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AlexR1
AlexR1
New Member
January 6, 2022
Question

GRE tunnel via existing IPSEC tunnel

  • January 6, 2022
  • 1 reply
  • 3784 views

Hello,

We have an existing VPN site to site in hub n spoke with IPSEC.

In remote sites (spokes) , we have Aruba Access points that have to mount a GRE tunnel to an Aruba Wireless Controller in central site (hub).

 

I would like to know if it is possible, because Wireless controller send data to Access Point but access point is not responding.

 

Have i to change MTU for this IPSEC tunnel?

FortiOS 6.2

 

Thanks for help.

Regards.

1 reply

Toshi_Esumi
SuperUser
Toshi_Esumi
SuperUser
January 6, 2022

If Aruba controller and APs are the ones that encapsulate IP packets in GRE, they are the ones to adjust MTU (-8) before the encapsulation. Not FortiGates.

 

But if much shorter packets, like small ping packets, don't go through, the MTU is not the problem.

 

Toshi

AlexR1
AlexR1Author
New Member
January 7, 2022

Yes, it is controller which encapsulate. ping are OK between AP and Controller.

I will try to ajust MTU.

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