I have a bunch of 172.15.0.X /29 networks (17 at present time) that I want to interconnect in a full-meshed fashion using mGRE. As an edge devices I have Cisco851 routers. From various sources I gathered that I have to use VRF so that the tunnel knows where to send encapsulated data. And this is where my confusion starts. Here is what I do:
ip vrf tstvrf
rd 1:1
interface Tunnel10
ip vrf forwarding tstvrf
ip address 192.168.10.1 255.255.255.0
no ip redirects
keepalive 1 100
tunnel source FastEthernet4
tunnel mode gre multipoint
tunnel key 123
interface FastEthernet4
ip address 172.15.0.145 255.255.255.248
no ip redirects
no ip unreachables
no ip proxy-arp
duplex auto
speed auto
ip route vrf tstvrf 0.0.0.0 0.0.0.0 Tunnel10 172.15.0.233 global
ip route 172.15.0.0 255.255.255.0 172.15.0.150 ! next hop gateway
Where 172.15.0.233 is the address of another Cisco851 that also terminates mGRE.
ping 172.15.0.233 sou 172.15.0.145
Sending 5, 100-byte ICMP Echos to 172.15.0.233, timeout is 2 seconds:
Packet sent with a source address of 172.15.0.145
!!!!!
Tunnels do not work except for the case when I use pair mGRE-GRE. Here I see only one-way data flow from GRE to mGRE.
Some of the examples show mGRE with nhrp others with BGP4. Cisco851 have nether of them and tend to use static routes for the starters.
How can you help me?
