Posted on October 16, 2017 2:44 pm
 |  Asked by Alex samad
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 interface Ethernet34

   switchport access vlan 18

   bfd interval 200 min_rx 200 multiplier 3

   no ip ospf bfd

   spanning-tree portfast

   spanning-tree bpdufilter enable


interface Vlan18


   ip address

   ip ospf bfd

   ip ospf priority 200

   ip ospf authentication message-digest

   ip ospf message-digest-key 1 md5 7 <>



So I have 1 port in vlan18, should I put all the config on the ethernet interface or keep as it is.


Also should I have the bfd on the ethernet or the vlan interface ?



Posted by Alexandru
Answered on October 19, 2017 1:59 pm

Hi Alex,

The OSPF configuration depends on your network topology and environment but it should work both ways without any issues.

However the timers configuration for BFD should be on the same interface where you configure the protocol.

In your example “bfd interval 200 min_rx 200 multiplier 3” will not take affect as the interface itself is not a routed port participating in a routing protocol. Please configure the BFD timers under the interface Vlan 18 and check on the remote peer if the timers have indeed changed.

I ran a quick test in the lab and you should see the following:

— on local switch I configured 500/1000 timers

interface Vlan10

  ip address

  bfd interval 500 min_rx 1000 multiplier 3

  ip ospf bfd

— on remote switch you should see the timers change

se302...13:50:32(config)# show bfd neighbors detail Peer

Addr, Intf Ethernet23, State Up


Registered protocols: ospf

Last packet: Version: 1 

             Diagnostic: 0 State bit: Up 

             Demand bit: 0 Poll bit: 0 

             Final bit: 0 Multiplier: 3 

             Length: 24 My Discr.: 1 

             Your Discr.: 1 Min tx interval: 500000 

             Min rx interval: 1000000 Min Echo interval: 1000000

Hope this helps answer your question.

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