eBGP over DMVPN

Unanswered Question
Sep 19th, 2009

Dear Experts !


I have a WAN network using DMVPN technology and OSPF as the Routing protocol. But Im having some issues like area-split , Summarization , policy routing / filtering.


Im thinking of changing the protocol to eBGP to simplify things. And extensively use BGP Summarization and Policy features.


Has anybody configured eBGP over DMVPN ?

Can you share your experience , any issues face and any advices.


Topology - http://img17.imageshack.us/img17/2035/bgpdmvpn.jpg

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Paolo Bevilacqua Sat, 09/19/2009 - 04:57

Should work, but if it's just an entrprise network w/ backup, consider good old RIP, easy to customize to the extreme.

lamav Sun, 09/20/2009 - 00:48

Hi:


It can work, but the interesting part of it is that the biggest selling point for DMVPN is that there is a zero-touch feature on the hub. That means you can dynamically add spokes without having to perform any configurations on the hub. Moreover, the spokes can have dynamic addressing of their public interface (like DSL). That means the hub doesnt have to be statically configured to talk to the spoke.


If you decide to go with eBGP, all that is lost. You will have to manually configure the BGP peering on the hub and if the spoke is dynamically assigned an IP address by an ISP, you will have to go to the hub and manually configure the peer address once again.


HTH


Victor

Paolo Bevilacqua Sun, 09/20/2009 - 02:31

Totally agree with Victor.


Why going the very complicated route when a much simpler one would work just as well.

Muhammad Zeesha... Sun, 09/20/2009 - 03:24

Thanks for the Replies.


If you can see in the topology every Branch has two connections to the Hub. These come from Different ISPs. There are also other Branches that directly connect to hub via P2P links.


The Primary Function using DMVPN in this topology is to reduce the amount of tunnels.


So im thinking of using 2 DMVPN Tunnels on every Branch. And one DMVPN tunnel per ISP on the HUB.


I think BGP can work very efficiently in this design because of the heterogeneous type of connectivity.


Also need to make sure Spoke Routers donot become transit in any case


Zeeshan

Paolo Bevilacqua Sun, 09/20/2009 - 03:30

I have a similar topology is more than one customer of mine.


In some case, redundancy is done with two DMVPN clouds, but more practical is to use a single one with two hubs in the same cloud.


eBGP was never needed, and spokes never become transit.

Muhammad Zeesha... Sun, 09/20/2009 - 03:33

How can i use a Single DMVPN Cloud when there are two different ISPs .. two different physical networks.


One more thing to mention. The Physical Connectivity is not Internet. Its Private ISP connectivity

Paolo Bevilacqua Sun, 09/20/2009 - 03:48

You simply configure the two hubs to be in the same cloud. There are examples in the white papers for this.


Internet or private network doesn't make a difference. Al tough, DMVPN on a private network is generally not necessary.

Muhammad Zeesha... Sun, 09/20/2009 - 19:51

Can you direct me to that white paper.


Im a little confused because the two Private ISP Wan Networks are seperate.

So how could I form a single DMVPN overlay cloud.



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