Hi experts,
I was studying on my lab rack and I was actually playing with DMVPN but suddenly decided to try eBGP peering on VPNv4. I have two DMVPN hubs (R1 and R2) and one spoke (R11). I used dual-home single-VPN design so all the tunnels are in the same subnet 192.168.12.0/24. The devices are having .1, .2 and .11 respectively.
Then I was building BGP peering on the 192.168.12.0/24 subnet. Here is when I found something very interesting. As soon as the VPNv4 peering established, the routers would add a /32 host route of the peer and it is shown as "connected" type.
R1(config-router)#do sh ip route 192.168.12.11
Routing entry for 192.168.12.11/32
Known via "connected", distance 0, metric 0 (connected, via interface)
Redistributing via eigrp 100
Advertised by eigrp 100
Routing Descriptor Blocks:
* directly connected, via Tunnel0
Route metric is 0, traffic share count is 1
R11#sho ip route 192.168.12.1
Routing entry for 192.168.12.1/32
Known via "connected", distance 0, metric 0 (connected, via interface)
Redistributing via eigrp 100
Advertised by eigrp 100
Routing Descriptor Blocks:
* directly connected, via Tunnel12
Route metric is 0, traffic share count is 1
Before it was established, it is shown correctly as the /24 route
R1#sh ip route 192.168.12.11
Routing entry for 192.168.12.0/24
Known via "connected", distance 0, metric 0 (connected, via interface)
Redistributing via eigrp 100
Routing Descriptor Blocks:
* directly connected, via Tunnel0
Route metric is 0, traffic share count is 1
Here is with debug. As you can see the route is injected as soon as the peering is formed
*Jun 19 20:43:23.539: %BGP-5-ADJCHANGE: neighbor 192.168.12.11 Up
R1(config-router-af)#
*Jun 19 20:43:23.540: RT: updating connected 192.168.12.11/32 (0x0):
via 0.0.0.0 Tu0
*Jun 19 20:43:23.540: RT: add 192.168.12.11/32 via 0.0.0.0, connected metric [0/0]
*Jun 19 20:43:23.566: RT: updating eigrp 192.168.12.1/32 (0x0):
via 192.168.12.11 Tu0
*Jun 19 20:43:23.566: RT: rib update return code: 17
Any ideas? Thanks!
