AIX

Hi Guys,

there are a few restrictions regarding HACMP subnets. One of them is that all subnetmasks should be the equal.

Is there a reason for this?

thx>RaBa

Why do you ask?
Where did you see this restriction?
What version of HACMP or Power HA are you referring to?
Did you think they just published this restriction in for a laugh?
;0)

As it is i am not aware of this suggestion being in effect. Still, HACMP (5.x) is not my area of expertise. Could you please cite the source where you have read/heard this.

bakunin

@dukesdd
Hi,

@dukesdd
- because I have a question
- see redbooks below and many more HACMP related books
- version 5.1 and up
- usually restrictions keep you from laughing

it's in redbook
"Certification Study Guide - pSeries HACMP for AIX" sg246187.pdf page 164:
"Verify that all boot, service and standby addressers have the same
subnetmask and that standby addresses will not be on the same subnet as
the boot and service addressers."

and "PowerHA Cookbook" sg247739.pdf page 173:
"Subnet requirements will vary depending upon the configuration chosen
(IP Address Takeover -IPAT- via replacement or alias). However, all the
communication interfaces configured in the same PowerHA Network Name must
have the same subnet mask, while interfaces belonging to different PowerHA
Network Names can have either the same or a different network mask."

Hi Raba,

of course you need corresponding subnet masks for all serviceadresses (subnetmask1) and for all boot adresses (subnetmask2) and for all persistent adresses (subnetmask3) across your clusternodes - but that does NOT mean that subnetmask1, 2 and 3 have to be the same. In my clusters, they're pretty different between service and boot - and it still all works perfectly fine.

Kind regards
zxmaus

That quote is too short. Be omitting the context you will fail to understand what is going on.
Ah, there it is. You found it yourself but unfortunately you overlooked what actually stands there. Problem here seems to be that you are not aware of what an HACMP Logical Network is. Those networks in the cluster configuration get a distinct name. Several subnets can be combined in such a Logical Network but to stick to the rule those subnets must share the subnet mask. You can have more than one Logical Network defined in your cluster though and other Logical Networks may or may not have different subnet masks then.

hi,

thanx for you're reply. Below is another note from PowerHA cookbook sg247739.pdf.

"Note: AIX allows IP aliases with different subnet masks to be configured for an
interface. However, PowerHA will use the subnet mask of the base IP address
for all IP aliases configured on this network interface."

From this I think it means that although the service address has a different subnetmask, Power HA will use the the subnetmask of the base IP address. Base IP address is the boot address here