This attribute specifies when bumping occurs in the route selection
process. A connection with higher (numerically less) setupPriority
may bump a connection with lower (numerically higher)
setupPriority in order to acquire its bandwidth and be established.
By default, bumping occurs only when it is necessary. That is, a
connection will bump another connection only if there is no other
way for the connection to be established. A connection may be set
to bump in order to use the best available route it may have.