Bfd Packet Format - Dell S4820T Configuration Manual

receiving interface is faulty). The BFD manager notifies the routing protocols that are registered with it
(clients) that the forwarding path is down and a link state change is triggered in all protocols.
NOTE: A session state change from Up to Down is the only state change that triggers a link state
change in the routing protocol client.

BFD Packet Format

Control packets are encapsulated in user datagram protocol (UDP) packets. The following illustration
shows the complete encapsulation of a BFD control packet inside an IPv4 packet.
Figure 12. BFD in IPv4 Packet Format
Field Description
Diagnostic Code The reason that the last session failed.
State The current local session state. Refer to
Bidirectional Forwarding Detection (BFD)
BFD Sessions.
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