Out of curiosity, does anyone know, according to the LTE spec, where in particular the down/up AMBRs are actually being enforced on the network? Is it all taking place at the EPC? Or does the EPC inform the eNB of UE-AMBR and have the eNB take it into account as it schedules things? Or is the UE informed of it when it attaches to the network and it is the UE's responsibility to enforce it in whole (both down/up) or in part (just up)?
When I first dived into DOCSIS, I remember being shocked to learn that the bandwidth constraints were values included in the provisioning file that was fed to the cable modem, and it was in fact up to the modem to enforce the specified throughput limits. I think the explanation I remember hearing is that it is better to have the limit enforcement distributed instead of centralized because at least in the uplink direction, the modem would be free to schedule/queue packets it was transmitting in an intelligent way rather than force the network to throttle things more primitively by simply throwing packets out (which will slow down TCP, but not necessarily contain a barrage of UDP). However, this meant that vulnerabilities in modem firmware could allow for circumvention/abuse by the customer (which is not just academic and has in fact happened). So there are some trade-offs. I am interested to know which way the 3GPP leaned. (And perhaps the scheduling mechanisms that LTE uses make the centralized vs. distributed debate a non-starter anyway.) Thanks, -- Nathan Anderson First Step Internet, LLC nath...@fsr.com _______________________________________________ Telrad mailing list Telrad@wispa.org http://lists.wispa.org/mailman/listinfo/telrad