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I have a network, and it has had serious trouble since before I started working on it. It continues to be problematic at best, and down right broken at worse. I'm pretty much at my wits end with it!

Here's the setup- We have internet traffic being sent in, then split between a router, a netgear prosafe FVG 318 (regular internet) and an edgewater SIP phone system. The netgear plugs into a 24 port POE switch which then serves the building.

Here's the problem- The network is insanely spotty. People are constantly loosing connection off the wireless, and I finally decided to assign everyone (including our SIP phones) static ip's, which seems to stabilize the connections some what. However, when attempting to use DHCP to connect, often users will not be able to authenticate and receive a valid IP address. This happens for both wired and wireless connections. The weird thing is that some times it works, and other times it does not, but it NEVER works for wired connections from the switch, and sometimes works for connections to the router. the DHCP is not allowed to assign ips in the ranges assigned for static ips. While monitoring the connection with ping -t, about every 20th result returns either unreachable or times out.

resetting the router/WAP seems to help these problems, but they come back quickly. At one time there were two DHCP servers running on the network, and I disabled the other server, and let the router serve the IPs.

Lastly, we just got in two WAP's to extend our wireless network to the far ends of the building, but I don't want to install them until I find out what is wrong with the rest of the network, or else I"ll just be making a bad situation worse.

So here are my two questions:

  1. What is causing the DHCP server to not serve IP addresses correctly?
  2. How should I set up the wireless? Does having it on the same subnet cause IP conflicts, and if so, should I create a second subnet?
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migrated from stackoverflow.com Jul 25 '12 at 22:06

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oh, one last thing, windows net bios is often screwed up, I usually can't see other computers in the work group –  David Brilliant Jul 25 '12 at 20:00
    
Is there anything in the DHCP server logs? E.g. if it does not receive the DHCP-req then it will never answer. (And thus the DHCP server itself might be fine). –  Hennes Jul 25 '12 at 22:23
    
You're going to want to do a packet capture on a DHCP handshake (ports 67/68). The capture will give a good indication of where the breakdown in communication is. As far as your network goes, it sounds far more complex than it needs to be. If you have an edgewater network device, why do you need the netgear? I used to do support for these devices on SIP networks and can give a pretty good solution if you're willing to remodel your network a bit. –  MaQleod Jul 26 '12 at 6:44
    
First off, the edgewater device should be the DHCP server. This will NAT and provide all your phones with their private IPs and should allow them to correctly authenticate with the SIP server as this is their gateway. If you have a routed block, the edgewater will let you set that up in conjunction with the private block and you can serve this to your computers. If you don't need a public block, you can just allow them to use the private block without any issues. –  MaQleod Jul 26 '12 at 6:47
    
Ensure that traffic shaping is setup correctly as well. It should be set to leave at least 10% of your total bandwidth free (this guarantees that your data will not overrun your voice). You should then plug the 24 port switch into the edgemarc (all your phones and computers can plug in here). If you really need to use the netgear, put it on this side of the edgewater and disable DHCP and NAT. –  MaQleod Jul 26 '12 at 6:49
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