Maximum number of Hubs in DMVPN domain

[mabufardeh]

Hi All,

I have a large scale network where there are four Data Centers and about 90 branches.

these 90 branches needs to reach all 4 DC's, we think about DMVPN (Phase 3)  and to have 4 hubs in this scenario.

 the HUBs routers are ASR1004 and spokes' routers are ASR1002. already there are 4 domains of DMVPN phase-1 connecting the spokes to the hubs.

my question is can we have 4 active hubs at a time? so that each spoke has one tunnel to reach 4 hubs and routing to all subnets behind each hub..

all Cisco documents talks about maximum number of spokes you can have.

if there is a link or video from Cisco describing the answer, please share it here.

Thanks

[Rob Ingram]

I have personally not seen any documentation to say that a spoke cannot connect to 4 hubs at the same time.I do not see any reason why it's not possible.

This will of course mean each spoke must maintain 4 concurrent ipsec tunnels, this may have an impact on the routers resources if runnning low spec routers.

If you were concerned about running 4 concurrent tunnels you could have 2 active tunnels with 2 tunnels as backup - you'd define all 4 hubs with a priority and then use the command "ip nhrp nhs cluster 1 max-connections 2". Then only 2 concurrent tunnels will be active, in the event of failure the tunnel with priority 3 will become active and so on. I am assuming the DCs have connectivity to the other DCs, so the spoke sites can route through one DC to reach the others.