DMVPN Phase 1 RIP Routing

(Rene Molenaar) #1

This topic is to discuss the following lesson:

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(madimba t) #2

Hallo Rene how did u config the tunnel?because it got the ip address of 172.16.123.in your configuration u only did HUB and the 2 SPOKES

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(Rene Molenaar) #3

Here’s the basic DMVPN phase 1 configuration that I used for this:

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(Safwan H) #4

Hi Rene,

Would you kindly help explain, where is the router interface IP network in RIP and how does it fit in the dynamic routing protocol as we only advertised the lO0’s as well as the tunnel IP’s

Thanks you,

Safwan

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(Rene Molenaar) #5

Hi Safwan,

What exactly do you mean with “router interface IP network” ?

By advertising the loopback interfaces and enabling RIP on the tunnel interfaces, we have everything we need for the routers to learn each others loopback networks.

Rene

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(Safwan H) #6

Hi Rene,

I meant network 192.168.123.x

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(Rene Molenaar) #7

The routers are directly connected on the 192.168.123.0/24 subnet. The tunnel interfaces are sourced from this subnet.

That’s all we need for DMVPN, connectivity between the NBMA addresses so that we can establish the tunnels.

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(Mahamane B) #8

Hello Jeremy.
What version of ios images did you use? I can find the command SHOW DMVPN on the router i’m using
Thanks.

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(DIONISIS) #9

Hi Rene,

i think there is mismatch between the DMVPN PHASE 1 RIP to the results of show ip route rip command ON THE spokes routers and other DMVPN PHASE 1 PROTOCOL LETS SAY EIGRP and show ip route eigrp (look at the next hop address)

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(Andrew P) #10

@Manhamane most labs are built using VIRL. Currently, the IOS version is 15.6.2.T

If you happen to be a GNS3 user, my favorite DMVPN image (which has everything you need) is c7200-adventerprisek9-mz.152-4.M6

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(Rene Molenaar) #11

@Dionisis Which output do you refer to?

Both RIP and EIGRP use the same next hop IP address in DMVPN phase 1?

Spoke1#show ip route rip 

      1.0.0.0/32 is subnetted, 1 subnets
R        1.1.1.1 [120/1] via 172.16.123.1, 00:00:17, Tunnel0
Spoke1#show ip route eigrp 

      1.0.0.0/32 is subnetted, 1 subnets
D        1.1.1.1 [90/27008000] via 172.16.123.1, 00:01:27, Tunnel0

Rene

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(DIONISIS) #12
Spoke2#show ip route rip 

      1.0.0.0/32 is subnetted, 1 subnets
R        1.1.1.1 [120/1] via 172.16.123.1, 00:00:01, Tunnel0
      2.0.0.0/32 is subnetted, 1 subnets
R        2.2.2.2 [120/2] via 172.16.123.2, 00:00:01, Tunnel0
Spoke2#show ip route eigrp | include 2.2.2.2
D        2.2.2.2 [90/28288000] via 172.16.123.1, 00:00:41, Tunnel0

but i think the sentence below explains what it happens
EIGRP changes the next hop IP address when it advertises networks.

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(Rene Molenaar) #13

Hi Dionisis,

That’s right, EIGRP changes it.

Rene

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(Noorudheen T) #14

Hi

please check the attached clip, here ‘no ip split-horison’ or jest ‘ip split-horison’.?

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(Rene Molenaar) #15

Hi Noorudheen,

I don’t see an attachment but the command is no ip split-horizon.

Rene

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(Mohammad Hasanuz Zaman) #16

Hi Rene,
So we call DMVPN is Dynamic mGRE alternatively , rignt ??

One more confusion regarding the output …

Spoke1#show ip route rip 

      1.0.0.0/32 is subnetted, 1 subnets
R        1.1.1.1 [120/1] via 172.16.123.1, 00:00:10, Tunnel0
      3.0.0.0/32 is subnetted, 1 subnets
R        3.3.3.3 [120/2] via 172.16.123.3, 00:00:10, Tunnel0

when Spoke1 want to reach Spoke2(3.3.3.3) , what will be next hop in DMVPN Phase 1 ?? . Its showing 172.16.123.3 but all traffic will go through HUB, right ?Thanks

br//
zaman

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(Rene Molenaar) #17

Hi Zaman,

mGRE (multipoint GRE) is one piece of the DMVPN puzzle. You also need NHRP.

In DMVPN phase 1, all traffic will go through the hub yes, there is no direct spoke-to-spoke communication.

Rene

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(MAODO T) #18

Hi,

In one of last capture images, the lesson says : “Above you can see the NBMA addresses”. That is said about loopback adresses 2.2.2.2 and 3.3.3.3 that are attached to Spoke-1 and Spoke-2 routers.

In the context of NHRP, could we say that NBMA does mean the same thing as the whole underlay network (including all “public” networks learned by the Spoke) ?

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(Lazaros Agapides) #19

Hello Maodo

The NBMA in this particular example refers to the nature of the actual physical network, and the addressing of the physical interfaces connected to the medium. That is, the 192.168.123.X subnet. So if this is what you mean by the whole underlay network, then yes you are correct.

I hope this has been helpful!

Laz

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(MAODO T) #20

I found the definition below of NMBA :

Multi-access means we have to select a DR and BDR.
Non-broadcast means that OSPF expects us to configure neighbors ourselves.

In the article :

According to that ; it seems that NBMA is that “kind-of Frame-Relay network” DMVPN builds on the underlay Network.

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