Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 400)

376 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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RSVP-TE Hello
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Brocade(config-mpls)# policy
Brocade(config-mpls-policy)# backup-retry-time 100
Syntax: [no] backup-retry-time interval
The interval parameter valid range is: [10 - 600] seconds.
Use the [no] form of this command to revert to the default of 30 seconds.
RSVP-TE Hello
TABLE 44
Term Meaning
LSP Label Switched Path
MPLS Multiprotocol Label Switching
RESV Reserve
RSVP Resource Reservation Protocol
TE Traffic Engineering
RSVP-TE Hello glossary
The RSVP-TE Hello feature is an optional extension to RSVP-TE protocols to detect neighbor down
scenarios. It makes use of Hello messages as keepAlive poll mechanism between RSVP peers on a
link.
A failure along the path of a signaled RSVP-TE LSP can remain undetected for as long as two
minutes or longer (reservation or RESV time-out). 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 head end tunnels to signal or re-signal LSPs, tunnels
may fail to come up for several minutes thereby negatively affecting convergence time.
Hello messages enable RSVP nodes to detect when a neighboring node is not reachable. When
RSVP-TE Hello protocol notices that a neighbor is not responding, it treats it as a neighbor down
case (link layer communication failure) and either deletes the LSP state or reroutes it based on the
type of LSP. This action frees the node's resources to be reused by other LSPs.
A Hello message is sent out periodically to each RSVP peer on a link. If no response is received
from the peer within a specified period of time, then the peer is announced “dead”(down). RSVP
LSPs going over that peer must either be torn down or re-routed based on the nature of the LSPs.
This Hello mechanism is intended for use between immediate neighbors. Hello processing between
two neighbors supports independent selection of configurations of failure detections intervals.
The configuration of Hello message is completely optional. All the messages may be ignored by
nodes which do not wish to participate in Hello message processing. This feature complies with
RFC 3209, section 5 (Hello Extension) other than the default hello-interval time which is different in
Brocade’s implementation.
By default, this feature is disabled.