Nonstop Active Routing Bfd Support - Juniper EX9200 Features Manual

High Availability Feature Guide for EX9200 Switches

Nonstop Active Routing BFD Support

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Nonstop active routing supports the Bidirectional Forwarding Detection (BFD) protocol,
which uses the topology discovered by routing protocols to monitor neighbors. The BFD
protocol is a simple hello mechanism that detects failures in a network. Because BFD is
streamlined to be efficient at fast liveness detection, when it is used in conjunction with
routing protocols, routing recovery times are improved. With nonstop active routing
enabled, BFD session states are not restarted when a Routing Engine switchover occurs.
NOTE: BFD session states are saved only for clients using aggregate or static
routes or for BGP, IS-IS, OSPF/OSPFv3, PIM, or RSVP.
When a BFD session is distributed to the Packet Forwarding Engine, BFD packets continue
to be sent during a Routing Engine switchover. If nondistributed BFD sessions are to be
kept alive during a switchover, you must ensure that the session failure detection time
is greater than the Routing Engine switchover time. The following BFD sessions are not
distributed to the Packet Forwarding Engine: multihop sessions, tunnel-encapsulated
sessions, and sessions over integrated routing and bridging (IRB) interfaces.
NOTE: BFD is an intensive protocol that consumes system resources.
Specifying a minimum interval for BFD less than 100 ms for Routing
Engine-based sessions and 10 ms for distributed BFD sessions can cause
undesired BFD flapping. The
BFD liveness detection parameter.
Depending on your network environment, these additional recommendations
might apply:
For large-scale network deployments with a large number of BFD sessions,
specify a minimum interval of 300 ms for Routing Engine-based sessions,
and 100 ms for distributed BFD sessions.
For very large-scale network deployments with a large number of BFD
sessions, contact Juniper Networks customer support for more information.
For BFD sessions to remain up during a Routing Engine switchover event
when nonstop active routing is configured, specify a minimum interval of
10 seconds for Routing Engine-based sessions. For distributed BFD sessions
with nonstop active routing configured, the minimum interval
recommendations are unchanged and depend only on your network
deployment.
minimum-interval configuration statement is a
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