Network Loops and/or other switch problems.

Hey all,

I have been looking at some problems with our network and am trying to figure out if the switches are my problem. The problem seems to be related to my 2 Netgear/Firewalls. These firewalls have an integrated 4 port switch, as do most commodity type firewalls and routers.

The network is broken into a private network with 3 DMZs. The DMZs are separated by the 2 Netgear firewalls and one Asus firewall (not the issue here). We have 2 Internet connections (SBC and Covad). The Web traffic comes in from the Covad connection and the outgoing traffic goes out the SBC connection.

Following is my current network (btw the device between the Netgear Firewalls is a switch):



What was happening before was that my users on the private network (10.0.0.0) would periodically lose connection to the SQL Server. If you looked at the NIC card on Sql Server the connection light would be off and the Server would say it was unavailable. The Network was slightly different at the time.

The difference was that NetGear1 went directly into Netgear2. The Sql Server was plugged directly into Netgear2. The lights on Netgear2 1 would also be off. If I restarted Netgear1 (assuming this was the problem), I assumed that the connection to the Sql Server would be restored since it was connect directly to Netgear1. This was not the case.

I had to restart Netgear2 to get it to work. As soon as I did this, the lights on Netgear1 came back on as did the Sql Server Nic card and everything was fine for awhile. So Netgear2 was controlling Netgear1 and because of that also the Sql Server.

I thought maybe this was a Spanning Tree problem as I don't know if these small Firewall/Switches have STP. As I look at it, I am not sure this is the problem as I don't see any redundant paths.

What I did to solve the problem was get another small switch and put it between the Netgear1, Netgear2 and Sql Server. This seems to have help the problem somewhat.

But periodically (not often), it happens again and I have to reboot the firewalls and switches. It doesn't happen enough for me to figure out which device is cause the problems.

I am still confused as to what could be causing the problem and was curious if anyone else might have an idea.

Also, I am looking at upgrading the network but not sure the best/"best cost" switches to replace my switches. I was looking at Cisco, Linksys (higher end switches), HP Pro Curves and Extreme Network switches. There doesn't seem to be much out there comparing the different switches and was looking for some others that have had some experiences with these (or other) switches. We are on a moderate budget. We want to get some better devices but not break the bank.

Sorry, I can't be much help in trying to figure out what's going on with your netgear firewalls, but I do have one question - why such a complex configuration for such a relatively small setup? Dual-homed servers, and multiple cascaded DMZ's using soho firewalls, etc. Just seems like there might be a more streamlined way to set it all up that also might eliminate your strange issue. Take advantage of that checkpoint!

Hope it might be because of the switching Loop only.

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Dove