Changing HDLC Timers in Remote Systems

Another question related to transport of HDLC (or LAPB) frames over L2TPv3:

HDLC identifies a number of timers that may be used by an HDLC link 
(which is operating in the reliable ABM Mode) to provide reliable data 
transmission, such as the Acknowledgement Timer (T1).

According RFC 4349 (HDLCPWs over L2TPv3), depending on the quality of 
the link between the LCCEs, the HDLC expiration times may need tweaking 
though.

If so, it may need a PSN with excellent QoS or to change HDLC timers in 
HDLC terminales (Remote System for RFC 4349), but the last, changing all 
terminals, is not a viable solution, I think.

Javi