Reference Guide

Bidirectional Forwarding Detection (BFD) | 155
Figure 8-3. BFD State Machine
Important Points to Remember
• Dell Networking OS supports a maximum of 128 sessions per stack unit at 200 minimum transmit and
receive intervals with a multiplier of 3, and 64 sessions at 100 minimum transmit and receive intervals
with a multiplier of 4.
• BFD must be enabled on both ends of a link.
• Demand mode, authentication, and the Echo function are not supported.
• BFD is not supported on multi-hop and virtual links.
• Protocol Liveness is supported for routing protocols only.
• Dell Networking OS supports only OSPF, IS-IS, BGP, and VRRP protocols as BFD clients.
Configuring Bidirectional Forwarding Detection
The remainder of this chapter is divided into the following sections:
• Configuring BFD for OSPF
• Configuring BFD for IS-IS
• Configuring BFD for BGP
• Configuring Protocol Liveness
• Troubleshooting BFD
Configuring BFD for OSPF
BFD for OSPF is only supported on the S5000 platform.
When using BFD with OSPF, the OSPF protocol registers with the BFD manager. BFD sessions are
established with all neighboring interfaces participating in OSPF. If a neighboring interface fails, the BFD
agent on the stack unit notifies the BFD manager, which in turn notifies the OSPF protocol that a link state
change occurred.
Down
Init
Up
Up, Admin Down, Timer
Init
Down
Admin Down,
Timer
Admin Down,
Down,
Timer
D
own
Init, Up
Up, I
nit
the packet received
current session state