CCIE V5 : R&S ADVANCED TECHNOLOGY LABS : OSPF DR/BDR Election Manipulation

TASK : Configure DMVPN routers to ensure that R5 is elected as the DR.


I am
leaving with default IP OSPF Priority "1" for the spoke routers and priority has been configured 255 for the HUB R5.

 

One of the spoke router
getting elected as a DR and R5 elected as a BDR but Our TASK is R5 should be a DR
and that’s why we have configured priority 255.

 

 

Can I configure the priority
0 for the all spoke routers to achieve this task?

 

Current config:

R5#SHOW IP OS INT TU 0 | i State

  Internet Address 155.1.0.5/24, Area 0, Attached via Network Statement

  Transmit Delay is 1 sec, State BDR, Priority 255

 

R5#show run int tu 0

Building configuration...

 

Current configuration : 391 bytes

!

interface Tunnel0

 ip address 155.1.0.5 255.255.255.0

 no ip redirects

 ip mtu 1400

 ip nhrp authentication NHRPPASS

 ip nhrp map multicast dynamic

 ip nhrp network-id 1

 ip tcp adjust-mss 1360

 ip ospf network broadcast

 ip ospf priority 255

 delay 1000

 tunnel source GigabitEthernet1/0.100

 tunnel mode gre multipoint

 tunnel key 150

 tunnel protection ipsec profile DMVPN_PROFILE

end

 

Comments

  • You should configure the spokes as priority 0. This will make them not even participate in the DR/BDR election. It will break OSPF if one of the spokes is elected DR. The DR/BDR is a non-preemptive processes meaning if there is an established DR and one with a better priority comes along it will not take over. 

  • Thank you.

    On 8 Aug 2015 00:28, "[email protected]" <[email protected]> wrote:

    You should configure the spokes as priority 0. This will make them not even participate in the DR/BDR election. It will break OSPF if one of the spokes is elected DR. The DR/BDR is a non-preemptive processes meaning if there is an established DR and one with a better priority comes along it will not take over. 




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  • and don't forget to clear the ospf processes - OSPF DR's only get re-elected if forced or by an outage - just giving them a 0 priority won't fix them if they're the DR - you'd have to clear that ospf process to make the hub take over

     

  • Yes, it is as you said. In OSPF there is no preemtion in DR/BDR election. You need to trigger the DR/BDR election somehow after we make any changes to priority.

    Thanks

     

    and don't forget to clear the ospf processes - OSPF DR's only get re-elected if forced or by an outage - just giving them a 0 priority won't fix them if they're the DR - you'd have to clear that ospf process to make the hub take over

     

     

  • There is preemption of multiple devices claim the DR role, which means set the DR value to be non-zero, but itself.


    Sent from my iPhone

    On Aug 10, 2015, at 10:43, Murad <[email protected]> wrote:

    Yes, it is as you said. In OSPF there is no preemtion in DR/BDR election. You need to trigger the DR/BDR election somehow after we make any changes to priority.

    Thanks

     

    imagewhiskeytown:

    and don't forget to clear the ospf processes - OSPF DR's only get re-elected if forced or by an outage - just giving them a 0 priority won't fix them if they're the DR - you'd have to clear that ospf process to make the hub take over

     

     




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