I need some serious help with a complex routing setup I am doing.
Lets I have a /24 IPv4 .I am announcing the same /24 at two different locations. One is a ISP exchange center where all the ISPs peer each other locally.To make it simple just understand that this network does not has internet connectivity but yes the /24 is being publicly announced.So except the users on ISPs peering each other cant connect through this pool.Lets say this is NETWORK A.Lets call the server on NETWORK A be ALPHA.
Now I am announcing this same /24 at server outside the above network.The routes are announced on internet so every user on internet is connecting to me through this server.Lets say this is NETWORK B and Server on this network is BITA.Now I am routing all this traffic through a GRE Tunnel to the APHA Server located in my above network.Keep in mind, as I stated the users on the NETWORK A would be connecting directly to my APLHA Server in NETWORK A as due to short routes defined. My basic aim is to route all the traffic to the server in NETWORK A.Now this happens :-
A user connected on NETWORK A connects me through NETWORK A.He has no issues with connectivity. Now we have NETWORK B on other side.Let me tell you NETWORK B is routing traffic to server in NETWORK A through a GRE Tunnel.Now traffic is being forwarded to a IP which is Internet Enabled in the server.So in the server there are two lines NETWORK A connection line and Internet Line.Its receiving traffic of NETWORK B through GRE Tunnel through this Internet Line.So we have this scenario here :-
NETWORK A Users - NETWORK A - APLHA SERVER NETWORK B Users - Server Routing Traffic Through GRE Tunnel - Internet Line - APLHA SERVER
Now there is no problem with NETWORK A Users.I need to learn that once i receive the routed traffic coming from GRE how to connect it with traffic of NETWORK A.Like combining two networks through a single gateway and then sending it to the server or what should I do ? Also i need that the TCP or UDP Packet coming from NETWORK B should go back through GRE Tunnel back to NETWORK B Network and then return the packets from there so I need this thing to be done exactly.
Lets say I have a /24 - 103.XX.XX.XX
/24 103.XX.XX.XX is being announced at NETWORK A
USER SENDS TCP/UDP Packet to 103.XX.XX.12:27015 - NETWORK A - APLHA Server - Packet back to NETWORK A - USER
/24 103.XX.XX.XX is being announced at NETWORK B ( Same /24 of NETWORK A)
USER SENDS TCP/UDP Packet to 103.XX.XX.12:27015 - NETWORK B - BITA SERVER - GRE TUNNEL - Internet Line - APLHA SERVER - TCP/UDP PACKET BACK to Internet Line - GRE TUNNEL - BITA SERVER - NETWORK B - USER
Please help me with this.This looks really complex but it reading it once or twice will make it more clear.Also i need help step by step as I am not very well versed with Networking.Also I need to do this complex setup and cant avoid it.If i need to be more clear let me know.Let me know if i need to setup a gateway or router in between or whatever.I have added a very basic small picture of what I want and i am not a expert and dont know perfect symbols so just a basic paint picture.Thanks for helping :)
I cannot post images so here is the link - http://s2.postimg.org/abr4idx6x/Solution.png
Let me know if its not allowed here.