WOL needs multiple IP Helpers

[Patrick McDonnell]

Hi, I have a scenario where a customer requires the use of WoL over the WAN to waken PCs located on 100 remote sites. There are two servers sending the magic packets located in a data centre. One of these can use subnet directed broadcasts the other just broadcasts.

Questions are as follows

• •1. With the server that doesn’t support subnet directed broadcasts I believe that I require IP helper addresses to be configured on the gateway, one for each remote subnet broadcast address – is this correct? If so, is there a limit to the number of IP Helpers that should be configured – we have 100 remote sites and this seems impractical as I read somewhere that 16 was the recommended maximum for IP helpers. The server is supported by a third party and any changes to this are not feasible.
  
• •2. The second server that supports subnet directed broadcast should not need any IP Helpers – is this correct?
  

The gateway for these servers is a Cisco ME3600x Metro switches (ME-3600X-24TS-M) supported by another third party.

Any direction on this would be greatly appreciated. Thanks

[Richard Burts · Accepted solution]

1) Yes for the server that does not support subnet directed broadcast you will need a helper address for each unique remote subnet. I am not aware of a specific restriction on the number of helper addresses but will admit that I am a bit concerned about the impact of trying to run 100 helper addresses on ME-3600X.

2) if the other server does support subnet directed broadcast then you would not need any helper addresses for this server.

Be aware that if you are sending directed broadcasts for WOL that you will almost certainly have to configure each of the remote subnet interfaces to permit forwarding of directed broadcast, since this has been disabled on Cisco gear for quite a while.

HTH

Rick

[Patrick McDonnell]

Thanks Richard. It is good to get confirmation and clarity on this. Patrick

[Richard Burts]

Patrick

Glad to be of help. Good luck with this. When you get it done post back to the forum and let us know how it went.

HTH

Rick