From: Chris Lewis \(chrlewis\) (chrlewis@cisco.com)
Date: Tue Jul 19 2005 - 11:47:19 GMT-3
Just to add some detail to what others have already said.
One of the reasons P2mp non-broadcast came in to being was because lots
of TAC cases were created by people forgetting to put in the broadcast
keyword on the frame map statements. So p2mp non-broadcast is a way to
get p2mp to work with the neighbor command, making the broadcast
keyword on the map statement not necessary. In the exam this is used if
you are told not to use the broadcast keyword on the map statements.
Consider the following
R1:
interface Serial2/0
ip address 10.1.1.1 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint
no fair-queue
frame-relay map ip 10.1.1.2 122
no frame-relay inverse-arp
!
router ospf 1
log-adjacency-changes
network 10.1.1.1 0.0.0.0 area 0
neighbor 10.1.1.2 cost 100
R2:
interface Serial1/0
ip address 10.1.1.2 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint
no fair-queue
frame-relay map ip 10.1.1.1 221
no frame-relay inverse-arp
!
router ospf 1
log-adjacency-changes
network 10.1.1.2 0.0.0.0 area 0
neighbor 10.1.1.1 cost 100
R1 and R2 can ping each other's 10.0.0.0 interfaces, the network type is
p2mp and there is a neighbor statement, however the neighbors do not
form, as each router is still trying to send to the multicast address
with this network type, which leads to an encapsulation failed error
when the router tries to ship the packet over the frame link. To get
this setup to work, all you need do is change the network type to p2mp
non-broadcast, the neighbor statement takes effect, R1 and R2 start
sending unicast OSPF packets and neighbors form.
Chris
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian Lee
Sent: Monday, July 18, 2005 10:56 AM
To: ccielab@groupstudy.com
Subject: Re: Re: Ospf network types
hi,
I have the same question, could anyone gives us an explanation ?
Thanks
Lee.
----- Original Message -----
From: "Sharma, Mohit" <mohit.sharma@hp.com>
To: <ccielab@groupstudy.com>
Sent: Sunday, June 20, 2004 10:36 PM
Subject: Ospf network types
> HI All,
>
> Could somebody please explain the difference between using ospf
network
> type point-to-multipoint and point-to-multipoint nonbroadcast.
>
> The only difference I could read on the doc cd's was that with the
added
> nonbroadcast option you can use neighbor statement and assign costs to
> the neighbor spokes to distinguish between more or less preferred
links.
>
> But I did the same thing with just using the p2m option without using
> nonbroadcast and was able to assign the cost to the spokes.
> Then why do we need the nonbroadcast????
>
> Also another question-IF ospf should send ONLY unicast messages to the
> neighbor, then the only option would be to use nbma with neighbor
> command or is there any other option available which is send unicast??
>
> Thanx,
> Mohit.
>
>
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