Is CoAP Congestion Safe?

A huge number of Internet of Things (IoT) devices are expected to be connected to the Internet in the near future. The Constrained Application Protocol (CoAP) has been increasingly deployed for wide-area IoT communication. It is crucial to understand how the specified CoAP congestion control algorithms perform. We seek an answer to this question by performing an extensive evaluation of the existing IETF CoAP Congestion Control proposals. We find that they fail to address congestion properly, particularly in the presence of a bufferbloated bottleneck buffer. We also fix the problem with a few simple modifications and demonstrate their effectiveness.

[1]  Zhen Cao,et al.  CoAP Latency Evaluation , 2016 .

[2]  Godred Fairhurst,et al.  IETF Recommendations Regarding Active Queue Management , 2015, RFC.

[3]  Stephen Farrell,et al.  Low-Power Wide Area Network (LPWAN) Overview , 2018, RFC.

[4]  Carsten Bormann,et al.  The Constrained Application Protocol (CoAP) , 2014, RFC.

[5]  August Betzler,et al.  Congestion control for CoAP cloud services , 2014, Proceedings of the 2014 IEEE Emerging Technology and Factory Automation (ETFA).

[6]  Markku Kojo,et al.  Experimental evaluation of alternative congestion control algorithms for Constrained Application Protocol (CoAP) , 2015, 2015 IEEE 2nd World Forum on Internet of Things (WF-IoT).

[7]  August Betzler,et al.  CoAP congestion control for the internet of things , 2016, IEEE Communications Magazine.

[8]  Vern Paxson,et al.  Computing TCP's Retransmission Timer , 2000, RFC.

[9]  August Betzler,et al.  CoAP Simple Congestion Control/Advanced , 2016 .

[10]  Mahesh Sooriyabandara,et al.  Low Power Wide Area Networks: An Overview , 2016, IEEE Communications Surveys & Tutorials.

[11]  J Gettys,et al.  Bufferbloat: Dark Buffers in the Internet , 2011, IEEE Internet Computing.

[12]  Craig Partridge,et al.  Improving round-trip time estimates in reliable transport protocols , 1991, TOCS.

[13]  John Nagle,et al.  Congestion control in IP/TCP internetworks , 1984, CCRV.

[14]  August Betzler,et al.  CoCoA+: An advanced congestion control mechanism for CoAP , 2015, Ad Hoc Networks.