Why Are OSPF Neighbors Stuck in Exstart/Exchange State?

Why Are OSPF Neighbors Stuck in Exstart/Exchange State?  [IP Routing] – Cisco Systems.

An actual recreation of this problem is described in this section.

12a_01.gif

Router 6 and Router 7 in the above topology are connected via Frame Relay and Router 6 has been configured with 5 static routes redistributed into OSPF. The serial interface on Router 6 has the default MTU of 1500, while the serial interface on Router 7 has an MTU of 1450. Each router configuration is shown in the table below (only necessary configuration information is shown):

Router 6 Configuration Router 7 Configuration
interface Serial2
 !--- MTU sets to it's default value of 1500. 
no ip address
no ip directed-broadcast
encapsulation frame-relay
no ip mroute-cache
frame-relay lmi-type ansi
!
interface Serial2.7 point-to-point
ip address 170.170.11.6 255.255.255.0
no ip directed-broadcast
frame-relay interface-dlci 101
!
router ospf 7
redistribute static subnets
network 170.170.11.0 0.0.0.255 area 0

ip route 192.79.34.0 255.255.255.0 Null0
ip route 192.79.35.0 255.255.255.0 Null0
ip route 192.79.36.0 255.255.255.0 Null0
ip route 192.79.37.0 255.255.255.0 Null0
ip route 192.79.38.0 255.255.255.0 Null0
!
interface Serial0
mtu 1450
no ip address
no ip directed-broadcast
encapsulation frame-relay
frame-relay lmi-type ANSI

!
interface Serial0.6 point-to-point
ip address 170.170.11.7 255.255.255.0
no ip directed-broadcast
frame-relay interface-dlci 110!
!

router ospf 7
network 170.170.11.0 0.0.0.255 area 0

 

The show ip ospf neighbor command output for each router is:

 

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