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FreeBSD to FreeBSD - OSPF over GRE over Ipsec transport mode (racoon) - Part 2
https://forum.ivorde.com/freebsd-to-freebsd-ospf-over-gre-over-ipsec-transport-mode-racoon-part-2-t877.html
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Author:  admin [ Sun Oct 30, 2011 7:36 am ]
Post subject:  FreeBSD to FreeBSD - OSPF over GRE over Ipsec transport mode (racoon) - Part 2

After setting up the IPSec tunnel between the two FreeBSD hosts (FreeBSD-A and FreeBSD-B) in part 1 (http://forum.ivorde.ro/freebsd-to-freebsd-ospf-over-gre-over-ipsec-transport-mode-racoon-part-1-t860.html using gre0 interfaces on both nodes, in this part I set up OSPF.

The relevant OSPFD configuration (quagga) on both nodes is simple. This is for FreeBSD-A node:
Code:
!
interface gre0
ip ospf hello-interval 2
ip ospf dead-interval 6
!
router ospf
ospf router-id A2.A2.A2.A2
redistribute static
network A2.A2.A2.A2/30 area 0.0.0.0
!




Ospf "hello" packets travel on the tunnel at 2 seconds intervals and ospf neighbour dead-interval is 6 seconds. These settings need to be identical on both nodes, otherwise ospf adjacency will not occur.

In case it fails, a good way to debug ospf adjacency is using tcpdump and looking at the data advertised by both OSPF nodes (can't call them "neighbours" yet).

Code:
FreeBSD-A# tcpdump -nnvi gre0
tcpdump: listening on gre3, link-type NULL (BSD loopback), capture size 96 bytes

13:23:15.745604 IP (tos 0xc0, ttl   1, id 42243, offset 0, flags [none], proto: OSPF (89), length: 68) A2.A2.A2.A2 > 224.0.0.5: OSPFv2, Hello, length: 48
   Router-ID: A2.A2.A2.A2, Backbone Area, Authentication Type: none (0)
   Options: [External]
     Hello Timer: 2s, Dead Timer 6s, Mask: 0.0.0.0, Priority: 1
     Neighbor List:
       B2.B2.B2.B2
13:23:16.002287 IP (tos 0xc0, ttl   1, id 35190, offset 0, flags [none], proto: OSPF (89), length: 68) B2.B2.B2.B2 > 224.0.0.5: OSPFv2, Hello, length: 48
   Router-ID: B2.B2.B2.B2, Backbone Area, Authentication Type: none (0)
   Options: [External]
     Hello Timer: 2s, Dead Timer 6s, Mask: 255.255.255.252, Priority: 128
     Neighbor List:
       A2.A2.A2.A2


The above output shows that FreeBSD-A node receives OSPF "hello" multicasts from FreeBSD-B and that it also sends. Both nodes use same "hello timer" and "dead-interval" settings.

Soon I will post more info on debugging quagga ospf peering.

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