From: Alexei Monastyrnyi (alexeim@orcsoftware.com)
Date: Sun Oct 08 2006 - 11:26:46 ART
Hi.
Usual way is to set "ip ospf priority 0" on spokes' interfaces towards
hub router and "neighbor _spoke_IP_ " under ospf process of hub router
for each spoke. _spoke_IP_ is an IP address of spoke connected NBMA
interface, not an OSPF router ID of the neighbor. OSPF network type for
interfaces should be non-broadcast, if we mean to elect DR.
With this you don't have to use "priority keyword for neighbor statement.
Because of limited experience I can not provide an example where such a
keyword would be useful. Though it would be interesting to know... :-)
HTH
A.
david robin wrote:
> But the problem is that I try to make the hub router as DR and the other
> routers as Drother, but it can't be accomplished, could you tell me how can
> we accomplish this, also the documentation CD say the default priority is 0
> not 1 which makes me confused more.
>
>
>
>
> On 10/7/06, Alexei Monastyrnyi <alexeim@orcsoftware.com> wrote:
>
>> Seems like it is a whole lot of confusion here.. even in CiscoPress :-)
>>
>> From Cisco(r) OSPF Command and Configuration Handbook (CCIE Professional
>> Development)
>>
>>
>> 11-5. neighbor ip-address priority priority
>>
>> Syntax Description:
>>
>> *
>>
>> ip-address IP address of the OSPF neighbor. If a secondary
>> address is used on the interface, then the primary address must be
>> used with this command because OSPF will only form an adjacency
>> using the primary address.
>>
>> *
>>
>> priority The OSPF priority of the neighbor with the given IP
>> address. The range of values is 0 to 255. _The router with the
>> lowest OSPF priority on a network will be elected the DR for the
>> network._ A priority of zero means that the router is not eligible
>> to be elected the DR or Backup Designated Router (BDR). _The
>> default priority is 1_.
>>
>> Pay attention to _ ... _ statements :-) They seemingly messed up
>> priority in general and priority defaults for the particular command.
>>
>> From 12.3 DocCD
>>
>>
>>
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/iprrp
> _r/ip2_n1g.htm#wp1036543
>
>> *priority*/ number/
>>
>>
>>
>> (Optional) A number that indicates the router priority value of the
>> nonbroadcast neighbor associated with the IP address specified.* *The
>> default is 0. This keyword does not apply to point-to-multipoint
>> interfaces.
>>
>>
>> From what I can see on routers (IOS 12.3), for NBMA hub router with
>> this command applied towards spokes and spokes with default priority 1,
>> you accomplish nothing.
>>
>> Just a quick example. For hub router with lo0 9.9.4.4/32 and "ip ospf
>> priority 3" on NNBMA interface, after "clear ip ospf proc" on all three
>> boxes, I have, as expected.
>>
>> BB4#sh ip ospf nei
>>
>> Neighbor ID Pri State Dead Time Address Interface
>> 9.9.2.2 1 FULL/BDR 00:01:54 9.9.123.2 Serial0
>> 9.9.1.1 1 FULL/DROTHER 00:01:35 9.9.123.1 Serial0
>> BB4#sh run | beg router
>> router ospf 100
>> log-adjacency-changes
>> network 9.9.123.0 0.0.0.255 area 0
>> neighbor 9.9.123.2 priority 1
>> neighbor 9.9.123.1 priority 2
>>
>> After "clear ip ospf proc" on the hub router we have.
>> BB4#sh ip ospf nei
>>
>> Neighbor ID Pri State Dead Time Address Interface
>> 9.9.2.2 1 FULL/DR 00:01:53 9.9.123.2 Serial0
>> 9.9.1.1 1 FULL/BDR 00:01:59 9.9.123.1 Serial0
>>
>> Which is also expected. But I don't see any place where " neighbor ...
>> priority.. " comes into play.
>>
>> It is probably useful for more complex mesh than hub and spoke.
>>
>> A.
>>
>>
>> Noble, TN wrote:
>>
>>> The priority command does the same thing irrespective of the place it is
>>> applied. I mean, ip ospf priority 0 and neighbour 1.2.3.4 priority 0
>>> (optional and 0 is defaul) should do the same for us.
>>>
>>> Thank you,
>>>
>>> -Noble
>>>
>>>
>>> On 10/6/06, david robin <robindavi@gmail.com> wrote:
>>>
>>>
>>>> Dear all,
>>>> I m confused with neighbor priority command, I configured R1 as
>>>> frame-relay
>>>> hub, R2 and R5 as spokes. interfaces are non-broadcast so you must use
>>>> neighbor command.
>>>>
>>>> because R1 is the hub so prioriies of the two other routers must be set
>>>>
>> to
>>
>>>> 0
>>>> in order to make R1 as the DR, I know we can accomplish this by using
>>>>
>> ip
>>
>>>> ospf priority 0 under R2 and R5 serial interfaces.
>>>>
>>>> the question is does the neighbor priority command has any relation to
>>>> DR/BDR election, and if so what is the relation between it and ip ospf
>>>> priority 0, does ospf priority 0 override it or what ?
>>>>
>>>> and what is the use on neighbor priority command if is has no relation
>>>>
>> to
>>
>>>> DR/BDR election
>>>>
>>>> many thanks
>>>>
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>
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