Friday, April 15, 2011

WOL Directed Broadcast Configuration on Cisco Layer 3 Switches

Use directed broadcast to configure the Wake On LAN (WOL) application on Cisco L3 switches. In our case we had the WOL servers connected to VLAN 1 (10.1.20.64 and .65). They are used to wake client computers on all other private VLANs. Here's the working example for our test case with clients on VLAN2:

access-list 180 permit udp host 10.1.20.64 any 
access-list 180 permit udp host 10.1.20.65 any

interface Vlan1 
ip address 10.1.0.10 255.255.0.0 
ip helper-address 10.2.255.255 
interface Vlan2 
ip address 10.2.0.10 255.255.0.0 
ip directed-broadcast 180 

Note that the helper address sends the WOL broadcast to all destination subnets that are specified there (in our case to the 10.2.0.0/16 subnet) but you control what lands up on the destination VLAN with the directed broadcast command and an acl. It works if you use a supernet in the helper address command to cover all your destination networks.

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