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MPLS
Automatic Bandwidth Allocation for RSVP LSPs
Enabling and Disabling Auto-Bandwidth Allocation on an LSP
This section discusses an auto-bandwidth hierarchy configurable in the config>router>mpls>lsp
context.
Adding auto-bandwidth at the LSP level starts the measurement of LSP bandwidth described in
Measurement of LSP Bandwidth on page 33
based on the triggers described in
When an LSP is first established, the bandwidth reserved along its primary path is controlled by
the bandwidth parameter in the config>router>mpls>lsp>primary context, whether or not the
LSP has auto-bandwidth enabled. When auto-bandwidth is enabled and a trigger occurs, the
system will attempt to change the bandwidth of the LSP to a value between min-bandwidth and
max-bandwidth, which are configurable values in the lsp>auto-bandwidth context. min-
bandwidth is the minimum bandwidth that auto-bandwidth can signal for the LSP and max-
bandwidth is the maximum bandwidth that can be signaled. The user can set the min-bandwidth
to the same value as the primary path bandwidth but the system will not enforce this restriction.
The system will allow:
•
•
•
•
All of the auto-bandwidth adjustments discussed are performed using MBB procedures.
Auto bandwidth can be added to an operational LSP at any time (without the need to shut down the
LSP or path), but no bandwidth change occurs until a future trigger event. Auto bandwidth may
also be removed from an operational LSP at any time and this causes an immediate MBB
bandwidth change to be attempted using the configured primary path bandwidth.
Note that changing the configured bandwidth of an auto-bandwidth LSP has no immediate affect,
it will only matters if the LSP/path goes down (due to failure or administrative action) and comes
back up or if auto-bandwidth is removed from the LSP. The operator can force an auto-bandwidth
LSP to be resized immediately to an arbitrary bandwidth using the appropriate tools commands.
Page 32
No min-bandwidth to be configured. In this case, the implicit minimum is 0 Mbps
No max-bandwidth to be configured, as long as overflow-triggered auto-bandwidth is not
configured. In this case, the implicit maximum is infinite (effectively 100 Gbps).
The configured primary path bandwidth to be outside the range of min-bandwidth to max-
bandwidth.
auto-bandwidth parameters can be changed at any time on an operational LSP; in most
cases the changes have no immediate impact but subsequent sections will describe some
exceptions
and allows auto-bandwidth adjustments to take place
Periodic Automatic Bandwidth Adjustment on page
7950 SR OS MPLS Configuration Guide
35.
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