Strange happening with 2 modems & 1 switch on network

tankman1989

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Ok, I originally had 2 isolated networks. One 12/2Mbps DSL with a Linksys and a 12/2Mbps Cable w/ netgear router and then a switch that feeds the rest of the network. The DSL connection is basically only for testing and redundancy.

So when the DSL guys came back the 3rd time they wanted everything unplugged and mangled the cords and I haven't had the 3 hours to tidy it back up.

Somehow, when they left, they plugged both the routers into the switch and showed me that I was getting access so they left. This was a speed call problem. Well the speed test was running on my cable modem, which is constant 12/2 or more like 15/2.5 to be exact. I thought they had done some magic.

So over the days I realized that my normal FTP downloads were dropping every 15 mins and I was getting 1/12 speed (DSL speeds). But this couldn't be, I was on the Cable machine through the switch! I was thinking "DAMN" now my cable company is all buggered up as well. When does this end!

So I decided to try to IM someone on uTorrent (impossible I know) but I got his IP and gave it a go. The site showed my IP as out of range of my cable company so I thought that was odd. I went to my router GUI page and it was my Linksys! WTF!? right! Not supposed to happen! Well I did some testing and all my traffic is being pushed through the DSL line which is why it has been SO slow since they were here. :mad::mad::mad::mad:

I pulled the cable out of the switch and let it hang like it should, waiting for the laptop for testing purposes.

Now everything is back to normal but that was 3 weeks of severe headaches as I couldn't figure out why my network, which was 100% perfect before, had gone to the dumps. Those Windstream repair guys who aren't techs but "phone guys".

I actually heard one of the techs say, while sitting right in front of me "you know I really wish, just one time on a call, that we could be the teacher instead of the learner everywhere we go". I didn't know how to process that. These guys were always on the phone with "b-tech" getting "advice" which usually didn't help much, but when I told them what to do, b/c I've been through this specific situation about 20-30 times, it actually worked, but they aren't allowed to listed to the clients for some reason - they are just allowed to waste as much time as they can of theirs.

So, how does a switch know which router to send traffic to if there are 2 connected? In my case, it was obviously the slower and it was the router which appeared later on the network. I would have thought that it would have established routes and the new router would have just been ignored as the routes were already in place..

Ideas?
 
Simple. Your routers each have a unique IP address. Lets call the DSL connection router A with an IP of 192.168.1.1 and the cable router B with an IP of 192.168.1.2. Whichever router IP you use as your gateway IP will determine your WAN connection. This will most likely be the one that is running DHCP. If your assigning statics on your machines then its up to you to assign the gateway IP of choice. If you use IP A as your gateway address, then your surfing on DSL.

If you want true redundancy, get a firewall with failover capability. You will set a primary WAN and a secondary WAN. When one goes down the other will work as a backup. In your current situation, you will need to change your gateway IP on your machine to whichever WAN connection is preferred, or live if one has failed.

Make sense?
 
So, how does a switch know which router to send traffic to if there are 2 connected?

Workstations will control that by specifying the gateway address. Refer back to your network training...remember what a gateway is. Not a router...but a gateway. Now most home grade and small biz routers happen to function as gateways by default.

Hopefully you have each routers of yours on different IP addresses, right? Same IP range? Like Stinksys is at 192.168.10.1 and the Nutgear is at 192.168.10.2 or .254. Both are not running DHCP right? Just 1? Or a server is?

Better design really would be to have 1x router that has multiple WAN ports.
 
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