Re: [OSPF] OSPF GR and BFD operability

[Anil Raj <[e-mail]>]

I got it. Thanks Les for the details and reference.

Regards,
Anil

On Tue, Aug 25, 2015 at 10:11 PM, Acee Lindem (acee) <[e-mail]> wrote:

> I agree. Thanks Les for the reference to RFC 5882.
>
> Thanks,
> Acee
>
> From: "Les Ginsberg (ginsberg)" <[e-mail]>
> Date: Tuesday, August 25, 2015 at 12:29 PM
> To: Anil Raj <[e-mail]>
> Cc: Acee Lindem <[e-mail]>, OSPF WG List <[e-mail]>
> Subject: RE: [OSPF] OSPF GR and BFD operability
>
> Anil –
>
>
>
> IF BFD does NOT share fate w the Control plane then what you say is true.
>
>
>
> If BFD shares fate w the control plane then the behavior depends on the
> neighbor knowing that a restart is in progress. If neighbor knows this then
> the BFD down event can be ignored w minimal risk – otherwise you need to
> treat it as a real failure.
>
>
>
>    Les
>
>
>
>
>
> *From:* Anil Raj [mailto:[e-mail] <[e-mail]>]
> *Sent:* Tuesday, August 25, 2015 8:51 AM
> *To:* Les Ginsberg (ginsberg)
> *Cc:* Acee Lindem (acee); OSPF WG List
> *Subject:* Re: [OSPF] OSPF GR and BFD operability
>
>
>
> Thanks Acess, Les.
>
>
>
> So ideally it is recommended to tear down OSPF adjacency and signal
> topology change, and thus honor BFD notification in this case.
>
>
>
> Regards,
>
> Anil
>
>
>
> On Tue, Aug 25, 2015 at 8:57 PM, Les Ginsberg (ginsberg) <
> [e-mail]> wrote:
>
> https://www.rfc-editor.org/rfc/rfc5882.txt Section 4.3
> <https://www.rfc-editor.org/rfc/rfc5882.txt%20Section%204.3> is relevant
> here.
>
>
>
>    Les
>
>
>
>
>
> *From:* OSPF [mailto:[e-mail]] *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,
>
> Acee
>
>
>
>
>
>
>
> *From: *OSPF <[e-mail]> on behalf of Anil Raj <
> [e-mail]>
> *Date: *Tuesday, August 25, 2015 at 10:19 AM
> *To: *OSPF WG List <[e-mail]>
> *Subject: *[OSPF] OSPF GR and BFD operability
>
>
>
> Hi,
>
>
>
> 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.
>
>
>
> Regards,
>
> Anil
>
>
>
>