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martyyy
martyyy
Explorer III
April 11, 2025
Question

Clearing of the BGP Process

  • April 11, 2025
  • 3 replies
  • 1697 views

Hi, 

 

Whenever we edit the prefix-list or route-map associated to a specific BGP/OSPF neighbor, we have to clear the BGP/OPSF process to see the effects of the newly made changes. This adds an additional overhead every time we make changes.

We would like to understand if this is some kind of fail-safe mechanism or is there anything which we are missing in our configuration.

 

TIA :) 

3 replies

dingjerry_FTNT
Staff
dingjerry_FTNT
Staff
April 11, 2025

Hi @martyyy ,

 

I think that you need to soft reset BGP sessions at least:

 

https://community.fortinet.com/t5/FortiGate/Technical-Tip-BGP-soft-reset-to-refresh-BGP-routing-table/ta-p/190141

    Toshi_Esumi
    SuperUser
    Toshi_Esumi
    SuperUser
    April 11, 2025

    Filtering (prefix-list, route-map, etc.) changes won't change its routes (BGP) or LSAs (OSPF). Therefore it wouldn't trigger route/LSA updates to neighbors. You have to "soft" clear neighbor, as, etc. for BGP (uni-cast) or clear process for OSPF (multi-cast) to trigger advertisement or renegotiation of neighboring to re-filter routes/LSAs by the new filters you just set up.
    Unlike OSPF, which does periodic reflooding of LSAs every 30 min, BGP doesn't re-advertise routes without any route changes. 

    Toshi

      Tauri
      Tauri
      Explorer II
      April 11, 2025

      Hi, @martyyy!.
      It is possible if you use soft reset BGP session:

      execute router clear bgp <in|out> <neighbor-IP> soft

       

      Also you could try to use a soft-reconfiguration if supported to re-apply the updated route-map.

      config router bgp     config neighbor         edit x.x.x.x             set soft-reconfiguration enable         next     end end
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