Service Redundancy using BFD

Ankur Dubey <> Tue, 28 November 2017 02:47 UTC

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From: Ankur Dubey <>
To: "" <>
CC: Sami Boutros <>, Reshad Rahman <>
Subject: Service Redundancy using BFD
Thread-Topic: Service Redundancy using BFD
Thread-Index: AQHTZ/M82vlye4FAgk+FmQYa86ul9Q==
Date: Tue, 28 Nov 2017 02:47:30 +0000
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Hi all,

Please review and provide comments for the following draft:

Summary of draft:

This draft proposes a new BFD diag code via which a node running a BFD session with another node, can inform the other node after a BFD session times out, that it didn’t go down and did live through the failure.

Such notification is useful for a set of nodes providing Active/Standby redundancy. When these nodes are running multiple L2/L3/L4-L7 services  in non-revertive mode of redundancy, the standby node taking over as active for non-revertive services after BFD times out needs to indicate in the BFD packet that it outlived the other failed old active node. The new diag code will be used for this purpose. When this diag code is set in the BFD packets, it will provide an indication to the failed old active node that it MUST NOT activate the non-revertive services when it comes up.

For providing a per service level failover, a node activating certain non-revertive services needs to indicate that it is Active ONLY for those non-revertive services. This can be done by using a unique bitmap where each bit position is uniquely identifying a service. This unique bitmap is configured on all nodes by a network controller. When there is at least one non-revertive service for which a node is not active AND it is active for at least 1 non-revertive service, this node will set bits identifying the active services in the bitmap and send it in the payload of the BFD packet.