ATTN: Angela - PCNS and The Dangers of Broadcasting

[Anonymous user]

Referencing an answer from another thread: http://forums.apc.com/message/14380#14380

You said: "you don't need to do anything special to tell the PCNS software to check for broadcasts or anything. just install it and give it the IP address of the management card that it needs to look for broadcasts from."

Here's my dilemma: The folks that set up the server room I support should be SHOT !

There are 4 big UPS units, each with one NMC.  They are all on their own network segment : like 10.11.12.(101, 102, 103, 104) with an InfraStruXure Manager running at 10.11.12.100.

There are more than 50 machines in each "block" (i.e.plugged into one UPS), so not every server can register with the NMC.

The concern is this: If there are any PCNS clients running in "broadcast mode" (not registered with its local NMC), the shutdown sequence will be triggered on ALL machines by a signal from ANY ONE NMC because there is no grouping by network segment.

And now for the Gazillion Dollar Question: Your response makes me think that a PCNS client in broadcast mode can be told to only pay attention to one NMC by providing its IP, even if it is not registered to it.   If this is true, then we can protect everything with PCNS without completely rebuilding the network architecture.  If this is not the case, then we are back in the same hole as when I started this thread, and thanks for looking.

[BillP]

Does this help explain? http://www.apcmedia.com/salestools/BKIR-6QWKC5/BKIR-6QWKC5_R2_EN.pdf

This is also more up Bill P.'s alley. I discussed it with him and we don't believe it will be a problem for you.

When you install PCNS on the clients that will get a broadcast, you still need to register them with a particular NMC's IP, even though PCNS won't add it's client's IP into the NMC's list. Thus, it still knows what IP to pay attention to. I can't see a way that it will let you install PCNS without inputting a particular NMC's IP.

Anyway, I think the PDF is helpful to assist in understanding.

If you have any other questions, let us know.

[voidstar_apc · Accepted solution]

Hi ygor,

The PCNS broadcast data includes the IP address of the NMC the data originates from. You can verify that with Wireshark... you'll see something like "PC=". PCNS clients will only accept data originating from the NMC they're associated with regardless of whether it's direct unicast, broadcast from the NMC, or even broadcast from another PCNS client. Data received from other NMCs get dropped and will not cause a shutdown.

Hope that helps.

[Anonymous user]

I had gone thru that document, but I was under the impression that the only thing containing the broadcast was the network segment.  There is no mention in the documentation (that I found) that points this out.

[Anonymous user]

Many thanks !