Cisco Catalyst 4500 Series Configuration Guide

37-15
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
OL-25340-01
Chapter 37 Configuring Bidirection Forwarding Detection
How to Configure Bidirectional Forwarding Detection
the forwarding path on the remote (neighbor) system without involving the remote system, there is an
opportunity to improve the interpacket delay variance, thereby achieving quicker failure detection times
than when using BFD Version 0 with BFD control packets for the BFD session.
Echo mode is described as without asymmetry when it is running on both sides (both BFD neighbors are
running echo mode).
Prerequisites
BFD must be running on all participating switches.
Before using BFD echo mode, you must disable the sending of Internet Control Message Protocol
(ICMP) redirect messages by entering the no ip redirects command, in order to avoid high CPU
utilization.
The baseline parameters for BFD sessions on the interfaces over which you want to run BFD sessions to
BFD neighbors must be configured. See the “Configuring BFD Session Parameters on the Interface”
section on page 37-8 for more information.
Restrictions
BFD echo mode which is supported in BFD Version 1.
This section contains the following configuration tasks for BFD echo mode:
• Configuring the BFD Slow Timer, page 37-15
• Disabling BFD Echo Mode Without Asymmetry, page 37-16
Note BFD echo mode does not work in conjunction with Unicast Reverse Path Forwarding (uRPF)
configuration. If BFD echo mode and uRPF configurations are enabled, then the sessions will flap.
Configuring the BFD Slow Timer
The steps in this procedure show how to change the value of the BFD slow timer. Repeat the steps in this
procedure for each BFD switch.
To configure the BFD slow timer, perform this task:
Command or Action Purpose
Step 1
enable
Switch> enable
Enables privileged EXEC mode.
• Enter your password if prompted.
Step 2
configure terminal
Switch# configure terminal
Enters global configuration mode.
Step 3
bfd slow-timer milliseconds
Switch(config)# bfd slow-timer 12000
Configures the BFD slow timer.
Step 4
end
Switch(config)# end
Exits global configuration mode and returns
the switch to privileged EXEC mode.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E