IP Directed-Broadcast

[e-bittlinger]

I have an application at our home office that broadcasts data(directed broadcasts) to a couple of our remote offices. I realize I need to use the ip directed-broadcast command so that the broadcasts will not be stopped by the router. Does anyone know if this command only needs to be on the initial interface or does it need to be on every interface in the path?

[thisisshanky]

I would believe it will have to be on every router on the path. What protocol is being used ? UDP or TCP?? If its UDP you can create a helper-address to forward the broadcast that you receive as a directed broadcast and then specifically forward the desired UDP port number.

ip helper-address

ip forward-protocol udp

[e-bittlinger]

Thanks for the comment shanky. I did think of using the helper-address as plan B. The app is using UDP.

[Richard Burts]

Actually it does not need to be on every interface on the path. The only interface where it needs to be is the interface connected to the destination.

The logic for that is fairly clear. Only devices which have the subnet mask of the destination can determine whether the destination address constitutes a broadcast or not. No device on the path can accurately determine whether is is a directed broadcast because no device on the path has the destination subnet mask.

HTH

Rick

[e-bittlinger]

Rick

Thanks for your reply. You are correct. I just finished testing that in a lab environment. Again thanks.