Cisco Cisco IOS Software Release 12.2(33)SRE
MPLS Traffic Engineering—RSVP Hello State Timer
Prerequisites for MPLS Traffic Engineering—RSVP Hello State Timer
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Multiple Cisco IOS Releases
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Prerequisites for MPLS Traffic Engineering—RSVP Hello State
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Timer
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Configure Resource Reservation Protocol (RSVP) on routers.
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Enable Multiprotocol Label Switching (MPLS).
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Configure traffic engineering (TE) on routers.
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Enable hellos for state timeout.
Restrictions for MPLS Traffic Engineering—RSVP Hello State
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Timer
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Hellos for state timeout are dependent on graceful restart, if it is configured; however, graceful
restart is independent of hellos for state timeout.
restart is independent of hellos for state timeout.
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Unnumbered interfaces are not supported.
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Hellos for state timeout are configured on a per-interface basis.
Information About MPLS Traffic Engineering—RSVP Hello State
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To configure MPLS TE—RSVP Hello State Timer, you should understand the following concepts:
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Hellos for State Timeout
When RSVP signals a TE LSP and there is a failure somewhere along the path, the failure can remain
undetected for as long as two minutes. During this time, bandwidth is held by the non-functioning LSP
on the nodes downstream from the point of failure along the path with the state intact. If this bandwidth
is needed by headend tunnels to signal or resignal LSPs, tunnels may fail to come up for several minutes
thereby negatively affecting convergence time.
undetected for as long as two minutes. During this time, bandwidth is held by the non-functioning LSP
on the nodes downstream from the point of failure along the path with the state intact. If this bandwidth
is needed by headend tunnels to signal or resignal LSPs, tunnels may fail to come up for several minutes
thereby negatively affecting convergence time.
Hellos enable RSVP nodes to detect when a neighboring node is not reachable. After a certain number
of intervals, hellos notice that a neighbor is not responding and delete its state. This action frees the
node’s resources to be reused by other LSPs.
of intervals, hellos notice that a neighbor is not responding and delete its state. This action frees the
node’s resources to be reused by other LSPs.
Hellos must be configured both globally on the router and on the specific interface to be operational.