diff --git a/tools/testing/selftests/net/packetdrill/accecn/close/close-local-close-then-remote-fin.pkt b/tools/testing/selftests/net/packetdrill/accecn/close/close-local-close-then-remote-fin.pkt
new file mode 100644
index 000000000000..ec7d5f541350
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/close/close-local-close-then-remote-fin.pkt
@@ -0,0 +1,25 @@
+// Test basic connection teardown where local process closes first:
+// the local process calls close() first, so we send a FIN, and receive an ACK.
+// Then we receive a FIN and ACK it.
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +.01...0.011 connect(3, ..., ...) = 0
+ +0 > [noecn] SEWA 0:0(0) <...>
+ +0 < [ect1] SW. 0:0(0) ack 1 win 32768 <mss 1000,nop,wscale 6,nop,nop,sackOK>
+ +0 > [ect0] EW. 1:1(0) ack 1
+
+ +0 write(3, ..., 1000) = 1000
+ +0 > [ect0] P5. 1:1001(1000) ack 1
+ +0 < [ect0] .5 1:1(0) ack 1001 win 257
+
+ +0 close(3) = 0
+ +0 > [ect0] F5. 1001:1001(0) ack 1
+ +0 < [ect0] .5 1:1(0) ack 1002 win 257
+
+ +0 < [ect0] F5. 1:1(0) ack 1002 win 257
+ +0 > [ect0] . 1002:1002(0) ack 2
diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/3rd-ack-lost-data-ce.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/3rd-ack-lost-data-ce.pkt
new file mode 100644
index 000000000000..a043748c0c70
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/3rd-ack-lost-data-ce.pkt
@@ -0,0 +1,22 @@
+// 3rd ACK lost, CE for the first data segment
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
++0.05 < SEWA 0:0(0) win 32767 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+// 3rd ACK lost
++0.05 < [ce] EAP. 1:1001(1000) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] WA. 1:1(0) ack 1001 <ECN e1b 1 ceb 1000 e0b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.05 < [ce] EAP. 1001:2001(1000) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.001 > [ect0] EWA. 1:1(0) ack 2001 <ECN e1b 1 ceb 2000 e0b 1 ,nop>diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-2ndlargeack.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-2ndlargeack.pkt
new file mode 100644
index 000000000000..63c42dab51aa
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-2ndlargeack.pkt
@@ -0,0 +1,25 @@
+// Test a large ACK (> ACE field max)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 14600) = 14600
++.002 > [ect0] P.5 1:14601(14600) ack 1
++0.05 < [ect0] .5 1:1(0) ack 1461 win 264
++0.05 < [ect0] .5 1:1(0) ack 14601 win 264
+
++0.01 %{ assert tcpi_delivered_ce == 8, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-falseoverflow-detect.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-falseoverflow-detect.pkt
new file mode 100644
index 000000000000..8d050d8c1949
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-falseoverflow-detect.pkt
@@ -0,0 +1,31 @@
+// Test false overflow detection with option used to rule out overflow
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
+// Stop sending option to allow easier testing
++0 `sysctl -q net.ipv4.tcp_ecn_option=0`
+
++0.002 write(4, ..., 14600) = 14600
++.002 > [ect0] P.5 1:14601(14600) ack 1
+
++0.05 < [ect0] .5 1:1(0) ack 1460 win 264 <ECN e0b 1461 ceb 0 e1b 1,nop>
++0.05 < [ect0] .5 1:1(0) ack 14601 win 264 <ECN e0b 14601 ceb 0 e1b 1,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 0, tcpi_delivered_ce
+assert tcpi_delivered_e0_bytes == 14600, tcpi_delivered_e0_bytes
+}%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-largeack.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-largeack.pkt
new file mode 100644
index 000000000000..ae6db89c36b2
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-largeack.pkt
@@ -0,0 +1,24 @@
+// Test a large ACK (> ACE field max)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 14600) = 14600
++.002 > [ect0] P.5 1:14601(14600) ack 1
++0.05 < [ect0] .5 1:1(0) ack 14601 win 264
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-largeack2.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-largeack2.pkt
new file mode 100644
index 000000000000..71e27dbc9491
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-largeack2.pkt
@@ -0,0 +1,25 @@
+// Test a large ACK (> ACE field max)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 14600) = 14600
++.002 > [ect0] P.5 1:14601(14600) ack 1
+ // Fake CE
++0.05 < [ect0] .6 1:1(0) ack 14601 win 264
+
++0.01 %{ assert tcpi_delivered_ce == 1, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-maxack.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-maxack.pkt
new file mode 100644
index 000000000000..93a64e5bf5c4
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-maxack.pkt
@@ -0,0 +1,25 @@
+// Test a large ACK (at ACE field max delta)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 14600) = 14600
++.002 > [ect0] P.5 1:14601(14600) ack 1
+ // Fake CE
++0.05 < [ect0] .4 1:1(0) ack 14601 win 264
+
++0.01 %{ assert tcpi_delivered_ce == 7, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-updates.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-updates.pkt
new file mode 100644
index 000000000000..2803df569010
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/delivered-updates.pkt
@@ -0,0 +1,70 @@
+// Test basic AccECN CEP/CEB/E0B/E1B functionality & CEP wrapping
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{
+assert tcpi_delivered_ce == 0, tcpi_delivered_ce
+assert tcpi_delivered_ce_bytes == 0, tcpi_delivered_ce_bytes
+}%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+ // Fake CE
++0.05 < [ect0] WA. 1:1(0) ack 1001 win 264 <ECN e0b 1 ceb 1000 e1b 1,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 1, tcpi_delivered_ce
+assert tcpi_delivered_ce_bytes == 1000, tcpi_delivered_ce_bytes
+}%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1001:2001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+ // Fake ect0
++0.05 < [ect0] WA. 1:1(0) ack 2001 win 264 <ECN e0b 1001 ceb 1000 e1b 1,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 1, tcpi_delivered_ce
+assert tcpi_delivered_e0_bytes == 1000, tcpi_delivered_e0_bytes
+}%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 2001:3001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+ // Fake ce
++0.05 < [ect0] EWA. 1:1(0) ack 3001 win 264 <ECN e0b 1001 ceb 2000 e1b 1,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 2, tcpi_delivered_ce
+assert tcpi_delivered_ce_bytes == 2000, tcpi_delivered_ce_bytes
+}%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 3001:4001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+ // Fake ect1
++0.05 < [ect0] EWA. 1:1(0) ack 4001 win 264 <ECN e0b 1001 ceb 2000 e1b 1001,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 2, tcpi_delivered_ce
+assert tcpi_delivered_e1_bytes == 1000, tcpi_delivered_e1_bytes
+}%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 4001:5001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+ // Fake ce
++0.05 < [ect0] . 1:1(0) ack 5001 win 264 <ECN e0b 1001 ceb 3000 e1b 1001,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 3, tcpi_delivered_ce
+assert tcpi_delivered_ce_bytes == 3000, tcpi_delivered_ce_bytes
+}%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/ecn-field-updates-opt.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/ecn-field-updates-opt.pkt
new file mode 100644
index 000000000000..a7d5eae360c2
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/ecn-field-updates-opt.pkt
@@ -0,0 +1,35 @@
+// Test basic AccECN CEP/CEB/E0B/E1B functionality & CEP wrapping
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.05 < [ce] EAP. 1:1001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] WA. 1:1(0) ack 1001 <ECN e1b 1 ceb 1000 e0b 1,nop>
+ +0 read(4, ..., 1000) = 1000
+
++0.05 < [ect0] EAP. 1001:2001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] WA. 1:1(0) ack 2001 <ECN e1b 1 ceb 1000 e0b 1001,nop>
+ +0 read(4, ..., 1000) = 1000
+
++0.05 < [ce] EAP. 2001:3001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] EWA. 1:1(0) ack 3001 <ECN e1b 1 ceb 2000 e0b 1001,nop>
+ +0 read(4, ..., 1000) = 1000
+
++0.05 < [ect1] EAP. 3001:4001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] EWA. 1:1(0) ack 4001 <ECN e1b 1001 ceb 2000 e0b 1001,nop>
+ +0 read(4, ..., 1000) = 1000
+
++0.05 < [ce] EAP. 4001:5001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] . 1:1(0) ack 5001 <ECN e1b 1001 ceb 3000 e0b 1001,nop>
+ +0 read(4, ..., 1000) = 1000
diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/noprogress.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/noprogress.pkt
new file mode 100644
index 000000000000..c1287372b582
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/noprogress.pkt
@@ -0,0 +1,27 @@
+// Test no progress filtering
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+ // Fake CE and claim no progress
++0.05 < [ect0] WA. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 1000 e1b 1,nop>
+
++0.01 %{
+assert tcpi_delivered_ce == 0, tcpi_delivered_ce
+assert tcpi_delivered_ce_bytes == 0, tcpi_delivered_ce_bytes
+}%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/sack-space-grab-with-ts.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/sack-space-grab-with-ts.pkt
new file mode 100644
index 000000000000..087467a729c8
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/sack-space-grab-with-ts.pkt
@@ -0,0 +1,39 @@
+// Test SACK space grab to fit AccECN option
+--tcp_ts_tick_usecs=1000
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,sackOK,TS val 1 ecr 0,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,sackOK,TS val 100 ecr 1,ECN e1b 1 ceb 0 e0b 1,nop,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <nop,nop,TS val 2 ecr 100,ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
+// One SACK block should allow all 3 AccECN fields:
++.01 < [ect1] EAP. 1001:2001(1000) ack 1 win 264 <nop,nop,TS val 3 ecr 100>
++0.002 > [ect0] EA. 1:1(0) ack 1 <nop,nop,TS val 160 ecr 2,ECN e1b 1001 ceb 0 e0b 1,nop,nop,nop,sack 1001:2001>
+
+// Two SACK blocks should fit w/ AccECN if we only need to use 2 AccECN fields: check ect1 arriving.
++.01 < [ect1] EAP. 3001:4001(1000) ack 1 win 264 <nop,nop,TS val 4 ecr 100>
++0.002 > [ect0] EA. 1:1(0) ack 1 <nop,nop,TS val 172 ecr 2,ECN e1b 2001 ceb 0,nop,nop,sack 3001:4001 1001:2001>
+
+// Two SACK blocks should fit w/ AccECN if we only need to use 2 AccECN fields: check CE arriving.
++.01 < [ce] EAP. 5001:6001(1000) ack 1 win 264 <nop,nop,TS val 5 ecr 100>
++0.002 > [ect0] WA. 1:1(0) ack 1 <nop,nop,TS val 184 ecr 2,ECN e1b 2001 ceb 1000,nop,nop,sack 5001:6001 3001:4001>
+
+// Check that DSACK works, using 2 SACK blocks in total, if we only need to use 2 AccECN fields: check ect1 arriving.
++.01 < [ect1] EAP. 5001:6001(1000) ack 1 win 264 <nop,nop,TS val 5 ecr 100>
++0.002 > [ect0] WA. 1:1(0) ack 1 <nop,nop,TS val 196 ecr 2,ECN e1b 3001 ceb 1000,nop,nop,sack 5001:6001 5001:6001>
+
+// Check the case where the AccECN option doesn't fit, because sending ect0
+// with order 1 would rquire 3 AccECN fields,
+// and TS (12 bytes) + 2 SACK blocks (20 bytes) + 3 AccECN fields (2 + 3*3 bytes) > 40 bytes.
+// That's OK; Linux TCP AccECN is optimized for the ECT1 case, not ECT0.
++.01 < [ect0] EAP. 6001:7001(1000) ack 1 win 264 <nop,nop,TS val 5 ecr 100>
++0.002 > [ect0] WA. 1:1(0) ack 1 <nop,nop,TS val 204 ecr 2,nop,nop,sack 5001:7001 3001:4001 1001:2001>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/sack-space-grab.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/sack-space-grab.pkt
new file mode 100644
index 000000000000..9ec1f1353a35
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/sack-space-grab.pkt
@@ -0,0 +1,28 @@
+// Test SACK space grab to fit AccECN option
+--tcp_ts_tick_usecs=1000
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++.01 < [ect1] EAP. 1001:2001(1000) ack 1 win 264
++0.002 > [ect0] EA. 1:1(0) ack 1 <ECN e1b 1001 ceb 0 e0b 1,nop,nop,nop,sack 1001:2001>
++.01 < [ect0] EAP. 3001:4001(1000) ack 1 win 264
++0.002 > [ect0] EA. 1:1(0) ack 1 <ECN e1b 1001 ceb 0 e0b 1001,nop,nop,nop,sack 3001:4001 1001:2001>
++.01 < [ce] EAP. 5001:6001(1000) ack 1 win 264
++0.002 > [ect0] WA. 1:1(0) ack 1 <ECN e1b 1001 ceb 1000 e0b 1001,nop,nop,nop,sack 5001:6001 3001:4001 1001:2001>
+// DSACK works?
++.01 < [ect0] EAP. 5001:6001(1000) ack 1 win 264
++0.002 > [ect0] WA. 1:1(0) ack 1 <ECN e1b 1001 ceb 1000 e0b 2001,nop,nop,nop,sack 5001:6001 5001:6001 3001:4001>
++.01 < [ect1] EAP. 6001:7001(1000) ack 1 win 264
++0.002 > [ect0] WA. 1:1(0) ack 1 <ECN e1b 2001 ceb 1000 e0b 2001,nop,nop,nop,sack 5001:7001 3001:4001 1001:2001>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/tsnoprogress.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/tsnoprogress.pkt
new file mode 100644
index 000000000000..2f748f42154d
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/tsnoprogress.pkt
@@ -0,0 +1,26 @@
+// Test TS progress filtering
+--tcp_ts_tick_usecs=1000
+--tolerance_usecs=7000
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,sackOK,TS val 1 ecr 0,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,sackOK,TS val 10 ecr 1,ECN e1b 1 ceb 0 e0b 1,nop,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <nop,nop,TS val 2 ecr 10>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <nop,nop,TS val 83 ecr 2>
+ // Fake CE and claim no progress
++0.05 < [ect0] WA. 1:1(0) ack 1 win 264 <nop,nop,TS val 2 ecr 83>
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/counters/tsprogress.pkt b/tools/testing/selftests/net/packetdrill/accecn/counters/tsprogress.pkt
new file mode 100644
index 000000000000..f8c3d9862d16
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/counters/tsprogress.pkt
@@ -0,0 +1,25 @@
+// Test TS progress filtering
+--tcp_ts_tick_usecs=1000
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,sackOK,TS val 1 ecr 0,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,sackOK,TS val 10 ecr 1,ECN e1b 1 ceb 0 e0b 1,nop,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 264 <nop,nop,TS val 2 ecr 10>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <nop,nop,TS val 83 ecr 2>
+ // Fake CE and claim no progress
++0.05 < [ect0] WA. 1:1(0) ack 1 win 264 <nop,nop,TS val 3 ecr 83>
+
++0.01 %{ assert tcpi_delivered_ce == 1, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/acc_ecn_disabled.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/acc_ecn_disabled.pkt
new file mode 100644
index 000000000000..d3a6a0ff6e09
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/acc_ecn_disabled.pkt
@@ -0,0 +1,14 @@
+// Test that when accurate ECN is disabled,
+// client uses RFC3168 ECN for SYN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=1
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEW 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] S. 0:0(0) ack 1 win 32767 <mss 1460,sackOK,nop,nop,nop,wscale 8>
++.002 > [noecn] . 1:1(0) ack 1
+
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/accecn-to-rfc3168.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/accecn-to-rfc3168.pkt
new file mode 100644
index 000000000000..c26262934e37
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/accecn-to-rfc3168.pkt
@@ -0,0 +1,18 @@
+// Test AccECN -> RFC3168 fallback when sysctl asks for RFC3168 ECN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=1
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < . 1:1(0) ack 1 win 320
++.002 accept(3, ..., ...) = 4
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] P. 1:1001(1000) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/client_accecn_options_drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/client_accecn_options_drop.pkt
new file mode 100644
index 000000000000..5a1a2d151277
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/client_accecn_options_drop.pkt
@@ -0,0 +1,34 @@
+// Client negotiates AccECN and starts sending
+// AccECN option in last ACK and data segments
+// Middlebox drops AccECN option and client
+// reverts to ACE flags only
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+sysctl -q net.ipv4.tcp_ecn_option_beacon=1
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.05 < [ect0] EAP. 1:1001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] EA. 1:1(0) ack 1001 <ECN e1b 1 ceb 0 e0b 1001,nop>
+ +0 read(4, ..., 1000) = 1000
+
++0.05 < [ect0] EAP. 1:1001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] EA. 1:1(0) ack 1001 <ECN e1b 1 ceb 0 e0b 2001,nop,nop,nop,sack 1:1001>
+
++0.05 < [ect0] EAP. 1:1001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] EA. 1:1(0) ack 1001 <nop,nop,sack 1:1001>
+
++0.05 < [ect0] EAP. 1001:2001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] EA. 1:1(0) ack 2001
+ +0 read(4, ..., 1000) = 1000
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/client_accecn_options_lost.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/client_accecn_options_lost.pkt
new file mode 100644
index 000000000000..6ce9042e11c2
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/client_accecn_options_lost.pkt
@@ -0,0 +1,38 @@
+// Client negotiates AccECN and starts sending
+// AccECN option in last ACK and data segments
+// Middlebox accepts AccECN option but some packets
+// are lost due to congestion. Client should
+// continue to send AccECN option
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [ect0] SW. 0:0(0) ack 1 win 32767 <mss 1024,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] A. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
+// Send
++0.01 write(4, ..., 3000) = 3000
++.002 > [ect0] .5 1:1013(1012) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++.002 > [ect0] P.5 1013:2025(1012) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++.002 > [ect0] P.5 2025:3001(976) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
+// First two segments were lost due to congestion as SACK was
+// received acknowledging 3rd segment
++0.1 < [ect0] .5 1:1(0) ack 1 win 264 <ECN e1b 1 ceb 0 e0b 977,nop,nop,nop,sack 2025:3001>
+
+// Since data with option was SACKed, we can
+// continue to use AccECN option for the rest of
+// the connection. This one is a rexmt
++.02~+0.5 > [ect0] .5 1:1013(1012) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++0.1 < [ect0] .5 1:1(0) ack 3001 win 264 <ECN e1b 1 ceb 0 e0b 3000,nop>
+
+// Send new data, it should contain AccECN option
++0.01 write(4, ..., 2000) = 2000
++.002 > [ect0] .5 3001:4013(1012) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++.002 > [ect0] P.5 4013:5001(988) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/ecn3.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/ecn3.pkt
new file mode 100644
index 000000000000..3a6f5c5a02ce
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/ecn3.pkt
@@ -0,0 +1,12 @@
+// Test that tcp_ecn=4 uses RFC3168 ECN for SYN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=4
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.05 connect(4, ..., ...) = 0
+
++.002 > SEW 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < S. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > . 1:1(0) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/ipflags-drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/ipflags-drop.pkt
new file mode 100644
index 000000000000..2f9de0f71fe9
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/ipflags-drop.pkt
@@ -0,0 +1,14 @@
+// Test IP flags drop
+--tolerance_usecs=50000
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 1.1 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++.02 ~ +1.1 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < S. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] . 1:1(0) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/listen-opt-drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/listen-opt-drop.pkt
new file mode 100644
index 000000000000..38273576eced
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/listen-opt-drop.pkt
@@ -0,0 +1,16 @@
+// SYN/ACK option drop test
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.02 ~+2 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.02 ~+5 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.02 ~+8 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/multiple_syn_ack_drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/multiple_syn_ack_drop.pkt
new file mode 100644
index 000000000000..acb19cb323a5
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/multiple_syn_ack_drop.pkt
@@ -0,0 +1,28 @@
+// Test that SYN-ACK with ACE flags and without
+// ACE flags got dropped. Although we disable ECN,
+// we shouldn't consider this as blackholed as
+// these are dropped due to congestion
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0 bind(3, ..., ...) = 0
++0 listen(3, 1) = 0
+
++0 < [noecn] SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+
+// Retransmit SYN-ACK without option
++1~+1.1 > [noecn] SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// SYN-ACK maybe getting blackholed, disable ECN
++2~+2.2 > [noecn] S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++4~+4.4 > [noecn] S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// Received an ACK after sending 3rd retransmission, not a blackhole
++0.1 < [noecn] . 1:1(0) ack 1 win 320
++.002 accept(3, ..., ...) = 4
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/multiple_syn_drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/multiple_syn_drop.pkt
new file mode 100644
index 000000000000..2fe03d1c83a2
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/multiple_syn_drop.pkt
@@ -0,0 +1,18 @@
+// Test that SYN with ACE flags and without
+// ACE flags got dropped. Although we disable
+// ECN, we shouldn't consider this as blackholed
+// as these are dropped due to congestion
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 3.1 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++.02~+1.1 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++.02~+1.1 > [noecn] S 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++.02~+1.1 > [noecn] S 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.1 < [noecn] S. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0~+0.01 > [noecn] . 1:1(0) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/negotiation-bleach.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/negotiation-bleach.pkt
new file mode 100644
index 000000000000..9435f8c4f03f
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/negotiation-bleach.pkt
@@ -0,0 +1,23 @@
+// Test AccECN flags bleach
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] . 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [noecn] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++0.05 < [ect0] EAP. 1:1(0) ack 1001 win 320
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/rfc3168-to-fallback.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/rfc3168-to-fallback.pkt
new file mode 100644
index 000000000000..51c3559de6e1
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/rfc3168-to-fallback.pkt
@@ -0,0 +1,18 @@
+// Test RFC3168 fallback when sysctl asks for AccECN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEW 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < . 1:1(0) ack 1 win 320
++.002 accept(3, ..., ...) = 4
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] P. 1:1001(1000) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/rfc3168-to-rfc3168.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/rfc3168-to-rfc3168.pkt
new file mode 100644
index 000000000000..905c62e408df
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/rfc3168-to-rfc3168.pkt
@@ -0,0 +1,18 @@
+// Test RFC3168 ECN when sysctl asks for RFC3168 ECN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=1
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEW 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < . 1:1(0) ack 1 win 320
++.002 accept(3, ..., ...) = 4
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] P. 1:1001(1000) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ace_flags_acked_after_retransmit.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ace_flags_acked_after_retransmit.pkt
new file mode 100644
index 000000000000..9eaa8db924a9
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ace_flags_acked_after_retransmit.pkt
@@ -0,0 +1,18 @@
+// Test that SYN with ACE flags was Acked
+// after 2nd retransmission. In this case,
+// since we got SYN-ACK that supports Accurate
+// ECN, we consider this as successful negotiation
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 2.1 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++1~+1.1 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++1~+1.1 > [noecn] S 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
+
++0.1 < [noecn] SW. 0:0(0) ack 1 win 32767 <mss 1016,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0~+0.01 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ace_flags_drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ace_flags_drop.pkt
new file mode 100644
index 000000000000..b9ddf0426c3b
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ace_flags_drop.pkt
@@ -0,0 +1,16 @@
+// Test that SYN with ACE flags got dropped
+// We retry one more time with ACE and then
+// fallback to disabled ECN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 2.1 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++1~+1.1 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++1~+1.1 > [noecn] S 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.1 < [noecn] S. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0~+0.01 > [noecn] . 1:1(0) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ack_ace_flags_acked_after_retransmit.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ack_ace_flags_acked_after_retransmit.pkt
new file mode 100644
index 000000000000..bf66a2dcd0d5
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ack_ace_flags_acked_after_retransmit.pkt
@@ -0,0 +1,27 @@
+// Test that SYN-ACK with ACE flags was Acked
+// after 2nd retransmission. In this case,
+// since we got the last ACK that supports Accurate
+// ECN, we consider this as successful negotiation
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0 bind(3, ..., ...) = 0
++0 listen(3, 1) = 0
+
++0 < [noecn] SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+
+// Retransmit SYN-ACK without option
++1~+1.1 > [noecn] SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// SYN-ACK maybe getting blackholed, disable ECN
++2~+2.2 > [noecn] S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// Received an ACK with ACE flags, state should be set to negotiation succeeded
++0.1 < [noecn] W. 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
diff --git a/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ack_ace_flags_drop.pkt b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ack_ace_flags_drop.pkt
new file mode 100644
index 000000000000..a05ba4d190a8
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/fallback/syn_ack_ace_flags_drop.pkt
@@ -0,0 +1,27 @@
+// Test that SYN-ACK with ACE flags got dropped
+// We retry one more time with ACE and then
+// fallback to disabled ECN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0 bind(3, ..., ...) = 0
++0 listen(3, 1) = 0
+
++0 < [noecn] SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+
+// Retransmit SYN-ACK without option
++1~+1.1 > [noecn] SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// SYN-ACK maybe getting blackholed, disable ECN
++2~+2.2 > [noecn] S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// Received an ACK with no ACE flags, state should be set to blackholed
++0.1 < [noecn] . 1:1(0) ack 1 win 320
++0 accept(3, ..., ...) = 4
+
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/3rd-ack-after-synack-rxmt.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/3rd-ack-after-synack-rxmt.pkt
new file mode 100644
index 000000000000..ce50bee20db4
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/3rd-ack-after-synack-rxmt.pkt
@@ -0,0 +1,19 @@
+// Test 3rd ACK flags when SYN-ACK is rexmitted
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.1 < [ect0] S. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// Our code currently sends a challenge ACK
+// when it receives a SYN in ESTABLISHED state
+// based on the latest SYN
++.002 > [ect0] A. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/3rd-dups.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/3rd-dups.pkt
new file mode 100644
index 000000000000..4399d904b634
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/3rd-dups.pkt
@@ -0,0 +1,26 @@
+// Test SYN/ACK rexmit triggered 3rd ACK duplicate + CE on first data seg
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+
+// SYN/ACK rexmitted => two 3rd ACKs in-flight
++1.0~+1.1 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+// Delivered 1st 3rd ACK
++0.05 < [ect0] W. 1:1(0) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
+// Duplicate 3rd ACK delivered
++1.05 < [ect0] W. 1:1(0) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
+
++0.05 < [ce] EAP. 1:1001(1000) ack 1 win 257 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] WA. 1:1(0) ack 1001 <ECN e1b 1 ceb 1000 e0b 1,nop>
+ +0 read(4, ..., 1000) = 1000
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/accecn_then_notecn_syn.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/accecn_then_notecn_syn.pkt
new file mode 100644
index 000000000000..7da7f7601ca2
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/accecn_then_notecn_syn.pkt
@@ -0,0 +1,28 @@
+// Test that SYN-ACK with ACE flags and without
+// ACE flags got dropped. Although we disable ECN,
+// we shouldn't consider this as blackholed as
+// these are dropped due to congestion
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0 bind(3, ..., ...) = 0
++0 listen(3, 1) = 0
+
++0 < [ect0] SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] SA. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+
+// Retransmit SYN
++0.1 < [noecn] S 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
++0.1 < [noecn] W. 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
+// Write with AccECN option but with ip-noecn since we received one SYN with ACE=0
++0.01 write(4, ..., 100) = 100
++.002 > [noecn] P5. 1:101(100) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/clientside-disabled.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/clientside-disabled.pkt
new file mode 100644
index 000000000000..e1fa77c18a72
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/clientside-disabled.pkt
@@ -0,0 +1,12 @@
+// AccECN sysctl server-side only, no ECN/AccECN
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=5
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > S 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < S. 0:0(0) ack 1 win 32767 <mss 1460,sackOK,nop,nop,nop,wscale 8>
++.002 > . 1:1(0) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-connect.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-connect.pkt
new file mode 100644
index 000000000000..a8eb14435712
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-connect.pkt
@@ -0,0 +1,23 @@
+// Test basic AccECN negotiation
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++.05 < [ect0] EAP. 1:1(0) ack 1001 win 256 <ECN e0b 1001 ceb 0 e1b 0,nop>
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1001:2001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-listen.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-listen.pkt
new file mode 100644
index 000000000000..60d56208cb1d
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-listen.pkt
@@ -0,0 +1,26 @@
+// Test basic AccECN negotiation
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++0.05 < [ect0] EAP. 1:1(0) ack 1001 win 320
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1001:2001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-noopt-connect.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-noopt-connect.pkt
new file mode 100644
index 000000000000..7c5f1d6ba770
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-noopt-connect.pkt
@@ -0,0 +1,23 @@
+// Test basic AccECN negotiation without option
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < SW. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1
++.05 < [ect0] EAP. 1:1(0) ack 1001 win 256
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1001:2001(1000) ack 1
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-optenable.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-optenable.pkt
new file mode 100644
index 000000000000..44ac0f82c13f
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/negotiation-optenable.pkt
@@ -0,0 +1,23 @@
+// Test basic AccECN negotiation, late option enable
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < SW. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1
++.05 < [ect0] EAP. 1:1(0) ack 1001 win 256 <ECN e0b 1001 ceb 0 e1b 1,nop>
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1001:2001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/no-ecn-after-acc-ecn.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/no-ecn-after-acc-ecn.pkt
new file mode 100644
index 000000000000..ba37a1799398
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/no-ecn-after-acc-ecn.pkt
@@ -0,0 +1,20 @@
+// Test client behavior on receiving a non ECN SYN-ACK
+// after receiving an AccECN SYN-ACK and moving to
+// ESTABLISHED state
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
+// Receive an AccECN SYN-ACK and move to ESTABLISHED
++0.05 < [noecn] SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
+// Receive a non ECN SYN-ACK and send a challenge ACK with ACE feedback
++0.1 < [noecn] S. 0:0(0) ack 1 win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/noopt.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/noopt.pkt
new file mode 100644
index 000000000000..66985d9a16df
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/noopt.pkt
@@ -0,0 +1,27 @@
+// Test basic AccECN negotiation with option off using sysctl
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1
++0.05 < [ect0] EAP. 1:1(0) ack 1001 win 320
+
++0.01 %{ assert tcpi_delivered_ce == 0, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1001:2001(1000) ack 1diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/notecn_then_accecn_syn.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/notecn_then_accecn_syn.pkt
new file mode 100644
index 000000000000..13cdd041045a
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/notecn_then_accecn_syn.pkt
@@ -0,0 +1,28 @@
+// Test that SYN-ACK with ACE flags and without
+// ACE flags got dropped. Although we disable ECN,
+// we shouldn't consider this as blackholed as
+// these are dropped due to congestion
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0 bind(3, ..., ...) = 0
++0 listen(3, 1) = 0
+
++0 < [noecn] S 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
+// Retransmit SYN
++0.1 < [ect0] SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
+
++0.1 < [noecn] . 1:1(0) ack 1 win 320
++.002 accept(3, ..., ...) = 4
+
+// Write with AccECN option but with ip-noecn since we received one SYN with ACE=0
++0.01 write(4, ..., 100) = 100
++.002 > [noecn] P. 1:101(100) ack 1
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-accecn-disabled1.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-accecn-disabled1.pkt
new file mode 100644
index 000000000000..718d3c540397
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-accecn-disabled1.pkt
@@ -0,0 +1,20 @@
+// Test against classic ECN server
+// Not-ECT on SYN and server sets 1|0|1 (AE is unused for classic ECN)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] SEA. 0:0(0) ack 1 win 32767 <mss 1460,sackOK,TS val 700 ecr 100,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <nop, nop, TS val 200 ecr 700>
+
++0 write(4, ..., 100) = 100
++.002 > [ect0] P.5 1:101(100) ack 1 <nop,nop,TS val 300 ecr 700>
++0 close(4) = 0
+
++.002 > [ect0] F.5 101:101(0) ack 1 <nop,nop,TS val 400 ecr 700>
++0.1 < [noecn] R. 1:1(0) ack 102 win 4242
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-accecn-disabled2.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-accecn-disabled2.pkt
new file mode 100644
index 000000000000..6a0a1096c29f
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-accecn-disabled2.pkt
@@ -0,0 +1,20 @@
+// Test against classic ECN server
+// Not-ECT on SYN and server sets 0|0|1
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] SE. 0:0(0) ack 1 win 32767 <mss 1460,sackOK,TS val 700 ecr 100,nop,wscale 8>
++.002 > [noecn] . 1:1(0) ack 1 <nop, nop, TS val 200 ecr 700>
+
++0 write(4, ..., 100) = 100
++.002 > [ect0] P. 1:101(100) ack 1 <nop,nop,TS val 300 ecr 700>
++0 close(4) = 0
+
++0 > [noecn] F. 101:101(0) ack 1 <...>
++0.1 < R. 1:1(0) ack 102 win 4242
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-broken.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-broken.pkt
new file mode 100644
index 000000000000..145a612f6cf4
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-broken.pkt
@@ -0,0 +1,19 @@
+// Test against broken server (1|1|1)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] SEWA. 0:0(0) ack 1 win 32767 <mss 1460,sackOK,TS val 700 ecr 100,nop,wscale 8>
++.002 > [noecn] . 1:1(0) ack 1 <nop, nop, TS val 200 ecr 700>
+
++0 write(4, ..., 100) = 100
++.002 > [noecn] P. 1:101(100) ack 1 <nop,nop,TS val 300 ecr 700>
++0 close(4) = 0
+
++.002 > [noecn] F. 101:101(0) ack 1 <...>
++0.1 < [noecn] R. 1:1(0) ack 102 win 4242
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-ecn-disabled.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-ecn-disabled.pkt
new file mode 100644
index 000000000000..32a6584b43c6
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-ecn-disabled.pkt
@@ -0,0 +1,19 @@
+// Test against Non ECN server (0|0|0)
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] S. 0:0(0) ack 1 win 32767 <mss 1460,sackOK,TS val 700 ecr 100,nop,wscale 8>
++.002 > [noecn] . 1:1(0) ack 1 <nop, nop, TS val 200 ecr 700>
+
++0 write(4, ..., 100) = 100
++.002 > [noecn] P. 1:101(100) ack 1 <nop,nop,TS val 300 ecr 700>
++0 close(4) = 0
+
++.002 > [noecn] F. 101:101(0) ack 1 <nop,nop,TS val 400 ecr 700>
++0.1 < [noecn] R. 1:1(0) ack 102 win 4242
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-only.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-only.pkt
new file mode 100644
index 000000000000..cc141caa8ea1
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/serverside-only.pkt
@@ -0,0 +1,18 @@
+// Test AccECN with sysctl set to server-side only
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=5
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ect0] W. 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/synack-rexmit.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/synack-rexmit.pkt
new file mode 100644
index 000000000000..d19b22c4523a
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/synack-rexmit.pkt
@@ -0,0 +1,15 @@
+// Test 3rd ACK flags when SYN-ACK is rexmitted
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.05 < SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/negotiation/synack-rxmt.pkt b/tools/testing/selftests/net/packetdrill/accecn/negotiation/synack-rxmt.pkt
new file mode 100644
index 000000000000..3acf91c417d6
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/negotiation/synack-rxmt.pkt
@@ -0,0 +1,25 @@
+// Test that we retransmit SYN-ACK with ACE and without
+// AccECN options after
+// SYN-ACK was lost and TCP moved to TCPS_SYN_RECEIVED
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
++0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
++0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
++0 bind(3, ..., ...) = 0
++0 listen(3, 1) = 0
+
++0 < [noecn] SEWA 0:0(0) win 32792 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > [noecn] SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+
+// Retransmit SYN-ACK without option
++1~+1.1 > [noecn] SW. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++0.1 < [noecn] W. 1:1(0) ack 1 win 320 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
+// We try to write with AccECN option
++0.01 write(4, ..., 100) = 100
++.002 > [ect0] P5. 1:101(100) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/2nd-data-as-first-connect.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/2nd-data-as-first-connect.pkt
new file mode 100644
index 000000000000..0571203e086f
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/2nd-data-as-first-connect.pkt
@@ -0,0 +1,30 @@
+// 3rd ACK + 1st data segment lost, 2nd data segments with ce
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [noecn] SW. 0:0(0) ack 1 win 32767 <mss 1016,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
+// 3rd ACK lost
++.002 > [ect0] W. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 write(4, ..., 2000) = 2000
+// 1st data segment lost + 2nd gets CE
++.002 > [ect0] .5 1:1005(1004) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++.000 > [ect0] P.5 1005:2001(996) ack 1 <ECN e1b 1 ceb 0 e0b 1, nop>
++0.05 < [ect0] .6 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 996 e1b 1,nop,nop,nop,sack 1005:2001>
+
++0.01 %{ assert tcpi_delivered_ce == 1, tcpi_delivered_ce }%
+
++0.002~+0.1 > [ect0] .5 1:1005(1004) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++.05 < [ect0] .6 1:1(0) ack 2001 win 264 <ECN e0b 1005 ceb 996 e1b 1,nop>
+
++0.01 write(4, ..., 1000) = 1000
++0~+0.002 > [ect0] P.5 2001:3001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.1 < [ect0] .5 1:1001(1000) ack 3001 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++0~+0.01 > [ect0] .5 3001:3001(0) ack 1001 <ECN e1b 1 ceb 0 e0b 1001,nop>diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/2nd-data-as-first.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/2nd-data-as-first.pkt
new file mode 100644
index 000000000000..512a90c9b8c6
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/2nd-data-as-first.pkt
@@ -0,0 +1,24 @@
+// 3rd ACK + 1st data segment lost, data segments with ce
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
++0.05 < SEWA 0:0(0) win 32767 <mss 1460,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+// 3rd ACK lost
+// 1st data segment lost
++0.05 < [ce] EAP. 1001:2001(1000) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] WA. 1:1(0) ack 1 <ECN e1b 1 ceb 1000 e0b 1,nop,nop,nop,sack 1001:2001>
++.002 accept(3, ..., ...) = 4
+
++0.2 < [ce] EAP. 1:1001(1000) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.001 > [ect0] EWA. 1:1(0) ack 2001 <ECN e1b 1 ceb 2000 e0b 1,nop>
+
++0.05 < [ce] EAP. 2001:3001(1000) ack 1 win 264
++.001 > [ect0] . 1:1(0) ack 3001 <ECN e1b 1 ceb 3000 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/3rd-ack-ce-updates-received_ce.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/3rd-ack-ce-updates-received_ce.pkt
new file mode 100644
index 000000000000..4ca63fd1831b
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/3rd-ack-ce-updates-received_ce.pkt
@@ -0,0 +1,18 @@
+// Third ACK CE increases r.cep
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
++0.05 < SEWA 0:0(0) win 32767 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
++0.05 < [ce] W. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] WAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ce.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ce.pkt
new file mode 100644
index 000000000000..0fdf387aa1ee
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ce.pkt
@@ -0,0 +1,13 @@
+// Test AccECN ECN field reflector in SYNACK
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < [ce] SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SWA. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ect0.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ect0.pkt
new file mode 100644
index 000000000000..951bf9eea7b5
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ect0.pkt
@@ -0,0 +1,13 @@
+// Test AccECN ECN field reflector in SYNACK
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < [ect0] SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SA. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ect1.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ect1.pkt
new file mode 100644
index 000000000000..ff6f3293a774
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/syn-ect1.pkt
@@ -0,0 +1,13 @@
+// Test AccECN ECN field reflector in SYNACK
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
+ +0 < [ect1] SEWA 0:0(0) win 32792 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SEW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ce-updates-delivered-ce.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ce-updates-delivered-ce.pkt
new file mode 100644
index 000000000000..b497ba9c6935
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ce-updates-delivered-ce.pkt
@@ -0,0 +1,22 @@
+// Reflected SYNACK CE mark increases delivered_ce
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_fallback=0
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+ +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+ +0 bind(3, ..., ...) = 0
+ +0 listen(3, 1) = 0
+
++0.05 < SEWA 0:0(0) win 32767 <mss 1050,nop,nop,sackOK,nop,wscale 8>
++.002 > SW. 0:0(0) ack 1 <mss 1460,ECN e1b 1 ceb 0 e0b 1,nop,nop,nop,sackOK,nop,wscale 8>
+// Fake ce for prev, ECT validator must be disabled for this to work
++0.05 < [ect0] WA. 1:1(0) ack 1 win 264 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 accept(3, ..., ...) = 4
+
++0.01 %{ assert tcpi_delivered_ce == 1, tcpi_delivered_ce }%
+
++0.01 write(4, ..., 1000) = 1000
++.002 > [ect0] EAP. 1:1001(1000) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ce.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ce.pkt
new file mode 100644
index 000000000000..53cd0e9473b4
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ce.pkt
@@ -0,0 +1,28 @@
+// Test SYNACK CE & received_ce update
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+sysctl -q net.ipv4.tcp_ecn_option=2
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [ce] SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] WA. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 write(4, ..., 100) = 100
++.002 > [ect0] P.6 1:101(100) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++0.05 < [ect0] P.5 1:101(100) ack 101 win 256 <ECN e0b 101 ceb 0 e1b 1,nop>
++.002 > [ect0] .6 101:101(0) ack 101 <ECN e1b 1 ceb 0 e0b 101,nop>
+
++0.01 write(4, ..., 100) = 100
++.002 > [ect0] P.6 101:201(100) ack 101 <ECN e1b 1 ceb 0 e0b 101,nop>
+
++0.1 < [ect1] P.5 201:301(100) ack 201 win 256 <ECN e0b 101 ceb 0 e1b 1,nop>
++.002 > [ect0] .6 201:201(0) ack 101 <ECN e1b 101 ceb 0 e0b 101,nop,nop,nop,sack 201:301>
+
++0.01 < [ce] .6 401:501(100) ack 201 win 256 <ECN e0b 101 ceb 0 e1b 1,nop>
++.002 > [ect0] .7 201:201(0) ack 101 <ECN e1b 101 ceb 100 e0b 101,nop,nop,nop,sack 401:501 201:301>
+
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ect0.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ect0.pkt
new file mode 100644
index 000000000000..27355e27c55d
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ect0.pkt
@@ -0,0 +1,24 @@
+// Test SYN=0 reflector
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [ect0] SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] A. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 write(4, ..., 100) = 100
++.002 > [ect0] P.5 1:101(100) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++0.05 < [ect0] P.5 1:1(0) ack 101 win 256 <ECN e0b 101 ceb 0 e1b 1,nop>
+
++0.01 < [ect0] P.5 1:101(100) ack 101 win 256 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] .5 101:101(0) ack 101 <ECN e1b 1 ceb 0 e0b 101,nop>
++0 read(4, ..., 100) = 100
+
++0 close(4) = 0
++0 > F.5 101:101(0) ack 101 <...>
++0.1 < R. 101:101(0) ack 102 win 4242
diff --git a/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ect1.pkt b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ect1.pkt
new file mode 100644
index 000000000000..5d8e29143ac5
--- /dev/null
+++ b/tools/testing/selftests/net/packetdrill/accecn/reflector/synack-ect1.pkt
@@ -0,0 +1,24 @@
+// Test SYN=0 reflector
+
+`../../common/defaults.sh
+sysctl -q net.ipv4.tcp_ecn=3
+`
+
+ 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
++.002 ... 0.052 connect(4, ..., ...) = 0
+
++.002 > SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
++0.05 < [ect1] SW. 0:0(0) ack 1 win 32767 <mss 1460,ECN e0b 1 ceb 0 e1b 1,nop,nop,nop,sackOK,nop,wscale 8>
++.002 > [ect0] EW. 1:1(0) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
+
++0.01 write(4, ..., 100) = 100
++.002 > [ect0] P.5 1:101(100) ack 1 <ECN e1b 1 ceb 0 e0b 1,nop>
++0.05 < [ect1] P.5 1:1(0) ack 101 win 256 <ECN e0b 101 ceb 0 e1b 1,nop>
+
++0.01 < [ect1] P.5 1:101(100) ack 101 win 256 <ECN e0b 1 ceb 0 e1b 1,nop>
++.002 > [ect0] .5 101:101(0) ack 101 <ECN e1b 101 ceb 0 e0b 1,nop>
++0 read(4, ..., 100) = 100
+
++0 close(4) = 0
++0 > F5. 101:101(0) ack 101 <...>
++0.1 < R. 101:101(0) ack 102 win 4242
--
2.34.1