Redundant internet connections

T1 will certainly do it, but that will cost you.  The first question I have is why do you need it?  If you have a single server handling mail, then the issues that take out your internet, will often take out your server too.  If it is something like you are just trying to balance the bandwidth a little better, like normal internet traffic in one pipe, and all email, active sync, etc, traffic in the other, then you will need a router that handles two or more WAN links.

As for ease, but kinda costly, I have found untangle to be pretty easy to use.  Web interface is clean, and it is fairly robust.  You do need a dedicated computer with multiple NICs to run it though, and the feature you are looking for is about $50 a month.

Other good choices are sonicwall's TZ 100 for small business.  IT can handle ISP redundancy as well as rules that will allow you to seperate your traffic.  It runs in the high $200's.

If you are looking for something to spool your mail while your server, power, internet connection is down, then something like MXLogic (now Mcafee, but I refuse to call it part of them) will do you better and far cheaper.

I have inbound traffic, so I need the public IP to be announced on both circuits.  My ISP keeps going down, so I'm looking for other options.  A T1 is enough bandwidth.  I just need redundancy.

Right.  I can use two MX records and point at two IP addresses.  Perfect.  Thanks!

I will use multiple MX records for my inbound email

The problem with redundancy is that any common point compromises that.  If all your T1s are on the same telephone pole when it gets wiped out by a car, you didn't have redundancy.  A major long distance carrier in the 1990s thought they had redundant fiber paths to/from the local switching center... but all of the fiber first crossed the river on the same railroad bridge.  When they had an accident on the bridge, all of their fiber was cut and they had major outage.

Actually getting redundant paths may turn out to be pretty expensive.  Phone and cable companies usually just connect you straight back to their central office or servers.

Without BGP, it is difficult to ask two unrelated ISP to route the same public IP you have. (in your term, bound to both circuit) In general, BGP offering require T1 or better service from your ISP.

The key here is either the public IP is not important for your applications (e.g. out going web traffic), or the application itself have mechanism to handle alternative public IP address (e.g. SMTP).

Ok, then I would recommend something like the sonicwall TZ series.  It comes with multiple ways to connect it and generally has one default WAN link, but four others you can program to be WAN links.  You can then get a DSL, cable, whatever with a static IP to get the redundancy.  T1 is only needed if you have specific purpose, but if you don't need the upload speed, and there are alternatives, then cable, dsl will be much cheaper for you.Just pick a different type than what you currently have.  If you have inbound traffic, such as your email server, then make another MX record for your other IP.

http://www.sonicwall.com/us/products/Failover_Failback.html for some reading on the sonicwall features.