Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 459)

NOTE
Logging of errors is rate-limited to not more than one message for every two minutes. Some errors may
be lost due to this rate-limiting.
Sample log messages for various attribute errors are shown here.
Attribute length error (ignore the AS4_PATH)
SYSLOG: Sep 9 19:02:03:<11>mu2, BGP: From Peer 192.168.1.1 received invalid AS4_PATH
attribute length (3) - entire AS4_PATH ignored
Attribute flag error (ignore the AS4_PATH)
SYSLOG: Sep 9 19:02:03:<11>mu2, BGP: From Peer 192.168.1.1 received invalid AS4_PATH
attribute flag (0x40) - entire AS4_PATH ignored
Confederation segments after AS_SEQ/AS_SET (ignore the AS4_PATH)
SYSLOG: Sep 9 19:02:03:<11>mu2, BGP: From Peer 192.168.1.1 received invalid Confed
info in AS4_PATH (@byte 43) - entire AS4_PATH not ignored
Invalid segment types (ignore the AS4_ PATH)
SYSLOG: Sep 9 19:02:03:<11>mu2, BGP: From Peer 192.168.1.1 received incorrect Seq
type/len in AS4_PATH (@byte 41) - entire AS4_PATH ignored
More than one AS4_PATH (Use the first one and ignore the others)
SYSLOG: Sep 9 19:02:03:<11>mu2, BGP: From Peer 192.168.1.1 received multiple AS4_PATH
attributes - used first AS4_PATH attribute only
Configuring route flap dampening
A route flap is a change in the state of a route, from up to down or down to up. A route state change
causes changes in the route tables of the devices that support the route. Frequent route state changes
can cause Internet instability and add processing overhead to the devices that support the route.
Route flap dampening helps reduce the impact of route flap by changing the way a BGP4 device
responds to route state changes. When route flap dampening is configured, the device suppresses
unstable routes until the number of route state changes drops enough to meet an acceptable degree of
stability. The Brocade implementation of route flap dampening is based on RFC 2439.
Route flap dampening is disabled by default. You can enable the feature globally or on an individual
route basis using route maps.
NOTE
The device applies route flap dampening only to routes learned from EBGP neighbors.
Configuring route flap dampening
FastIron Ethernet Switch Layer 3 Routing Configuration Guide 459
53-1003087-04