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Wake on Wan Timeout

Last response: in Networking
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November 22, 2011 6:53:06 PM

Not sure which sub-category this goes under, so its here.

Ok, the problem I'm having is a Network issue not the computer hardware or the computer settings. I know this because it works flawlessly when testing it.

The problem is that if i wait a while (not sure how long) the Magic Packet doesn't work. It only works about 5 or 10 min after shutdown of the computer. Which leads me to believe its the network (although i could be wrong). I have tested and ran just about every idea i could, just to find out whats stopping it.

Im using 1 Motorola Modem, 1 Linksys Switch, and 1 Linksys Router.

The reason why i have and am using the switch is to give the server with WoL its own IP. And the router to share another IP to the other devices.

Here's the setup as followed:

Modem
|--> Switch
___|--> Server (IP1)(WoL)
___|--> Router (IP2)
______|--> PC
______|--> Wireless Devices
______|--> Consoles
______|--> TV

Edit:
Ok .. maybe it is a hardware issue. Just in case here is the hardware
Motherboard (With onboard Lan): ASRock AD525PV3
OS: Windows 7 64bit

More about : wake wan timeout

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November 23, 2011 12:52:51 AM

I believe the problem is hardware, but probably not the hardware you think. Here’s what I believe is happening.

When a request comes into the switch for the first time w/ the IP address of the Server, it doesn't know where the Server is located. So it broadcasts an ARP request w/ that IP address and waits for a response from the Server containing its MAC address. The switch then caches that information for subsequent traffic. However, that information isn't maintained indefinitely. When the Server eventually shuts down, it obviously won't respond to further network requests, and any further ARP broadcasts come back unacknowledged. At that point, any further attempt to reach the Server fails.

Ok, so you're now asking, well shouldn't it then just broadcast my magic packet across the switch? No. The switch isn't smart enough to treat the magic packet differently under those circumstances. The only reason it's working for those 5-10 minutes is NOT because the switch issued a broadcast of the magic packet, but simply because the Server received the magic (UDP) packet as it normally does, and it just happens to contain the magic packet. And so it wakes up. But that’s only going to work for as long the switch maintains the ARP entry for the Server.

If you had a managed switch, or perhaps the switch was part of a router where you could manipulate the ARP tables manually and make them permanent, that might be a solution. But using a simple switch, this is highly unlikely.

What you need is something that ensures your magic packet ALWAYS gets broadcast, so why not try a hub! A hub doesn’t use ARP, it just takes anything it receives and broadcasts it to all connected devices, leaving it up to those devices to work it out. Every device will eventually see the magic packet, but of course, only the Server will respond. This is one of those rare cases where a hub actually works better than a switch. To be honest, it’s not something I’ve actually tried, but I strongly suspect it would work.

Personally, I don’t use either a switch or hub for WOL. Using dd-wrt, I’m able to issue WOL requests from the WAN side and wake any PC at any time. It requires a small hack that’s explained on the dd-wrt website.

http://www.dd-wrt.com/wiki/index.php/WOL

So I don’t know if that would interest you, and whether you *need* a public IP for the Server for other purposes, or whether that was done only because of WOL. But it’s just something to be aware of.

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November 23, 2011 2:05:56 AM

thanks for the reply
Thank you for providing such a clean and useful amount of information.

So now I'm left with a new quest then. But first, which one?
I would like to expand on all the options, of course, i want the one that works best tho.

I noticed you said something about "...manipulate the ARP tables manually...", but du to the simplicity of these items (and your right) those items cant do that. I've dug and clicked right through all of it, but nothing. I would assume that i would have to buy a brand new device that has this capability.

Although... Getting just a hub sounds like it would be easier from the way you describe it. Do you mean replacing the switch with it or adding it after the switch and before the server? And if it is that easy... is there a cheap, but reliable, hub out there. I say that because, if i go looking around the internet for a "good" hub i can never tell. These days you really almost don't know what your buying until its in your hands. I prefer to hear what the public likes. And by "public" i mean people that actually compare products fairly.

On another note. I was just thinking. Why isn't there anyway to get any of the Switch's info. Its not configurable in anyway at all. I'm just saying, i wish i could do that "dd-wrt" to the switch and save all my money.
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November 25, 2011 12:32:48 AM

So let me simplify my previous question.

1. Will the server be able to maintain its own IP and have no problems when allowing connections to its Game Servers, FTPs, And/or Media Server?
Will i notice a difference or difficulty when adding the hub?
For Example:
Modem - Switch - Hub - Server
- - - - - - (switch) - Router - Home Network.

2. Is that the best place to put the hub. Because i want the server to have its own IP for several reasons.


EDIT:: Also note that having more than one connection with the hub decreases bandwidth for every new connection.
Both the Server and the Home Network are in high use so it is imperative that they both have access to the internet at all times.
(In this setup the hub would be merely a wire extension & WoL device.)
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November 25, 2011 7:50:47 AM

Best answer selected by TrinaryAtom.
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