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One LAN with two Internet connections?
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Mar 6, 2013, 11:06 AM
 
Okay, I’ll preface this by saying I know this is really weird, but it’s the situation I’m in, so let‘s see if anyone has any great ideas.

Yesterday morning, I finally made the switch from DSL to cable. My speeds immediately quintupled and I was thrilled. Unfortunately, after a few hours it became apparent that we weren’t able to send nor receive emails. After two more hours on the phone with Comcast, a senior advisor informed me that their residential service does not support internal email servers. He’ll be calling back within 48 hours to let me know what they can do, but I’m expecting the options will be cost-prohibitive. In the meantime, I’ve switched back to the DSL connection, which is obviously slower but actually works.

Early this morning, it occurred to me that it would be considerably less expensive to maintain two Internet connections than to upgrade to Comcast Business Class. I could use the DSL modem for the server and the cable modem for everything else. Unfortunately, that would put the server on a different network than the other machines, which is obviously a problem.

So, therein lies the question: is there a way to hook up the server to a different Internet connection than the rest of the network, while still retaining the singularity of the network? I don’t want to give up my gigabit intranet connection just so I can have faster internet. If it helps, I have two gigabit AirPort Extremes.

Thanks so much!
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Mar 6, 2013, 01:57 PM
 
Because of the number of spam bot net zombies comcast blocks the outbound ports.

The server could be on both the local network and the dsl connection. Then you can configure the routing tables to send all non lan email traffic out over the dsl connection. How depends on the server OS. I'm assuming you don't have a commercial grade switch/router.
     
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Mar 6, 2013, 02:20 PM
 
Sure, there's a couple ways to do this.

1) Upgrade to a router that supports multiple active WAN connections. I think the low end Cisco ISR can do this, but the PIX can't.

2) Install a second NIC in the mail server. Connect the DSL modem to it directly on one interface, and connect to your Airport Extreme that serves the rest of your network on the other. Use routing or firewall shenanigans to route the email traffic on the DSL and the local and other traffic on the local network/cable modem.
     
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Mar 6, 2013, 03:26 PM
 
Originally Posted by BLAZE_MkIV View Post
The server could be on both the local network and the dsl connection. Then you can configure the routing tables to send all non lan email traffic out over the dsl connection. How depends on the server OS. I'm assuming you don't have a commercial grade switch/router.
Hey, Blaze. Thanks. No, I don’t have a commercial-grade switch/router, just an AirPort Extreme (GigE/802.11n). The server software is Mac OS X v.10.7.5 Server, although I also have 10.8 Server, if I need it. (The last time I tried to upgrade, it didn’t work too well. Long story.)

Any guidance on how to configure the routing tables? That sounds great!
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Mar 6, 2013, 03:28 PM
 
Originally Posted by mduell View Post
Sure, there's a couple ways to do this.

1) Upgrade to a router that supports multiple active WAN connections. I think the low end Cisco ISR can do this, but the PIX can't.

2) Install a second NIC in the mail server. Connect the DSL modem to it directly on one interface, and connect to your Airport Extreme that serves the rest of your network on the other. Use routing or firewall shenanigans to route the email traffic on the DSL and the local and other traffic on the local network/cable modem.
Thanks, mduell. The mail server is a Mac mini Server (we’re a small business), so a second NIC is out. Wish it weren’t; that would be nice.
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Mar 6, 2013, 04:52 PM
 
Originally Posted by bojangles View Post
Hey, Blaze. Thanks. No, I don’t have a commercial-grade switch/router, just an AirPort Extreme (GigE/802.11n). The server software is Mac OS X v.10.7.5 Server, although I also have 10.8 Server, if I need it. (The last time I tried to upgrade, it didn’t work too well. Long story.)

Any guidance on how to configure the routing tables? That sounds great!
Originally Posted by bojangles View Post
Thanks, mduell. The mail server is a Mac mini Server (we’re a small business), so a second NIC is out. Wish it weren’t; that would be nice.
Sorry you either need a real commercial grade router or two ethernet controllers. Or you know, a business class internet service plan.
     
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Mar 6, 2013, 07:15 PM
 
Originally Posted by bojangles View Post
Thanks, mduell. The mail server is a Mac mini Server (we’re a small business), so a second NIC is out. Wish it weren’t; that would be nice.
You could do a USB NIC for the second interface.
     
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Mar 7, 2013, 03:39 AM
 
Originally Posted by mduell View Post
You could do a USB NIC for the second interface.
Oooh… nice idea. Goodness knows we don’t need gigabit for a connection to a 5Mb DSL line. So in so doing, do you have any suggestions on how to go about the “routing shenanigans” (as you so aptly put it)?

Thanks again!
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Mar 7, 2013, 06:07 AM
 
You can add a manual route using the terminal command

route add destination gateway

run as root, where destination is the server or network you would like to reach and the gateway is the "next hop" you would like the connection to go through. If your mail server is called 12.34.56.78, the general Airport Express to the cable is 10.0.0.1 and the dedicated Airport Express on the DSL is numbered 192.168.1.1, you would put the connection to the 10.0.0.1 as the top priority link and then add a static route with

sudo route add -static 12.34.56.78 192.168.1.1

This would have to be done at every boot, so you would do best to make it as a startup item.

All this said, I would probably investigate VPN services before embarking on this idea.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
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Mar 7, 2013, 12:57 PM
 
If the mailserver is the only thing on his DSL, he doesn't need to burn an airport on it. Just plug the DSL modem into the Mac mini's USB NIC.
     
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Mar 7, 2013, 02:53 PM
 
mduell, you officially rock. I picked up a USB NIC from Best Buy, plugged the DSL modem into that, and made USB Ethernet the top service in System Preferences > Network. I then ran a line from the onboard NIC to the APE and made Ethernet the second service. The server is using the DSL connection, the rest of the network is using the cable connection, and the server and clients can all see each other just fine, as if nothing were strange at all.

Thanks a million!
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Mar 7, 2013, 04:00 PM
 
USB to ethernet for older Mac Minis, Thunderbolt to gigabit ethernet if you have a newer one. Both are cheap and plug & play.

Use the on board gigabit to share files etc with the rest of the network but set the service order to put the DSL connection above it in order to send and receive emails. Easy.
I have plenty of more important things to do, if only I could bring myself to do them....
     
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Mar 7, 2013, 04:17 PM
 
since the DSL is topmost, would any browsing in safari or internet activity in any application go through the DSL and not the cable connection?
     
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Mar 7, 2013, 06:32 PM
 
Originally Posted by abbaZaba View Post
since the DSL is topmost, would any browsing in safari or internet activity in any application go through the DSL and not the cable connection?
That is correct. This doesn’t cause a problem for us, though; the server only rarely gets used in that way.
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Mar 8, 2013, 08:22 AM
 
I took the liberty of assuming that.
I have plenty of more important things to do, if only I could bring myself to do them....
     
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Mar 8, 2013, 03:50 PM
 
was just wondering. gotta love simple solutions.
     
   
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