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Sagar_Shah_9610's avatar
Sagar_Shah_9610
Icon for Nimbostratus rankNimbostratus
Apr 19, 2009

OSPF toggling on neighboring routers when BigIP is connected to them

Hello All,

 

 

I've BigIP 3400 LTM installed in HA mode (Active - Standby) at telecom carrier (See network diagram attached). OSPF module is licensed and running on BigIP.

 

 

It is running TMOS 9.4.5 HF2.

 

 

Past 10 days I've been observing that OSPF toggles frequently on Cisco neighbors i.e. there are adjacency changes frequently.

 

 

The occurrence of adjacency changes is quiet sporadic but when such an event happens subscribers start complaining about poor browsing and delayed ping responses.

 

 

I set the priority of ospf process on inside and outside vlans to '0'; Zero in order to ensure that BigIPs are never considered as a candidate during DR and BDR election. But the problem still persists.

 

 

I also disabled OSPF on standby unit. Yet it never helped.

 

 

I bypassed BigIPs and suprisingly, the OSPF toggles on Cisco routers/L3 switches stopped and it runs absolutely well.

 

 

The moment I get BigIP inline between Cisco gears, the OSPF toggling starts.

 

 

I would appreciate, your thoughts on this issue.

 

 

Sagar.

 

sagar.brit@gmail.com
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design
  • JRahm's avatar
    JRahm
    Icon for Admin rankAdmin
    Apr 20, 2009
    Anything in the LTM logs that line up with the debug information in the routers?
  • dennypayne's avatar
    dennypayne
    Icon for Employee rankEmployee
    Apr 20, 2009
    Believe it or not, I have actually seen a bug where if you are in vtysh and run 'show ip ospf route' it will occasionally cause an adjacency change. I think it is fixed in 9.4.6 and 9.4.7.

     

     

    I have also seen an issue where for some reason when a box becomes active it does not remove the 65535 cost metric that is usually automatically applied to the standby's configuration. This should also be fixed in newer releases.

     

     

    Denny