Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Community Member

how to do dynamic ipsec hub-spoke gre using IOS tunnel protect

I like the simplicity of the Dynamic Multipoint GRE tunnels using NHRP that are shown in a couple of the sample configurations, but my network doesn't have a need for spokes to talk to each other. How can I keep the simplicity of config but not create NHRP mesh connections between spokes?

3 REPLIES
Cisco Employee

Re: how to do dynamic ipsec hub-spoke gre using IOS tunnel prote

Dynamic spoke-to-spoke tunnel creation is really just a feature of DMVPN, there's not really any way or need to turn it off. If no traffic flows from spoke to spoke, then the routers won't create tunnels to them. The tunnel from spoke-to-hub is always created automatically, but spoke-to-spoke tunnels are only ever created if needed, so if there's no traffic then don't worry about it.

Even with spoke-to-spoke communication though, you need to make some routing protocol tweaks to make sure traffic still doesn't flow via the hub. Check out the EIGRP/OSPF sections under this sample config:

http://www.cisco.com/warp/public/105/dmvpn.html

In short, just configure it up as shown, and don't worry about the spoke-to-spoke tunnels cause they won't be created if they're not needed. DMVPN makes configuration of the hub in particular much, much easier.

Community Member

Re: how to do dynamic ipsec hub-spoke gre using IOS tunnel prote

That's the thing, though. In our WAN there should be no spoke-to-spoke tunnels since all the resources are at the hub. Yet, with all the viruses and things that are running around, some host that decides to do a scan will cause a bunch of transient tunnels to be created. Are there some thresholds or restrictions that can be implemented to make dynamic tunnel creation more "difficult"?

Cisco Employee

Re: how to do dynamic ipsec hub-spoke gre using IOS tunnel prote

OK, forget my first post, not enough coffee that morning.

If you really don't want spoke-to-spoke comms, just don't configure "tunnel mode gre multipoint" on the spokes. This turns them into a point-to-point connection and with the explicit "tunnel destination x.x.x.x" command pointing to the hub, the spokes can ONLY send packets to the hub.

Take a thorough read of http://www.cisco.com/warp/public/105/dmvpn.html, it'll tell you everything you ever need to know about DMVPN.

227
Views
0
Helpful
3
Replies
CreatePlease to create content