Wake-on-LAN (WOL) allows a computer to be turned on or awakened by a network message.

The message is usually sent by a program executed on another computer on the same local area network. It is also possible to initiate the message from another network by using subnet-directed broadcasts.

WOL packets are sent to either UDP port 7 or 9.

The goal is to send a WOL packet from one PC to another.

Consider the topology below:

PC-A  172.27.199.114   ------- SW ------- 172.27.199.125  (ge000)  SRX  (ge001)  10.2.2.1  ---------  10.2.2.2  PC-B
                                                       |
                                                       |
                                                    PC-C  172.27.199.125

Here, the goal is to send a WOL packet from PC-A to PC-C and PC-B.

When a packet is sent from PC-A to PC-C, WOL packets are sent to the broadcast IP address 172.27.199.255, and configuration of SRX is not needed.

When a packet is sent from PC-A to PC-B, SRX is traversed. The packet is sent from PC-A to the broadcast IP address 10.2.2.255. SRX knows that the 10.2.2.0/24 subnet is reachable through the ge001 interface, but, because the destination is a directed broadcast address, the packet is dropped by the SRX. This is the default behaviour.

To allow the WOL packet on the broadcast IP (10.2.2.255) in the scenario above to be forwarded by the SRX, the following configuration is needed on the ge001 interface:

root@210-1# show interfaces ge-0/0/1
unit 0 {
       family inet {
               targeted-broadcast {      <<<<<<<<<<
                         forward-and-send-to-re;
               }
              address 10.2.2.1/24;
      }
}

For more information on targeted-broadcast, click the links below:

• Understanding Targeted Broadcast
• Configuring Targeted Broadcast

Please note that the above feature is supported only on SRX branch devices.

Symptoms : Rephrased about the destination as directed-broadcast address , SRX will drop the packet by default