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aceelindem / ietf-bgp-strict-mode

Git repository devoted to the development of draft-merciaz-idr-bgp-bfd-strict-mode
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Discuss when the BFD session is created #10

Closed jhaas-pfrc closed 3 weeks ago

jhaas-pfrc commented 3 weeks ago

Ketan raises the point that we discuss state machine interactions, but we don't go into enough detail to say when BFD needs to be started vs. BGP. We do discuss the other direction a bit in terms of the BFD holddown procedures.

aceelindem commented 3 weeks ago

Since an established BFD session is required for BGP, it would seem that BFD must be started for session establishment. If it is not started, this is either a misconfiguration or a bug.

jhaas-pfrc commented 3 weeks ago

The consideration is which kicks off which. BFD may not have a session established or even configured until BGP comes up in some implementations. However, given protocol delays, you may want to start BFD upon configuration without starting the BGP FSM yet.

Juniper ran into a form of this issue related to timeouts when the BFD sessions were started as part of protocol state actions. The goal for addressing this issue will be normative text that describes when the feature needs things to start, and potentially some helpful informative text about reasons to start things early or not.

jhaas-pfrc commented 3 weeks ago

Added a section covering this detail.