Configuring Bfd - OmniSwitch os6900 Network Configuration Manual

Configuring BFD

carried explicitly in the protocol, but rather, it is determined by the receiving system independently based
on the transmission interval (TX) and Detection Time Multiplier that have been negotiated.
The Detection Time Multiplier field value is approximately the number of packets that must be missed in
order to declare a session down. In Asynchronous mode, detection times can be different in each direc-
tion. The local system detection time in this mode equals the value of Detection Time Multiplier received
from the remote system multiplied by the negotiated transmission interval (TX). Because the time values
for BFD control packet transmissions and session detection are being constantly negotiated by the partici-
pating BFD peers, they can be changed at any time. They are also independent in each direction for each
session.
To change the rate at which BFD control packets are received, you can change the Required Min RX
Interval at any time to any value. This new value is sent in the next outgoing packet so that the remote
system can accommodate the changes made. Similarly, to change the rate at which BFD control packets
are transmitted, you can change the Desired Min TX Interval at any time to any value.
With some exceptions, a system cannot transmit control packets with an interval shorter than the larger
value of the TX interval and RX interval fields. This means that the system with the slower rate deter-
mines the BFD control packet transmission speed.
Configuring BFD
Configuring BFD for your network requires the following approach:
1
Optional: Configure a BFD session and related session parameter values. Once configured, enable all
participating BFD sessions before configuring BFD interoperability with the supported Layer 3 protocols.
See "Configuring BFD Session Parameters" on page 20-11
2
Configure BFD support for the Layer 3 protocols for which BFD establishes sessions. This implemen-
tation of BFD supports the IPv4 versions of BGP, OSPF, VRRP remote tracking, and static routes. See
"Configuring BFD Support for Layer 3 Protocols" on page 20-15
At the end of the chapter is a simple BFD network diagram with instructions on how it can be created on a
router-by-router basis. See
Configuring BFD Session Parameters
When a BFD session is created, default values are automatically set for these parameters. However, it is
possible to change these parameter values globally or for a specific BFD session. The following BFD
session parameter values are used to create, monitor, and negotiate BFD sessions between peers.
•
BFD session status (see
•
Transmit time interval (see
•
Receive time interval (see
•
Multiplier (see "Configuring the BFD Multiplier" on page
•
Echo interval (see
OmniSwitch AOS Release 7 Network Configuration Guide
"BFD Application Example" on page 20-23
"Configuring a BFD Session" on page
"Configuring the BFD Transmit Time interval" on page
"Configuring the BFD Receive Time Interval" on page
"Configuring the BFD Echo interval" on page
for more information.
for more information.
for more information.
20-12).
20-13).
20-13).
June 2013
Configuring BFD
20-12).
20-12).
page 20-11