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My first GRE Tunnel, HELP

I'm attempting to build my first GRE tunnel using 2 celular routers with static IP addresses provided by Verison.


Right now I have the 2 routers connected to two different laptops, although I eventually want one to be connected to a PLC.


I can succesfully ping the two routers from either laptop using the static IPs given to me by Verison. However I can't ping either laptop from the other.


I'm doing my pinging using command prompt using the commands "ping",  "ping", "ping", "ping". All of these will give errors when used to try and ping the remote router or laptop.


Here's my current configurations.


Laptop #1

Local IP

Router #1

Local IP 166.255.a.b

Remote IP 166.255.c.d

Tunnel IP

Tunnel Subnet/Mask

Remote User Subnet & Mask


Laptop #2

Local IP

Router #2

Local IP 166.255.c.d

Remote IP 166.255.a.b

Tuneel IP

Tunnel Subnet/Mask

Remote User Subnet & Mask



Can anyone tell me what I've done wrong either in my setup or in my attempts to ping using command prompt?


Everyone's tags (3)
Hall of Fame Master

I can not tell from the

I can not tell from the information provided what the issue is. Please provide detail of how the routers are configured.


I am a little confused at what you mean when you give us

Remote User Subnet & Mask


Remote User Subnet & Mask

These would appear to be in the same subnet. But they are given on different routers. Please clarify how subnet 192.168.50 can be on both routers.






Beginner and and are the LAN IP address that the individual routers are assigned. Since I've never done this before and am only trying to follow a simple guide left for me by a previous employee, I was assuming I should use these IP addresses followed by a /24 for the remote user subnet & mask field.


Honestly I don't even know what a subnet or mask is.


Hall of Fame Master

Thanks for the clarification.

Thanks for the clarification. When you say that these are the LAN addresses does this mean that they are addresses in a LAN to which both routers are connected? That could make sense but then it is misleading to refer to them as Remote User Subnet. Or is it that each is a LAN connected behind the router to which users connect. That could make sense but then there is an issue because they are separate LANs but the IP addressing indicates that they are in the same subnet.


Configuring a GRE tunnel is pretty easy (after you have configured them a few times) and I believe that we can help solve your issues if you provide us sufficient information about what you are doing. As a start would you post the configuration that you have so far for both of the routers? It might also be helpful if you could post a simple diagram showing the routers, how they are connected, and the LAN through which each PC connects to its router.






I ended up solving my problem

I ended up solving my problem.


I once someone at work explained to me what a subnet was and how a GRE truly works I found my problem.


I was trying to connect two networks that had the same subnet. I didn't realize that I couldn't use the same first 3 numbers, ie "192.168.1" on both networks. I changed one of the network's subnet and it worked.


Thanks for trying Richard.

Hall of Fame Master

I am glad to know that you

I am glad to know that you solved your own problem. That is frequently when we learn the best lessons. The issue of trying to connect two networks that had the same subnet is what I was trying to identify in my response. I am glad that someone at work was successful in explaining it to you. Thanks for posting back to the forum to let us know that you have worked it out.





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