From: Peter van Oene (pvo@usermail.com)
Date: Sat Nov 29 2003 - 12:54:41 GMT-3
At 06:33 AM 11/29/2003, Hoyle, Anthony (AL) wrote:
>Ok Guys,
>
>Here is a good discussion:
>
>
>Why does OSPF act the way it does forming adjacencies over broadcast
>mediums /w multiple routers, hee hee hee.. I know for a multi-access
>medium such as Ethernet, routers running OSPF will form an adjacency with
>the DR and BDR all other Routers will have two-way adjacencies
>formed. Sometimes they will be full/drother sometimes they won't. I am
>aware of a router seeing itself in a neighbors hello packet , thus
>Confirming two-way communication and moving to the 2-way state.
This is normal OSPF behavior. Routers on a multi-access segment only
establish adjacencies with the DR and BDR. This minimizes flooding
requirements, and adjacency state on for those routers and thus is
considered a good thing.
>For example if you have a full mesh frame-relay cloud /w fifty routers
>(broadcast network type), there will be several pairs that will stay in
>two-way (no matter whether you use
>Priority or loopback to control the selection of the DR and BDR, or even
>if you set a few guys to 0-drother) I know Cisco says this is normal
>behavior, -but two-way state
>does not synchronize databases, what is the point -Redundancy? Of course
>as soon as one of the routers loses a BDR or DR it immediately transitions
>from the two-way to exstart from
>there to full. I guess exchanging LSA's over the cloud /w every other
>router might be nonsense, but I got it to work one time (about ten routers
>broadcast medium) -but that might be a fluke*
>
>Any thoughts? This is bothering me..i'm going to read the rfc again..
>
>
>
>Anthony Hoyle
>EDS
>WAN Infrastructure Analyst
>
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