Rt updating bgp 0 0 0 0 0
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The community value can be entered as a decimal number or in the AA: NN format.Communities are shown as numeric numbers by default.It is recommended to implement the global configuration command to display BGP communities in the AA: NN format to conform with RFC 1997.Regular expressions can be used for filtering outputs of the A multiplier can be applied upon single- or multiple-character patterns.To apply a multiplier upon a multi-character pattern, enclose the pattern in parenthesis.Many disastrous Internet outages have occurred over the past due to misconfigurations and software bugs in BGP implementations; false updates, de-aggregation, and prefix hijacking in which an AS announces the routes that it does not have would eventually cause blackholing.
Any serious and security-aware ISP should perform some sanity checks upon the BGP routes received from its customer instead of blindly accepting them.
They are mutually exclusive, in which only either one can be applied upon each direction.
The BGP router subcommand filters the routing information to be advertised to a BGP neighbor or peer group based upon the specified prefix list.
An AS path filter list entry matches the AS_PATH attribute pattern using a regular expression along with a permit or deny action.
The EXEC command displays BGP routes that conform to a specified filter list.
When multiple filters (distribute list, prefix list, filter list, route map) are configured for a neighbor, the filters are processed in a specific order as shown in the figure above.