Hello! I am thinking about advancing the ipv4/tcp_ecn knob in linux to distinguish between ipv4 and ipv6 transport and enable ecn signaling on outgoing ipv6 connections by default (for me, at least). I am currently doing so with the help of iptables (echo 1 > tcp_ecn and -j ECN --ecn-tcp-remove).
Currently linux does only respond to ecn signaling but does not actively try to signal ecn capabilities by default because of the high(?) fail rate of connections in ipv4 land. I wonder if this situation has improved in ipv6 world because I assume most providers have upgraded their gear in recent times to support this shiny new protocol. Does someone know about recent data if such a change would be reasonable? Btw, has someone looked at RFC5562 - Adding Explicit Congestion Notification (ECN) Capability to TCP's SYN/ACK Packets; experimental? Adam Langley has provided a patch for linux enabling ecn on syn/ack packets some while ago[1]. This seems to be a nice addition but I fear for new problems arising because of buggy routers. Perhaps after the retransmit of the initial syn without the ecn-capable codepoint one could mark this connection as non-ecn compatible in the destination cache to reduce further latencies on follow-up syns (kind of path ecn discovery). Greetings, Hannes [1] https://www.ietf.org/mail-archive/web/tcpm/current/msg03988.html _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
