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multiple IPs same NIC same subnet advisable?

Mike Patterson
Frequent Advisor

multiple IPs same NIC same subnet advisable?

We've built 3 HP-UX 11.31 systems on 3 BL860c blades for our Oracle DBAs who have installed Oracle 11g RAC there.

Each blade has 4 onboard NICs (we'll add a mezzanine card later to add APA).

Per our Architect's specs, on each blade, we have:
IP 1 in 192.168.204.x subnet on lan0.
IP 2 in 10.xx.xx.xx subnet on lan1
IP 3 in 192.168.75.xx subnet on lan2
IP 4 in 192.168.75.xx subnet on lan2:801
(this last "VIP" floating IP is automatically configured by Oracle RAC)
No IP on lan3

Problem symptom: we have seen packet loss pinging IP3 on one system from another RAC node and IP4 (VIP floater) transferring to another node intermittently.

Basic question: is it advisable to allow Oracle to configure IP 4 on 192.178.75.xx network on lan2:801 in the same subnet as IP 3?
6 REPLIES
Alzhy
Honored Contributor

Re: multiple IPs same NIC same subnet advisable?

"Basic question: is it advisable to allow Oracle to configure IP 4 on 192.178.75.xx network on lan2:801 in the same subnet as IP 3? "

I don't think you can even assign a different LAN / network address to a VIP than its non-VIP physical's IP.

So yes.

Check your netmasks though.
Hakuna Matata.
Mel Burslan
Honored Contributor

Re: multiple IPs same NIC same subnet advisable?

Just to correct Alzhy's misconception, you *can* configure the interface to a different subnet if your network infrastructure and networks admins do their portion of the task properly. Most modern blade servers if not all, support what-so-called VLAN trunking or VLAN Tagging, which enables running more than one network on any given physical interface. But is is no longer straight forward. One needs to work hand in hand with the network infrastructure people as the configuration is anything but trivial.

So, short answer, anything is possible but proceed with extreme caution.
________________________________
UNIX because I majored in cryptology...
Alzhy
Honored Contributor

Re: multiple IPs same NIC same subnet advisable?

Mel,

I am just folowings what our venerable Network Team told us.

So ye saying that if lan900 is 10.10.10.100, I can have lan900:1 as 192.168.10.100 ?

Yours truly.
Hakuna Matata.
Doug O'Leary
Honored Contributor

Re: multiple IPs same NIC same subnet advisable?

Hey;

>>So ye saying that if lan900 is 10.10.10.100, I can have lan900:1 as 192.168.10.100 ?

No; that you can't have. The multiplexed IPs have to be on the same subnet as the initial one assigned to the card.

Doug

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Senior UNIX Admin
O'Leary Computers Inc
linkedin: http://www.linkedin.com/dkoleary
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Alzhy
Honored Contributor

Re: multiple IPs same NIC same subnet advisable?

That is what I thought too doug.. thanks.

Well Mell?
Hakuna Matata.
rick jones
Honored Contributor

Re: multiple IPs same NIC same subnet advisable?

One most certainly can configure multiple IPs, in different IP subnets on top of the same physical NIC. Heck, one can even configure multiple physical NICs with IPs in the same IP subnet, although it does lead to complications in getting traffic flowing where one may normally expect it to flow. (perhaps necessitating static route entries and/or manipulation of the ip_strong_es_model setting in ndd)
there is no rest for the wicked yet the virtuous have no pillows