Enabling Internet-Wide Deployment of Explicit Congestion Notification

The Benefits of Using Explicit Congestion Notification (ECN)

“…Cases have been noted where an endpoint sends a packet with a non-zero ECN mark, but the packet is received by the remote endpoint with a zero ECN codepoint [TR15]. This could be a result of a policy that erases or "bleaches" the ECN codepoint values at a network edge (resetting the codepoint to zero).…”

Relaxing Restrictions on Explicit Congestion Notification (ECN) Experimentation

“…A study of the ECN behavior of the top one million web servers using 2014 data [Trammell15] found that after ECN was negotiated, none of the 581,711 IPv4 servers tested were using both ECT codepoints, which would have been a possible sign of ECN nonce usage. Of the 17,028 IPv6 servers tested, four set both ECT(0) and ECT(1) on data packets.…”

Is Explicit Congestion Notification usable with UDP?

“…Trammell et al [14] probed the Alexa top web servers list, finding 56.17% of IPv4 servers tested in August-September 2014 were willing to negotiate ECN, rising to 65.41% of IPv6 servers. They also studied ECN-dependent connectivity, finding 0.42% of servers showed differences in connectivity when ECN was requested for TCP; this is comparable to our results for UDP.…”

“…For example, Trammell at el. [14] conducted active probes of the Alexa Top million web servers list in 2014 and found 56.17% negotiated ECN when requested. Similar studies by Kühlewind et al [6] found 29.48% would negotiate ECN in 2012, while [1] found 17.2% would negotiate ECN.…”

“…The current ECN standard for TCP/IP [10] was published in 2001, and has seen wide implementation, but only moderate use, in part due to concerns about compatibility with firewalls and other middleboxes. Recent work [14] has eased those concerns, and use of ECN is growing. With this growth, we are now starting to see broader interest in using ECN, including use with transport protocols that layer above UDP.…”