From: Radoslav Vasilev (deckland@gmail.com)
Date: Fri Aug 11 2006 - 11:51:41 ART
Yes - I agree that prohibiting any interface configuration for the spokes is
a mistake - the only secure way to make sure it will always work is to make
the spokes ineligible for DR/BDR by setting priority=0.
About the network type - i realized that the neighbor command would be
necessary only when the media is not multicast capable - not when the
network type is non-broadcast. Thanks anyway!
Rado
On 8/11/06, Shanky <shankyz@gmail.com> wrote:
>
> Hi Radoslav,
>
> The key is under interface config of the spokes ..
>
> frame-relay map ip 173.1.125.5 105 broadcast
>
> so broadcast is allowed on the PVC between spoke & Hub , why you need the
> neighbor statements for ?
>
> Also, in my opinion , the solution should configure
> ip ospf priority 0 under interface configuration on the spokes ,
> configuring the Hub with high priority doesnt guarantee that it will be
> elected as DR.
>
> Hope it helps
>
> Shanky
>
>
>
>
> On 8/11/06, Radoslav Vasilev <deckland@gmail.com> wrote:
>
> > Hi Group,
>
> Can anyone shed some light of why the following setup actually works?
>
> The setup is from IEWBv3 lab 17, task 4.1 - basic ospf setup
>
> the underlying topology is frame-relay hub-and-spoke with R5 being the hub
> and R1 and R2 the spokes.
> The spokes use physical interfaces with manual FR mapping to R5. The hub
> uses In-ARP to go to the spokes.
>
>
> R5:
>
> interface Serial0/0.125 multipoint
> ip address 173.1.125.5 255.255.255.0
> ip ospf network non-broadcast
> ip ospf priority 255
> frame-relay interface-dlci 501
> frame-relay interface-dlci 502
>
> router ospf 100
> router-id 150.1.5.5
> log-adjacency-changes
> network 173.1.125.5 0.0.0.0 area 0
>
>
>
> R1:
> interface Serial0/0
> ip address 173.1.125.1 255.255.255.0
> no ip directed-broadcast
> encapsulation frame-relay
> no ip mroute-cache
> frame-relay map ip 173.1.125.2 105
> frame-relay map ip 173.1.125.5 105 broadcast
> no frame-relay inverse-arp
>
> router ospf 100
> network 173.1.125.1 0.0.0.0 area 0
>
>
> R2:
>
> interface Serial0/0
> ip address 173.1.125.2 255.255.255.0
> encapsulation frame-relay
> clock rate 64000
> frame-relay map ip 173.1.125.1 205
> frame-relay map ip 173.1.125.5 205 broadcast
> no frame-relay inverse-arp
>
> router ospf 100
> router-id 150.1.2.2
> log-adjacency-changes
> network 173.1.125.2 0.0.0.0 area 0
>
>
> Now the problem: area 0 has to be configured ove that FR segment - R1 and
> R2
> are not allowed any interface level commands to achieve that task.
> As R1 and R2 use physical interfaces, their ospf interface type is by
> default non-broadcast, so is the multipoint sub-iface of R5.
> We're not allowed neighbor commands anywhere as well.
>
> The IEsolution, as visible above includes configuring `ip ospf network
> non-broadcast` on R5.
> No neighbor commands, nothing else.
>
> 150.1.1.1 1 FULL/DR 00:01:47 173.1.125.1
> Serial0/0.125
> 150.1.2.2 1 FULL/DROTHER 00:01:54 173.1.125.2
> Serial0/0.125
>
> Any explenation what exactly happens so the non-broadcast neighbors
> actually
> become adjacent?
>
> Thanks in advance!
> Rado
>
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