OSPF. Unsolicited /32 prefixes on directly connected interfaces

Created: Feb 19, 2019 17:42:55Latest reply: Feb 22, 2019 10:18:26 179 3 0 0
  Rewarded Hi-coins: 0 (problem resolved)

HI here!



I'm configuring OSPF on my s6720 switch. It works, but it looks strange. I just turned OSPF on the interface, like this:


ospf 1 router-id 10.8.0.100

 silent-interface all

 undo silent-interface Vlanif4010

 area 0.0.0.0

  network 10.8.3.0 0.0.0.255


interface Vlanif4010

 ip address 10.8.3.18 255.255.255.0

 ospf cost 100

 ospf network-type p2mp

 ospf dr-priority 0

 mpls

 mpls ldp


As you can see, all the neigbours have addresses in 10.8.3.0/24 network. 


Then it started to discover the neighbours, and exchanged the routing info.  Finally I checked my RIB and found a lot of prefixes like this: 10.8.3.XX/32


Why the OSPF process generates /32 for directly connected interface. It isn't a Loopback interface, just usual vlan with broadcast network there. 

I tried to change network type, but it didn't change the behaviour. Probaly it could be connected with MPLS on the interface, who knows? 

Any way, could you give me a hint how i could change this behaviour? I applied a prefix list to filter these prefixes, but I don't think this is a good resolution of the problem.


  • x
  • convention:

Featured Answers
Scott_Qing     Created Feb 21, 2019 14:26:13 Helpful(0) Helpful(0)

in p2mp network, ospf will create a host route for each neighbor, that is what you said 10.8.3.x/32 routes.
  • x
  • convention:

All Answers
sim_157  Visitor   Created Feb 20, 2019 14:48:41 Helpful(0) Helpful(0)

can you provide more details about your network topology and the routing-table?
  • x
  • convention:

Scott_Qing     Created Feb 21, 2019 14:26:13 Helpful(0) Helpful(0)

in p2mp network, ospf will create a host route for each neighbor, that is what you said 10.8.3.x/32 routes.
  • x
  • convention:

chenhui  Engager   Created Feb 22, 2019 10:18:26 Helpful(0) Helpful(0)

as @Scott_Qing said, in p2mp network, ospf will generate host routes for ospf neighbors,
  • x
  • convention:

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