Wake on Lan (2023 version)

Danny Mainprize · ‎04-26-2023

I am running a full switching network. My cores are all 9504 and my access layers are all 9200 and 9300s. I have approx 50 vlans. All vlans can see and ping each other and there is nothing filtering traffic. Every guide I can find is from way back before 2010.

My question is how can I get wake on lan to actually work again? I have a central server on vlan 101 that has an inventory of all my machines, including mac addresses, on all my vlans. I would like that one machine to be able to wake up any workstation it has the proper information about regardless of the vlan it lives on.

Years ago it was IP helper-address and IP forward commands, but those don't exist in these new model switches. I have tried adding IP directed-broadcast without success. Each workstation has wake on lan enabled and is ready and waiting to receive the magic packet.

What am I missing?

Paul Chapman · ‎04-26-2023

Hi -

IPv4 WoL is characterized by a directed broadcast to a subnet with the target MAC listed 12 times in the payload. You should be able to validate this with a simple packet capture on the central server. Directed broadcast is disabled by default in current IOS versions, so you will need to add it on each SVI that services end hosts (not needed on the SVI that services the central server).

PSC

Flavio Miranda · ‎04-26-2023

Hi

I used to use Wake on Lan through the Internet in the past by targeting my home PC on UDP port 9. I believe it is still possible. Which means, no broadcast used.

https://hackernoon.com/wake-on-lan-through-the-internet-491817e2dd41

Paul Chapman · ‎04-27-2023

I didn't say anything about UDP or TCP. That is L4. Directed broadcast is L3, pure and simple. In a local LAN environment as described in the OP, L4 is completely moot.