , the next port will take the virtual ip . ( so the next port will be become 10.10.10.12 and 10.10.10.11 ).

Can this be done ?.If yes, what software do I need ?.

Normally in MC Service Guard, we have 2 port with no IP address but will have virtual ip address running on either of this card.

Regards
mB

Re: Virtual IP address

Thayanidhi — Tue, 13 Sep 2005 00:53:20 GMT

Hi,
You cannot have two IP addresses in the same subnet belongs to different i/f card in the same system. Means you cannot have IP's belongs to same subnet assigned to different physical LAN cards. Though hp-ux allows this, this will lead to lot's of problem. If you want to use multiple physical interface concurrently then go for APA (auto port aggregation) which would combine multiple physical in to single logical i/f. If you want additinal IP's you can always assign virtual IP's.
If you want switch the IP's use Mc/SG. Even single node Mc/SG can do a LAN switchover.

Regds
TT

Re: Virtual IP address

Mel Burslan — Tue, 13 Sep 2005 00:58:57 GMT

The answer is, No what you are trying to do can not be done.

The main problem with your configuration is, you have two interfaces within the same subnet which is a big NO-NO in hpux.

The nature of the virtual IP addressing is, the virtual IP address has to be in the same subnet as the actual IP address of the interface. Since you can not have two actual/physical IP addresses in the same subnet per hpux requirements, you can not float a virtual ip address belonging to one interface, seamlessly to another live interface.

So, the only way to float a virtual IP is either using Auto Port Agrregation software with two physical interfaces in Active/Standby mode, or using ServiceGuard and using one active interface and the other one as a inactive failback interface.

Either solution will cost you some money as neither APA not MCSG is free.

Of course, if you can develop your own scripts you can write your own failover code yourself. It is not rocket science and if the only thing you need is to move the ip back and forth between two interfaces, it is not complex at all.

Hope this helps

Re: Virtual IP address

Ivajlo Yanakiev — Tue, 13 Sep 2005 02:30:44 GMT

not supported way :)
make shell script that check lan card and if it go down config next port with same IP address