Wake-On-LAN (WOL) Network Configuration

He are all the details to implement Wake-On-LAN with a Brocade Router across several subnets.

Background information

Wake-on-LAN (WOL) has been used for years as a way for network administrators to turn on PCs remotely. It works by creating and issuing a specially formatted network packet (often referred to as a “magic” packet, and typically generated via a software utility) containing a target PC’s MAC address.

WOL is based on the principle that when the PC shuts down, the NIC still receives power, and keeps listening on the network for the magic packet to arrive. This magic packet is mostly based on UDP. In our case we will use the utility from SolarWinds that will send a UDP packet on port (7) to trigger the wake up of a remote machine.

Equipment used

  • Brocade FCX that runs FCXR07100a.bin (Router)
  • Brocade FCX that runs FCXS07100a.bin (Switch)
  • Freeware Wake-On-LAN utility from SolarWinds

Considerations

Before deploying WOL across several subnets, first ensure your desktop can be waken remotely.

  • Check your BIOS settings and ensure Wake-On-LAN is enabled
  • Check your NIC Advanced Settings and ensure that Magic & Directed Packets are accepted
  • Connect your WOL server and your desktop/laptop client to the same VLAN
  • Invoke Wake Up PC from SolarWinds
  • If the PC wakes up you can go further and configure it across several subnets

Network Diagram


Configuration

  • Router (inter-VLAN)

!
vlan 10 name server_vlan by port
tagged ethe 1/1/10
untagged ethe 1/1/1
router-interface ve 10
!
vlan 20 name user_vlan20 by port
tagged ethe 1/1/10
router-interface ve 20
!
vlan 30 name user_vlan30 by port
tagged ethe 1/1/10
router-interface ve 30
!
!
ip forward-protocol udp echo
interface ve 10
ip address 192.168.10.1 255.255.255.0
ip helper-address 1 192.168.20.255
ip helper-address 2 192.168.30.255
!
interface ve 20
ip address 192.168.20.1 255.255.255.0
!
interface ve 30
ip address 192.168.30.1 255.255.255.0
!

  • Switch

!
vlan 10 name server_vlan by port
tagged ethe 1/1/10
untagged ethe 1/1/1
!
vlan 20 name user_vlan20 by port
tagged ethe 1/1/10
untagged ethe 1/1/2
!
vlan 30 name user_vlan30 by port
tagged ethe 1/1/10
untagged ethe 1/1/3
!

Explanation

As soon as your inter-VLAN routing is configured correctly, there are only 2 commands to add so that your machines on different subnets/VLANs can be waken remotely by a WOL server. The Brocade FastIron Router does not forward by default requests for UDP applications. You can enable forwarding support for a specific port (forward-protocol). Then you have to specify the port used by your application. In our case, SolarWinds uses UDP packets on port 7 (echo).

The second step is to configure an helper address on the VLAN of the WOL server to be able to join the subnet of your clients. The aim is to foward packets from the WOL server to each client subnet. Thus you have to specify the broadcast address of each client network to make it work. This is the only way to send a packet to a machine that is asleep. Indeed, in this situation, the PC will not be able to answer to ARP requests, since it does not own its IP at this time.

  • Specify the protocol (udp) and port (7) to be forwarded:

ip forward-protocol udp echo

  • Enable forwarding of WOL packets to clients

ip helper-address 1 192.168.20.255

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