BGP parameters are initially applied on the global level. These parameters are inherited by the group and neighbor (peer) levels. Parameters can be modified and overridden on a level-specific basis. BGP command hierarchy consists of three levels:
global level
group level
neighbor level
Many of the hierarchical BGP commands can be modified on different levels. The most specific value is used. That is, a BGP group-specific command takes precedence over a global BGP command. A neighbor-specific statement takes precedence over a global BGP and group-specific command; for example, if you modify a BGP neighbor-level command default, the new value takes precedence over group- and global- level settings.
Careful planning is essential to implement commands that can affect the behavior of global, group, and neighbor-levels. Because the BGP commands are hierarchical, analyze the values that can disable features on the global or group levels that must be enabled at the neighbor level. For example, if you enable the damping command on the global level but want it disabled only for a specific neighbor (not for all neighbors within the group), you cannot configure a double no command (no no damping) to enable the feature.