OSPF two way state issue

[gopal_4476]

Hi

Any one tell me while building adjacencies the ospf routers stuck up in two way state. wht would be the possible causes for this???

please try to solve my qustion.

Regards,

Gopal

[pkhatri]

Gopal,

That is not actually a problem. In fact, the TwoWay state is a legal state for neighbors to be in on multiaccess segments like Ethernet.

Consider a case where you have 4 routers on a LAN, A, B, C and D. A is the DR and B is the BDR. In such a case, router C's neighbor state for each neighbor will be as follows:

A - Full

B - Full

D - TwoWay

Each non-DR/non-BDR router will be in a Full state with the DR and BDR but will be in the TwoWay state with other non-DR routers. That simply means that the router has two-way communication with that neighbor but has not established a full adjacency with it, since the router will only establish adjacencies with the DR and BDR.

Hope that helps - pls rate the post if it does.

Paresh

[sundar.palaniappan]

This is the normal behavior of OSPF. In a multiaccess segment, OSPF routers form full adjacency only with the DR/BDR and two-way adjacency with the other routers.

Here's a document that explains with an example.

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094059.shtml

Hope that helps.

--Sundar