For maintaining a certain quality of service for a certain type of data traffic, the data traffic may be directed to a corresponding bearer established with respect to a user equipment. By sending probe packets on the bearer and/or on a further bearer and receiving a response packets returned in response to the probe packets, a parameter corresponding to a time period between sending a probe packet and receiving the corresponding response packet can be measured. On the basis of the measured parameter, a bearer control procedure with respect to the user equipment is initiated. This bearer control procedure may for example include directing data packets of selected data traffic from one bearer to another bearer, modification of at least one quality of service parameter of a bearer, and/or establishing or releasing a bearer.