FIG. 3B schematically illustrates a first example implementation of the congestion notification message 300 shown in FIG. 3A. As can be seen in FIG. 3B, the back-off information 320 may in some embodiments include one or more of the following parameters: back-off rate 321, back-off time 322, and ramp-up time 323. Furthermore, the flow identifier 310 may include a Packet Data Conversion Protocol (PDCP) Flow Identification (FID) 311. In the example implementation shown in FIG. 3B, the Type field defines that this is a PDCP Flow ID notification message. The PDCP Flow-ID field identifies the specific flow using the following flow ID variant: PDCP Flow ID (PDCP-FID). The back-off rate 321 may comprise information about how much a second network node shall back-off. This is typically, but not necessarily, expressed in terms of rate (e.g., bandwidth) and may e.g. be an explicit rate number or described as a percentage back-off from the instantaneously used bandwidth. The back-off time 322 may comprise information about how long the back-off should be performed. This is typically, but not necessarily, expressed in terms of time (e.g., seconds). The ramp-up time 323 may comprises information about how fast the ramp-up should be, e.g., the shortest allowed time (e.g., in seconds) to get back to previous used rate (bandwidth). The back-off rate 321, back-off time 322 and ramp-up time 323 timer parameter values may all vary from 0 (zero), which is a special case, and up to an (in principle) unlimited value, which is also a special case.
