Brocade Communications Systems ICX 7250 series, Configuration Manual

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BGP4 AS4 attribute errors
This section describes the handling of the confederation path segments in the AS4_PATH attribute, and also specifies the error handling
for the new attributes.
To support AS4, the following attributes: AS4_PATH and AS4_Aggregator were specified in RFC 4893. Confederation path segments
in an AS4_PATH are discarded and if there are any other errors such as:
attribute length , flag , confederation segments after AS_SEQ/
AS_SET, Invalid segment types and More than one AS4_PATH in these new attributes, the attribute is discarded and the error is logged.
Error logs
The device generates a log when it encounters attribute errors in AS4_PATH and AS4_AGGREGATOR.
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.
BGP4 AS4 attribute errors
Brocade FastIron Layer 3 Routing Configuration Guide
344 53-1003903-04