Re: Point-to-Point with Multipoint

From: Donny MATEO (donny.mateo@sg.ca-indosuez.com)
Date: Tue Oct 22 2002 - 22:41:09 GMT-3

this is old issue,
the only way I can tell you is the spoke will consider it self as attached to a Broadcast / Non
broadcast area and will do DR election and such.
While the hub on the other hand will consider it self to be attached to a Point to Multipoint
interface and thus not requiring a DR election.
What you have here is a situation called LSA discrepancy. The LSA sent by the Hub to the spoke is
not exactly what it expect it to be, cause it expect to see the FR cloud as a NBMA network...well
what the hub sent it is it's a multipoint, so spoke router and hub router would be confused saying "
what the hell is going on here.. ok don't trust this LSA".
 Thus all the route won't be installed. Please check the technical tips on why some ospf router area
in the database and not in the routing table. You should have a pretty good idea after that.
To save you the trouble here is the link :
http://www.cisco.com/warp/public/104/26.html

Donny

                                                                                                                                       
                      "Banlan Chen"
                      <banlan.chen@lyco To: ccielab@groupstudy.com, "Hunt Lee" <ciscoforme3@yahoo.com.au>
                      s.com> cc:
                      Sent by: Subject: Re: Point-to-Point with Multipoint
                      nobody@groupstudy
                      .com
                                                                                                                                       
                                                                                                                                       
                      23-10-2002 02:25
                      Please respond to
                      "Banlan Chen"
                                                                                                                                       
                                                                                                                                       

Hi Hunt,

I met same situation in my lab. The net type of your hub is point-to-multipoint and the spoke is
non-broadcast (cause you didn't use network statement, point-to-multipoint subint's default ospf net
type is non-broadcast). They can establish adj ("show ip ospf nei" is full), but actually no lsa
exchange so there is no routes in routing table. I couldn't finf any explaination, so only thing I
can do is set same network type between two ospf peers according Doyle I.

Banlan 

--

On Tue, 22 Oct 2002 23:43:36
 Hunt Lee wrote:
>Hello,
>
>Are Point-to-Point and Point-to-Multipoint the only compatible pair of
>Ospf Network Types (besides a type to itself)?
>
>I have tested this in a hub & spoke topology, the hub has 2
>point-to-point sub-interfaces (by "serial 0.1 point-to-point" & "serial
>0.2 point-to-point", and when I creates the point-to-multipoint spoke
>by "ip ospf network point-to-multipoint", everything is working as
>expected.
>
>However, leaving the hub the same, if I create the point-to-multipoint
>spoke by "interface serial 0.1 multipoint" command rather than using
>"ip ospf network point-to-multipoint" command, the OSPF adjacency would
>form, but never exchange tables.
>
>In both cases, I have set the Hello Interval at the hub's
>point-to-point sub-interface to match the spokes by "ip ospf
>hello-interval 30".
>
>Kind Regards,
>Hunt Lee
>
>http://careers.yahoo.com.au - Yahoo! Careers
>- 1,000's of jobs waiting online for you!
>

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