Re: [OSPF] OSPF GR and BFD operability

"Les Ginsberg (ginsberg)" <> Tue, 25 August 2015 15:28 UTC

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From: "Les Ginsberg (ginsberg)" <>
To: "Acee Lindem (acee)" <>, Anil Raj <>, OSPF WG List <>
Thread-Topic: [OSPF] OSPF GR and BFD operability
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Date: Tue, 25 Aug 2015 15:27:59 +0000
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Subject: Re: [OSPF] OSPF GR and BFD operability
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X-List-Received-Date: Tue, 25 Aug 2015 15:28:05 -0000 Section 4.3<> is relevant here.


From: OSPF [] On Behalf Of Acee Lindem (acee)
Sent: Tuesday, August 25, 2015 7:54 AM
To: Anil Raj; OSPF WG List
Subject: Re: [OSPF] OSPF GR and BFD operability

Hi Anil,

OSPF and OSPFv3 graceful restart pre-dated BFD so this wasn’t explicitly covered. However, given that the intension is that the data plane is preserved during restart, an implementation could interpret this as a topology change and terminate helper mode as documented in section 3.2 of RFC 3623.
Hope this helps,

From: OSPF <<>> on behalf of Anil Raj <<>>
Date: Tuesday, August 25, 2015 at 10:19 AM
To: OSPF WG List <<>>
Subject: [OSPF] OSPF GR and BFD operability


I need clarification on the behavior when BFD notifies remote inactivity for a OSPF session, when OSPF neighbor is undergoing Graceful restart? OSPF router in helper mode will ideally inactivate the restarting neighbor only after grace period, and if BFD notifies neighbor down to OSPF, should the adjacency be terminated? If not, will it cause a blackhole for the entire grace period if the neighbor is actually down?

Appreciate if you can help here.