Remote users on alternate ISP's

[Avi Makritsu]

We use a static IP at our office for remote users to run an ERP application. Our current ISP has recently been facing downtime issues and this has become a big problem for us. So now we are in the process of getting a backup ISP so that we can be connected to the internet during these downtime.

Now my concern is that since the remote users connect to ERP using the old static IP, how can I configure the settings on the new modem router so that the ERP users remain connected without any problem. Some guy suggested me purchase router of the exact same old model and configure the exact same settings so that during downtime all we have to do is to switch the lan cable (from the old to the new router) and the remote users can still connect to our office. I am not sure if this will work. Please guide. Thank you

 

[bill001g]

What you want to do can only be done by huge enterprise size customers. You would have to run a actual routing protocol like BGP between you and the ISPs. When you have multiple ISP you must have your own AS number as well as a block of IP addresses that is assigned to you by one of the large organizations that own all the ip address. Even a very large company has issue getting this type of stuff approved.

Your problem is a variation of the above issue. The IP you are using is actually assigned to a particular ISP. The routing in the internet know to send all ip addresses in that range to that ISP. To make this work the ISP would have to somehow get a agreement to advertise its ip addresses in another ISP. Even if it could be done the minimum block of ips is 256, so it would move a bunch of other customers who may not be affected.

You only hope is to use something like one of the dynamic DNS servers. This would let you associate a name to your IP address. You could keep the name the same but change the ip address being used. This is not always simple especially if the application you use does not use DNS type of names and uses IP addresses. It also will be hard to change if the server actually has the ip assigned to it. And even if you get that to work it takes some time for the dns data to be pushed so you will have short periods of time where the wrong address is still in the dns servers.

 

[Avi Makritsu]

thank you for your patience and detailed explaination. Looks like Im up creek without pedal

 

[jsmithepa]

You cannot be possible suggesting the client application is hardcoded with a static IP? Is this one of those custom App somebody made and since long gone?

You are not the first person who needs redundancy I assure you, but maybe the "pieces around it" may need to be updated in a certain way to allow.