OSPF flapping in mpls cloud

Unanswered Question
Aug 30th, 2010
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Hi techies,

i have to configure ospf over L2 mpls cloud, with 1 hub site all 20 remote spoke sites,

so i hv configured 20 sub-interface with dot1q trunking on physical interface at hub which connects to service provider mpls cloud,

Hub eg config :-

interface FastEthernet0/1.40
encapsulation dot1Q 40
ip address
ip ospf network point-to-multipoint
interface FastEthernet0/1.50
encapsulation dot1Q 50
ip address
  ip ospf network point-to-multipoint
interface FastEthernet0/1.51
encapsulation dot1Q 51
ip address
ip ospf network point-to-multipoint

and all remote sites interface as routed interface in their respective subnets .

i am using opsf network type point-to-multipoint,

but my ospf netwrok forms neighborship and then breaks and agian comes up,

debug shows dead timer expire.

please provide your comments.



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Pavol Golis Mon, 08/30/2010 - 13:48
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  • Cisco Employee,

Hi Mazhar,

Can you tell us what are you trying to achieve with point-to-multipoint broadcast OSPF network type ? Why you didn't left it on default as broadcast type or point-to-point ?

Point-to-multipoint with /30 masks doesn't make a lot of sense.


mazhar mahadik Mon, 08/30/2010 - 15:47
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Hi poval,

i started with ospf network type broadcast ( default one) but i saw neighborship flapping due to dead timer expiration, so later i moved all circuits to point-to-multipoint with intention of increasing dead interval and hello interval, but still i see flappings.




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