Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 978)

948 Multi-Service IronWare Switching Configuration Guide
53-1003036-02
Configuring BFD for RSVP-TE LSPs
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If the number of BFD sessions has reached the su pop rt ed maximum for the device, no MPLS
Echo Reply or BFD control packet is sent. The ingress LSR will retry.
Because the source IP address cannot be changed for an MPLS BFD session after the session has
come up, the LSR-ID is used as the source IP address for all MPLS BFD packets. This ensures that
the session will not go down when an LSP path switch occurs.
BFD session down behavior
When a BFD session for an LSP goes down on an ingress LSR because the BFD detection time has
expired, one of the following path switchovers will be triggered; from the protected path to the
detour path, or from the primary path to the secondary path. In configurations with no alternative
path, the LSP is brought down and the BFD session is deleted. The LSP then follows the normal
retry procedures to come back up. On an egress LSR, a down BFD session does not have any
impact on the RSVP session.
AdminDown State
The AdminDown mechanism in BFD is intended to signal that the BFD session is being taken down
for administrative purposes, and the session state is not indicative of the activity of the data path.
Therefore, a system should not indicate a connectivity failure to a client if either the local session
state or the remote session state (if known) transitions to AdminDown when that client has an
independent means of activity detection (typically, control protocols).
If a client does not have any independent means of activity detection, a system should indicate a
connectivity failure to a client, and assume the semantics of Down state, if either the local or
remote session state transitions to AdminDown. Otherwise, the client will not be able to determine
whether the path is viable, if not unfortunate results may occur.
Reaction to BFD Session State Changes
If a BFD session transitions from Up state to AdminDown, or the session transitions from Up to
Down because the remote system is indicating that the session is in state AdminDown, clients
should not take any control protocol action.
BFD session deletion
A BFD session is deleted when any of the following events occur:
• An LSP goes down
• BFD is disabled for the LSP
• BFD is disabled for all LSPs (using the global configuration)
These events are described in the following sections.
Enabling BFD for RSVP-TE LSPs at the global level
When using BFD for RSVP-TE LSPs, you must configure BFD globally at the router mpls level. You
can also use this configuration to set new default values for the transmit interval, receive interval,
and for the detection time multiplier, as shown.
Brocade(config)# router mpls
Brocade(config-mpls)# bfd
Brocade(config-mpls)# min-tx 500 min-rx 500 multiplier 5
Syntax: [no] min-tx transmit-time min-rx receive-time multiplier number