Make MEMCM WOL succeed on large subnets
We have problems waking up clients with subnet directed broadcast on large subnets.
We can see that one MEMCM server can issue 6-7.000 WOL requests in one second.
Unfortunately not all targeted machines are powered on, when MEMCM issues this massive amount of WOL packages.
Network traces have shown, that all WOL packages arrives to the subnets, but many machines fails to power on.
There can be many reasons for this, UEFI config, network topology and so on, but we have found another problem, that might explain this issue.
We have tried to send a WOL package to 250 machines on one subnet with a tool provided by Microsoft. The program sends all WOL packages in a very short time, like MEMCM, and many of them fails.
We have created a Powershell script that wakes up one computer at a time. This script runs for 100 seconds to wake up 250 machines, but all machines gets started!!!
That leaves us with the conclusion, that this error is not caused by Network or Client configuration, but maybe because of limited processing power or cache size in the network cards that should evaluate these WOL packages.
MEMCM can limit the number of WOL requests in one batch to 1000, but that is way too many for the clients to handle.
We need an option to define a number of milliseconds between WOL requests, or something like that.
Respond from our case with MS:
I would call this an error in the product, when the WOL function is incapable of waking up clients, so I hope for a fix, but we have created this UserVoice in order for other users to attract the attention of Microsoft to this problem.
René Kierstein commented
We will test this when we're on 2010. Hopefully in Q1-2021
Bent Buhl commented
It looks promising.
What happens, if all clients are powered off on the subnet:
2. A subnet directed broadcast is targeted a single client on the subnet, and when that client gets online, the rest of the machines is woken up with the client notification channel.
If 1. is the answer, we need a wake up client online 24x7, which will complicate things, and make little sence in small subnets.
George Simos commented
In 2010 build there is a new option that allows you to utilize turned on devices in a subnet to wake up their siblings.
It uses the notification channel and not directed broadcasts.
Can you try and let us know how it works for you (so we know if it is a good solution)?
René Kierstein commented
I have also reported this via a frown in the MEMCM console