GRE tunnel config

[kunal-united]

configuring GRE tunnel between R1 & R2 over the internet. R1----Internet-----R2. Works fine.

Now we need to have GRE tunnel between R1 & R3. R1----Internet-----R2-------R3.

So what is required to be configured/removed from R2 inorder to have the GRE tunnel between R1&R3.

R2- is now managed by me.

Thanks

[jyoung]

Traffic needs to be routable between R2 and R3 and gre needs to be allowed in r2 from R1 to R3 and reverse. Are you encrypting the tunnel?

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[Richard Burts]

I am not clear in the original post whether the intent is a change to move the GRE tunnel that was R1 to R2 and make it R1 to R3. Or whether this is to configure an additional GRE tunnel that will be R1 to R3 in addition to the existing tunnel R1 to R2. Perhaps you can clarify?

If the intent is to move the tunnel then the existing configuration of the tunnel on R2 must be removed, a similar configuration must be added to R3, and changes need to be made on R1 to change the tunnel destination. And you must be sure that there is IP connectivity between the addresses on R1 and R3 that will be used as source and destination addresses for the tunnel.

If the intent is add a new tunnel in addition to the existing tunnel then you do not need to remove anything from R2. You need to configure an additional tunnel on R1 and you need to configure the new tunnel on R3. You need to be sure that there is IP connectivity between the addresses on R1 and R3 that will be used as source and destination addresses for the tunnel.

HTH

Rick

[Marius Gunnerud]

R1 tunnel interface destination IP needs to be changed to R3s reachable IP. then R3s tunnel interface needs to be configured with tunnel source ip and destination IP.  Depending on if you are using encryption you would need to configure that on R3 also, as well as amend R1's encryption configuration to allow traffic to R3 and vice versa.