DMVPN issue

[ittechk4u1]

Hello Experts,

i am using this design from DMVPN.

1. Can i use two hub also both working as soke at the same time ?

2. I am using HUB as spoke because both are located on diff physical location.

so will it work or not ?

Thanks in advance

[Rich Uline]

ittech,

Dual hub DMVPN is certainly a valid configuration. See page 28 here.

[Francesco Molino]

Hi

Before answering your question, do you mind telling us:
- why are you using 2 clouds ? Is there a specific reason?
- You can have a design with 2 Hubs and a single cloud. Those 2 hubs can talk each other but in terms of spoke, it would be 1 cloud with a hub cluster. Is that something you're interested in?

Now, for your question, you can have a Hub being a spoke of 1 cloud DMVPN and at the same time building up a new cloud where this device is gonna be the Hub.

[ittechk4u1]

Thanks for reply..

- there is no specific reason of using two clouds. I can laos use one!!!

- I dont understand this "you can have a design with 2 Hubs and a single cloud. Those 2 hubs can talk each other but in terms of spoke, it would be 1 cloud with a hub cluster. Is that something you're interested in?
"

As my both HUB is in diff location ...How can i achive redundency?

Info: I am using diff provider for oth clouds...

- Whats wrong with my config (If want to have HUB and spoke at same time )

Thanks

[Francesco Molino]

Hi

Your config seems to be ok.

On spoke side, instead of having 2 cloud to manage, you can just have 1 tunnel pointing to 2 hubs. 1 connection to 1 hub (primary) will be active and the link to the 2nd hub will be in standby and bring UP when 1st hub is down. You can also have the 2 links up at the same time.

In terms of config on spoke devices, it will just be a matter of adding the following commands:

 ip nhrp nhs HUB1_IP priority 1 cluster 1

 ip nhrp nhs HUB2_IP priority 2 cluster 1

 ip nhrp nhs cluster 1 max-connections 1

 ip nhrp nhs fallback 5

Again your design is ok but you're adding a little bit of complexity by managing routing preference for both clouds.

Hope my explanation is clear enough

[ittechk4u1]

Thanks and i am agree with you ..

could you please modify my config(attached on main post) !!!

I took the above design becuase in case HUB1 is down then atleast i can reach to it(HUB1) via HUB2.

I need to access all (Including both HUB and all spokes) in case of any issue with any tunnel.

Thanks

[Francesco Molino · Accepted solution]

Hi

Here is the sample config. Please review it before applying (validate address and tunnel). I've done it through my iphone, but I think I didn't do any copy/paste or delete issues).

I didn't touch your routing (I just removed static routes from the text file to have a better visibility but you need keep them). When all tunnels are UP, you can remove the tunnels for cloud 2.

Thanks

[ittechk4u1]

Thanks for the help. I will try it.

But I have one more question:

If my Hub1 ISP (Gig0/0) is down, how I will reach to HUB1 location/plant from any other spoke or HUB2 ?

I want failover for both location(.HUB1 an HUB2), as both location are really important for me and both needs to be online in any case.

Thanks again.

[Francesco Molino]

Hi

Now we are out of DMVPN cloud. If your Hub1 ISP link goes down, you have no access anymore to this device.
You have 2 choices:
- Add a 2nd ISP link on both side to make sure this situation isn't gonna happen.
- I don't have the visibility on your upstream. Do you have a mpls or direct fiber or another link connecting those 2 DCs from the internal network (g0/1 for example?). If yes, you'll manage it on the routing prospective to make sure someone arriving at Hub2 can reach Hub1.

My real question is:
- You have 2 Hubs in your DMVPN cloud with 1 ISP link at each site. Why do you want to have always connectivity for both?
I mean it's a stupid question, but answering that one we can maybe recommend a design... However, to do so, we need to have an overview of what's going on on the upper layer.

[ittechk4u1]

Hi,

Thanks for quick reply.

Basic info:

1. Both HUB have two ISPs connected.(Ex: ISP1 and ISP2)

2. We have direct internet connectioin (Fiber leased line).....on on both HUBs

3. These are not datacenters..... I have divided by regions..like ASIA(6 small plants), EU(6 plants) and Americas(7 plants)

 - All plants are connected to DC via GRE P2P tunnels-  I will not touch this

 - All I want is to have DMVPN implemented in regional basis so that each regional plant can communicate to each directly.

4. I will have 2 HUBs for each region.

5. Above config was for ASIA region and both HUBs are 1200 km apart.

My design (in main post) was based on ISP line....

DMVPN cloud 1 was for ISP1(HUB1) and ISP1(HUB2).

DMVPN cloud 2 was for ISP2(HUB1) and ISP2 (HUB2).

My real question is:
- You have 2 Hubs in your DMVPN cloud with 1 ISP link at each site. Why do you want to have always connectivity for both? 
I mean it's a stupid question, but answering that one we can maybe recommend a design... However, to do so, we need to have an overview of what's going on on the upper layer.

Answer: I need HUB1 and HUB2 must be availabe in any case.....becuase Both locations are JIT(Just in time) , JIS (Just in sequence) and also Call manager is placed in HUB1 for all all regional location in ASIA.

Again ....

Every location have 2 ISPs (ISP1 and ISP2).......if you have better design then please ....

Thanks

[Francesco Molino · Accepted solution]

Hi

If you have on each hub 2 ISP links, then the chance to loose completely a hub is very low, except hardware failure. If your 2 ISP links go down then you'll also loose this hub but again chances are very low that should happen as your 2 links are from different ISP.

Now, in terms of DMVPN, with that design, you can create a new cloud that will be mounted over the 2 ISP link. It's the same design we discussed before but a new cloud for the new ISP link.

Is that clear?

[ittechk4u1]

Yes I got your point. But then again I will have two clouds for two diff ISPs

But it will be almost similer to my current design(In main post)!!!!!!!

I am using HUB1 (for ISP1) , HUB2 (for ISP2) and same for all spokes...

Spoke1  and HUB1 is using Tunnel 156 via ISP1

Spoke1  and HUB2 is using Tunnel 150 via ISP2

Thanks Again. You cleared my all doubts.

One more help: Could you please provide me the config for two dmvpn clouds as per your design(HUB1, dmvpn1 (ISP1) and Dmvpn2(ISP2)) because I am not good with cluster config!!!!

Thanks....

[Francesco Molino · Accepted solution]

Hi

You'll have 1 cloud with ISP1 including your 2 Hubs as cluster and 1 more cloud for ISP2 with again your 2 hubs as cluster.
You'll need to prioritize your 1 cloud routing process to make sure everyone is gonna take the same path.

Right now, I can't do the configs for you from my iPhone but later tomorrow or over the WE I will be able to drop you some config sample.
Is that ok?

[ittechk4u1]

Ok Please send me the conifg (When you have time!!)

Thanks for your great help. It is really appreciated.

Have a nice day!

[Francesco Molino · Accepted solution]

Hi

I used the subnet 172.25.157.0/24 for tunnel on this new cloud. The public IP are the same as before but you need to change them with ISP-B IP address.

The config is just the same as cloud 1 except for:

- public ip

- network-id 

- and delay on the interface to make sure your EIGRP process is gonna take cloud 1 as default path and goes to cloud 2 only when HUBs in cloud 1 are down.

Be careful before applying. You need to adapt it with your real informations.