Alcatel-Lucent 060321-10, Rev. B, Справочное руководство CLI

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OmniSwitch CLI Reference Guide March 2011 page 14-1
14 BFD Commands
Bidirectional Forwarding Detection (BFD) is a hello protocol, which can be configured to interact with
routing protocols for the detection of path failures and can reduce the convergence time in a network. BFD
is supported with the BGP, OSPF, VRRP, and Static Routes.
When BFD is configured and enabled, BFD sessions are created and timers are negotiated between BFD
neighbors. If a system does not receive a BFD control packet within the negotiated time interval, the
neighbor system is considered down. Rapid failure detection notices are then sent to the routing protocol,
which initiates a routing protocol recalculation. This process can reduce the time of convergence in a
network.
BFD can be operated in two different modes: Asynchronous mode with Echo enabled and Echo-Only
mode. Demand mode is not supported.
In Asynchronous mode, the systems continuously send BFD control packets between each other as part of
a BFD session. If there are no packets received for a minimum time interval negotiated between the
systems, then the neighbor system is considered down.
In Echo mode, a stream of BFD echo packets are transmitted in a forwarding path for which the neighbor-
ing system would loop the packets and send them back. If the number of packets transmitted is not echoed
back, then the system is declared down. Echo mode can be operated along with Asynchronous mode.
MIB information for the BFD commands is as follows:
Filename : ALCATEL-IND1-BFD-MIB
Module : ALCATEL-IND-BFD-MIB
A summary of the available commands is listed here:
Global BFD commands ip bfd admin-state
ip bfd transmit
ip bfd receive
ip bfd multiplier
ip bfd echo-interval
ip bfd interface
show ip bfd
show ip bfd sessions
show ip bfd sessions statistics