DMVPN and NHRP

Answered Question
Jul 7th, 2009

Many Cisco DMVPN (Dynamic Multipoint VPN)documents refer to NHRP (Next Hop Resolution Protocol) as the routing protocol to be used with dynamic IP addresses on spoke routers.

If I am using static assigned IP addresses on the spoke WAN facing interfaces, do I need to configure NHRP?

When configuring DMVPN, is NHRP automatically configured or is this a seperate configuration I must manually setup?

Does anyone have a current link to a Cisco NHRP document?

Tks

Frank

I have this problem too.
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Correct Answer by Jerry Ye about 7 years 4 months ago

Hi Frank,

If you are doing DMVPN phase 3, you still need NHRP. The reason is you are not going to build static tunnels, and you still want spoke to spoke traffic to use your NMBA tunnel when there is traffic need to go from spoke to spoke. Where NHRP will be needed to help resolve spoke's physical interface IP address.

HTH,

jerry

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Joseph W. Doherty Tue, 07/07/2009 - 11:18

"If I am using static assigned IP addresses on the spoke WAN facing interfaces, do I need to configure NHRP?"

Believe the answer is yes, since NHRP is what informs the hub what the spoke's IP is.

"When configuring DMVPN, is NHRP automatically configured or is this a seperate configuration I must manually setup? "

Believe the answer for this is manual configuration, although it's only a couple of statements.

"Does anyone have a current link to a Cisco NHRP document? "

Don't have a good one to post, but if you have SDM, believe it can configure DMVPM for you.

Jerry Ye Tue, 07/07/2009 - 15:11

Hi Frank and Joseph,

When you configure DMVPN with NHRP, NHRP configuration need to enter seperately.

I am not sure what kind of NHRP document you are looking for, however, please see the following link for configuring DMVPN phase 1 with NHRP:

http://www.cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a008014bcd7.shtml

Here is the link to the NHRP configuration for IOS 12.4:

http://www.cisco.com/en/US/docs/ios/ipaddr/configuration/guide/iad_cfg_nhrp_ps6350_TSD_Products_Configuration_Guide_Chapter.html

HTH,

jerry

fsebera Wed, 07/08/2009 - 03:51

Thanks this detail, info provided will get me going in the right direction.

My research thus far indicates NHRP is required on NBMA clouds which we currently have - running DMVPN phase 2.

We are moving torwards DMVPN phase 3 across a layer-3 MPLS cloud (with static wan interfaces) and am not sure if NHRP will still be required in this new setup. I am not the design engineer on this project so I have much research to complete.

Thanks again for the help

Frank

Correct Answer
Jerry Ye Wed, 07/08/2009 - 05:06

Hi Frank,

If you are doing DMVPN phase 3, you still need NHRP. The reason is you are not going to build static tunnels, and you still want spoke to spoke traffic to use your NMBA tunnel when there is traffic need to go from spoke to spoke. Where NHRP will be needed to help resolve spoke's physical interface IP address.

HTH,

jerry

fsebera Wed, 07/08/2009 - 07:42

Thank you Sir!!

Nothing like concrete information!!!

Excellent

Frank

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