multiple DMVPN tunnles on one router

[Mike Buyarski]

is it possible to have 2 DMVPN tunnels on one router and have the tunnel IP subnet on both tunnels be in the same range(different IP's of course). The reasoning for this Q? is we have routers with 2 internet connections, primary(cable,t1,dsl,etc) and a backup cellular data card. One DMVPN tunnel would point to the gig interface and the other DMVPN tunnel would point to the cellular interface. the issue I am running into is the router does not let me add the ip address of the second tunnel because that range already exists. now I know I can add the "ip unnumbered interface (interface)" to get the ip to be in the same subnet. so

is this possible?

will it work if the primary link, and tunnel goes down and the backup takes over? or am I going to have issues since the tunnel with the ip unnumbered command will point to is down?

or will I have to have 2 different tunnels at the hub router? will the DMVPN work if there is 2 DMVPN tunnels pointing to the same interface at the hub router?

[syed kazim abbas]

plz see this may be help full

https://supportforums.cisco.com/discussion/11914456/dual-cloud-dmvpn-source-address-problem

http://www.dslreports.com/forum/r24132104-Config-DMVPN-reundandt-WAN-SOLVED-config-inside

[Mike Buyarski]

neither of those look like what i have as my question, the main difference is the my Hub only has 1 connection to the internet. While the spoke has 2 connections(primary and backup). is there a way we can have the tunnel source as both interfaces? the main problem i cant have 2 different DMVPN tunnels on the Hub source the same interface.

[David_Che]

Hi Mbuyarski,

MGRE + GRE protection = DMVPN.

why MGRE not multiple GRE on HUB?  

Its purpose is to simple and shorten GRE configuration on HUB.

So there is only one tunnel on HUB, of which tunnel mode is p-2-mp(point-to-multi-point).

There can be many tunnel on spoke, of which tunnel mode is p-2-p (point-to-point).

what you mean is to switch-over from the primary link to the secondary link in case primary link failure. You can configure two individual GRE tunnels to the HUB. whatever the GRE tunnel number on spoke(maximum 4K), there is only one P-2-MP mode GRE tunnel.

After the two tunnel setup, you can exchange spoke and hub LAN routes on those 2 tunnels, the data forwarding will automatically switch-over to the backup link when the primary link get failed.

Please let me know if you have any question.

Regards,

David

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[sachinga.hcl]

Hi Mbuyarski,

Could you please share your topology and router configuration so that we can see what exactly is configured as it will give us some insight on your setup.

Best regards

Sachin

[Mike Buyarski]

details

A, internet connection at the hub(dedicated and reliable)

B, internet connections at spoke(Cellular connection as backup)(primary not dedicated, reliable but less than a dedicated connection)

1. can i create 2 DMVPN tunnles on the hub that uses the same internet connection/interface(i know i can create more then one tunnel but i never used it on the same interface)?
2. i know i can create 2 tunnels on the spoke