Cisco CRS Configuration Manual page 209

Implementing MPLS Traffic Engineering
Table 6: Automatic Bandwidth Variables
Function
Application frequency
Requested bandwidth
Collection frequency
Highest collected
bandwidth
Delta
The output rate on a tunnel is collected at regular intervals that are configured by using the application
command in MPLS-TE auto bandwidth interface configuration mode. When the application period timer
expires, and when the difference between the measured and the current bandwidth exceeds the adjustment
threshold, the tunnel is reoptimized. Then, the bandwidth samples are cleared to record the new largest output
rate at the next interval.
When reoptimizing the LSP with the new bandwidth, a new path request is generated. If the new bandwidth
is not available, the last good LSP continues to be used. This way, the network experiences no traffic
interruptions.
If minimum or maximum bandwidth values are configured for a tunnel, the bandwidth, which the automatic
bandwidth signals, stays within these values.
When more than 100 tunnels are auto-bw enabled, the algorithm will jitter the first application of every
Note
tunnel by a maximum of 20% (max 1hour). The algorithm does this to avoid too many tunnels running
auto bandwidth applications at the same time.
Command Description
application command Configures how often the
tunnel bandwidths
changed for each tunnel.
The application period is
the period of A minutes
between the bandwidth
applications during which
the output rate collection
is done.
bw-limit command Limits the range of
bandwidth within the
automatic-bandwidth
feature that can request a
bandwidth.
Configures how often the
auto-bw collect
command tunnel output rate is
polled globally for all
tunnels.
— You cannot configure this
value.
— You cannot configure this
value.
Cisco IOS XR MPLS Configuration Guide for the Cisco CRS Router, Release 5.1.x
MPLS-TE Automatic Bandwidth
Default Value
24 hours
0 Kbps
5 min
—
—
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