Allied Telesis RAPIER I - Manual (Page 102)

102 BGP Enhancements Release Note
Software Version 2.8.1
C613-10477-00 REV B
BGP Enhancements
In Software Release 2.8.1, the following enhancements have been added to
Border Gateway Protocol functionality:
■ BGP Backoff Lower Threshold
■ BGP Peer and Peer Template Enhancements
■ Displaying Routes Learned from a Specific BGP Peer
This section describes the enhancements. The new and modified commands to
implement them are described in
Command Reference Updates .
BGP Backoff Lower Threshold
The BGP backoff utility allows other processes access to the memory resources
they need, without actually shutting BGP down unless it determines that BGP
has backed off for a prolonged period of time.
BGP backoff is disabled by default, however it automatically enables the first
time a peer is added.
Upper and Lower Thresholds
How to configure
BGP backoff
This Software Version adds a lower threshold for BGP backoff, which allows
BGP to remain backed off until the system memory is much less utilised. To set
this threshold, use the new low parameter in the command:
set bgp backoff[=20..100] [basetime=0..100]
[consecutive=0..1000] [low=15..99] [multiplier=1..1000]
[step=1..1000] [totallimit=0..1000]
Thresholds Together, the backoff and low parameters create upper and lower thresholds
which trigger and maintain BGP backoff. When memory usage exceeds the
upper threshold, BGP backoff is triggered. BGP continues to back off until
memory usage falls below the lower threshold. At this stage BGP begins
processing again, unless the total or consecutive backoff limits were reached.
Both threshold values represent a percentage of total system memory use. The
upper threshold is set using the backoff parameter, and must be a higher
percentage than the lower threshold. The lower threshold is set using the low
parameter, and must be a lower percentage than the upper threshold. The
backoff
and low parameters cannot be set to the same value.
The default value for the backoff parameter is 95%, while the default value for
the low parameter is 90%.
As the router or switch will not allow the backoff parameter value to be set
below the low parameter, we recommend that you always adjust these
parameters in the same command. For example:
set bgp backoff=88 low=84
Consecutive
backoffs
If BGP gets to the end of the backoff period and system memory is still above
the lower memory use threshold, BGP backs off immediately without
performing any processing. Such backoffs are called consecutive backoffs. The
consecutive backoffs default limit is now 5.