CA Wake-on-LAN directed broadcast question

mmertens · ‎02-23-2010

My customer has a CA DSM performing Wake-n-LAN across some Cat6500s configured with L3. WoL doesn't work to remote device after they've been down for more than 4 hours. I've configured the network as prescribed in the below document to meet the IP directed-broadcast support requirement :

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_example09186a008084b55c.shtml

but it is still not functioning. I sniffed the magic packet and I see: a packet with

SMAC=server, SIP=server, DIP = remote client, and DMAC =00:00:0c:07:ac:10 ("All HSRP Routers"), dest UDP port =7. I see one packet, and that is it.

Config; (Server= 172.16.202.9, 172.16.202.10, 172.16.202.15, Client VLAN=172.16.114.0/23

ip forward-protocol udp echo

Extended IP access list 130
    10 permit udp host 172.16.202.9 172.16.114.0 0.0.1.255 eq echo
    20 permit udp host 172.16.202.10 172.16.114.0 0.0.1.255 eq echo
    30 permit udp host 172.16.202.15 172.16.114.0 0.0.1.255 eq echo

interface Vlan (For Clients)
ip address 172.16.115.252 255.255.254.0
ip helper-address 172.16.202.174
no ip redirects
ip directed-broadcast 130
no ip proxy-arp
ip flow ingress

Server VLAN where WoL originates:

int vlan (server)

ip helper-address 172.16.115.255

My question is: Is the "ALL HSRP Routers" Multicast dest MAC be what I should expect to see from CA DSM WoL Server? The problem appears to be WoL NOT working after the PC has been off for more than 4 hours and ARP caches have aged out on L3 Cat6500.

THANKS!

Giuseppe Larosa · ‎03-01-2010

Hello Mike,

this packet:

>> SMAC=server, SIP=server, DIP = remote client, and DMAC =00:00:0c:07:ac:10 ("All HSRP Routers"), dest UDP port =7.

is correct but the server is trying to reach the client using its known IP address.

the setup described in the document you have linked is thought to convert a broadcast to one or more directed broadcast (one for each client vlan/IP subnet)

A unicast packet does not need to be converted, it can be routed normally and it is what you see: until the multilayer switch handling the client Vlan knows the destination MAC address in the ARP table, it is able to forward the unicast IP packet with DIP = remote client.

The server should send out packets with DMAC = FFFF.FFFF.FFFF DIP = 255.255.255.255 to trigger the conversion.

The packet should then contain the MAC address of the PC to be awaked in its payload, the packet is first converted to a directed broadcast and then sent out in final segment with DMAC = FFFF.FFFF.FFFF target device detecting its own MAC address in the payload should be awaked

Hope to help

Giuseppe

mmertens · ‎03-01-2010

Hi,

Thanks for responding.....I got this to work last week by configuring, per the Cisco doc, and CA DSM had to be globally configured from "unicast" to "unicast/broadcast". We had contacted CA and they had notified us of the configuration option's location. After that, the packet on the server VLAN had a dest IP of the target subnet's network broadcast, but still had the dest MAC-address of multicast "All HSRP Routers". Interesting- the router processes and propogated across L3. The packet on the target subnet coming from the L3 switch had a dest MAC and IP of broadcast. And the UDP port 7 packet's payload contained the mac-address of the client machine to be awoken- and it worked! Very interesting about the multicast packet on the server VLAN. I wonder how CA gets it to work on non-Cisco networks??!! (Not my problem).

Thanks for the response!