Multipoint GRE

[jpl861]

Hi,

I'm trying to figure out if it is possible to do mGRE without doing DMVPN. With DMVPN, the spoke-to-spoke establishment would just be established right after spoke-to-hub is up. But I am trying to see if it is possible to configure the entire mGRE cloud like a multipoint frame-relay interface where each site can talk to each other directly. I have done some simulation and there are few things I have but not sure if it will really work in a production environment. I have created multiple NHRP map statements to map the physical IP of the destination GRE interface and the GRE IP. I was able to ping all ends of the GRE cloud but I cannot make OSPF/EIGRP work even if I have mapped the multicast IP as well. I tried to use EIGRP  neighbor statements to see if the EIGRP peers would come up using unicast and it did but not when multicast was used. I am having a hard time looking for the right document as everything is referring to DMVPN.

Any idea if this is a valid configuration or design?

Thanks,

John

[jpl861]

I tried to use BGP and it totally worked fine. But any multicast traffic is not working. I checked Wireshark and packets are being encapsulated on a GRE packet twice.

Router1:

interface FastEthernet0/0
 ip address 21.1.77.1 255.255.255.0

interface Tunnel10
 ip address 1.0.0.1 255.255.255.0
 no ip redirects
 ip mtu 1400
 ip pim dense-mode
 ip nhrp authentication cisco10
 ip nhrp map 1.0.0.3 21.97.10.1
 ip nhrp map multicast 1.0.0.3
 ip nhrp map 1.0.0.2 203.177.7.1
 ip nhrp map multicast 1.0.0.2
 ip nhrp network-id 10
 ip tcp adjust-mss 1300
 tunnel source FastEthernet0/0
 tunnel mode gre multipoint
 tunnel key 10

Router2:

interface FastEthernet0/0
 ip address 203.177.7.1 255.255.255.0

interface Tunnel10
 ip address 1.0.0.2 255.255.255.0
 no ip redirects
 ip mtu 1400
 ip pim dense-mode
 ip nhrp authentication cisco10
 ip nhrp map 1.0.0.1 21.1.77.1
 ip nhrp map multicast 1.0.0.1
 ip nhrp map 1.0.0.3 21.97.10.1
 ip nhrp map multicast 1.0.0.3
 ip nhrp network-id 10
 ip tcp adjust-mss 1300
 tunnel source FastEthernet0/0
 tunnel mode gre multipoint
 tunnel key 10

Router3:

interface FastEthernet0/0
 ip address 21.97.10.1 255.255.255.0

interface Tunnel10
 ip address 1.0.0.3 255.255.255.0
 no ip redirects
 ip pim dense-mode
 ip nhrp authentication cisco10
 ip nhrp map 1.0.0.1 21.1.77.1
 ip nhrp map multicast 1.0.0.1
 ip nhrp map 1.0.0.2 203.177.7.1
 ip nhrp map multicast 1.0.0.2
 ip nhrp network-id 10
 tunnel source FastEthernet0/0
 tunnel mode gre multipoint
 tunnel key 10