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Beginner

DMVPN using 4g with dynamic public IP address

Hello,

 

We have a medium sized DMVPN network that is working fine in Phase 3.

 

We have a new site that is using 4g as its primary connection. Every 12 hours the public ip address of this 4g connection changes causing the tunnel to drop.

 

By adding this command on the spoke the tunnel re-connects after about 5 minutes:

 

ip nhrp registration no-unique

 

This is not really ideal and wondering if anyone has an understanding of how this can be made better.

 

Manually executing clear ip nhrp also fixes the problem but again not ideal.

 

Using a Cisco 881 running 15.4 for this spoke.

 

Any ideas or suggests?

 

Adam

Everyone's tags (4)
3 REPLIES
VIP Advisor

Re: DMVPN using 4g with dynamic public IP address

Hello,

 

you might want to try and set the 'ip nhrp registration timeout' on the spoke tunnel to the lowest value possible...

 

Can you post the configuration of your 881 ?

Beginner

Re: DMVPN using 4g with dynamic public IP address

Hello,

 

Thanks for the suggestion. I just tried that and it did not seem to make any difference. Looks as tho connectivity drops for around 30 minutes. Whats odd is that it does not seem to be off for a consistent amount of time. The router loses internet access for about 20 seconds when the public IP changes. Worth highlighting the public IP address is assigned to a device in front of our router and we receive an NAT'd ip.

 

Tunnel config:

interface Tunnel1
ip address INTERNAL IP
no ip redirects
ip mtu 1400
ip flow monitor NTA input
ip flow monitor NTA output
ip nhrp authentication EXAMPLE
ip nhrp map multicast PUBLIC IP
ip nhrp map INTERNAL IP PUBLIC IP
ip nhrp network-id 1
ip nhrp holdtime 30
ip nhrp nhs HUB IP
ip nhrp registration no-unique
ip nhrp registration timeout 10
ip tcp adjust-mss 1360
tunnel source FastEthernet4
tunnel mode gre multipoint
tunnel key 100
tunnel protection ipsec profile EXAMPLE shared

 

Thanks

Adam

VIP Advisor

Re: DMVPN using 4g with dynamic public IP address

Hello,

 

I have a feeling the problem is related to the 4G. Can you post the full configuration of your router ?

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