04-06-2009 06:03 PM - edited 03-06-2019 05:02 AM
Hi All, we have a software application that we are trying to use for WOL. It says that its forwarding using port 7725. I thought I had all my ducks in row. I configured my access list, tagged the the SVI with the ip directed broadcast, and added ip forward-protocol udp 7725. However when I try my software app I can never get outside of the subnet that the server is connceted to. Both the server and one of my data networks share the same subnet however, I have a handful of other subnets that I need to forward this port. Here is a partial config of "DO-Switch" which has the server and some hosts in VLAN 1 then another switch's config that has serveral other VLANS that need WOL.
***DO-Switch***
interface Vlan1
ip address 10.1.0.1 255.255.240.0
ip directed-broadcast 101
no ip mroute-cache
!
interface Vlan252
description Wireless WAN B Layer3
ip address 192.168.252.2 255.255.255.0
ip directed-broadcast 101
ip pim sparse-dense-mode
!
router eigrp 100
redistribute static
network 10.0.0.0
network 172.16.0.0
network 192.168.249.0
network 192.168.251.0
network 192.168.252.0
network 192.168.253.0
network 192.168.254.0
no auto-summary
!
ip classless
ip forward-protocol udp 7725
ip route 0.0.0.0 0.0.0.0 192.168.254.1
no ip http server
!
!
access-list 101 permit udp host 10.1.0.6 any eq 7725
----------------------------------------------------------
***Core-Switch***
interface Vlan3
ip address 10.3.0.1 255.255.240.0
ip helper-address 10.2.0.4
ip helper-address 10.2.0.13
ip directed-broadcast 101
ip pim passive
!
interface Vlan4
ip address 10.4.0.1 255.255.240.0
ip helper-address 10.2.0.4
ip helper-address 10.2.0.13
ip directed-broadcast 101
ip pim passive
!
interface Vlan252
description Wireless WAN B Layer3
ip address 192.168.252.1 255.255.255.0
ip directed-broadcast 101
ip pim passive
!
router eigrp 100
no auto-summary
eigrp stub connected summary
network 10.0.0.0
network 192.168.251.0
network 192.168.252.0
network 192.168.254.0
!
ip classless
ip forward-protocol udp 7725
no ip http server
ip http secure-server
!
no logging trap
access-list 101 permit udp host 10.1.0.6 any eq 7725
Ip address 10.1.0.6 is the WOL server
thanks for the help,
Mike
04-07-2009 04:02 AM
Hello Mike,
I think you should use
ip helper-address 10.x.y.255
the command you have used is declared to convert a directed broadcast to a broadcast but you need to propagate the broadast from the subnet where the server is to all the other client vlans
int vlan 1
ip helper-address directed-broadcast-subnet1
ip helper-address directed-broadcast-subnet2
...
ip helper-address directed-broadcast-subnetN
see
http://www.cisco.com/en/US/docs/ios/ipapp/command/reference/iap_i1.html#wp1052696
if the server sends out broadcast packets to make them reach the other subnets you need to use ip helper-address command for each client vlan under the SVI that processes the server traffic
Hope to help
Giuseppe
04-07-2009 07:55 PM
Thanks for the reply, where should I add the "ip helper-address 10.x.y.255 " command to every SVI with the exception of Vlan 1? Will this interfere with the other "ip helper-address" commands that I have already set up on the SVI for DHCP? If thats the case do I still need my Access-list and "directed broadcast" command?
thanks,
Mike
04-07-2009 10:34 PM
Hello Mike,
the commands I have suggested need to be added only to the vlan where the server is connected to, that is vlan1 in your scenario.
My suggestion starts from the guess that the server is probably sending packets with a broadcast destination.
So its action is currently confined only on the vlan/subnet where the server is connected to.
So in my opinion you need to add the ip helper-address commands only to Vlan1
helper-address command instructs the router to convert a non routable broadcast to a routable unicast or directed broadcast that can reach other IP subnets.
Hope to help
Giuseppe
04-08-2009 03:36 AM
Mike:
Keep a few things in mind as you configure this:
1.) The ip forward-protocol command alone does nothing. You need the ip helper-address command, too. The helper address command lets the router interface know that it will be receiving a UDP broadcast from a directly connected client and that it should repackage it as either a directed broadcast to a specific destination subnet or a unicast to a specific machine.
By default, the helper address allows 8 different UDP-based applications to get forwarded, excluding WOL. That is why you need the ip forward-protocol command: to add that UDP-based application to the list of forwarded applications.
2.) The ip directed-broadcast command should be applied to the vlan interface that is expected to receive the directed broadcast from the sending/forwarding router. The directed broadcast is a tool sometimes used by hackers to launch a denial of service attack, so routers block directed broadcasts that are destined for directly connected hosts hanging off the interface.
So, you are dealing with broadcasts in 2 directions - the send side, which is why we use the helper address and the forward protocol commands, and the receive side, which is why we use the ip directed broadcast command.
HTH
Victor
04-11-2009 01:37 PM
Thanks both you. It's much more clearer now. Identifying the UDP port it was broadcasting was a bit of a pain but, once I had that any both of yours info got it knocked out.
thanks again,
Mike
04-11-2009 03:19 PM
Mike:
Congratulations. Glad we could help.
Thanks for the rating...
Victor
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide