tools/testing/selftests/net/packetdrill/tcp_accecn_client_accecn_options_lost.pkt

Source file repositories/reference/linux-study-clean/tools/testing/selftests/net/packetdrill/tcp_accecn_client_accecn_options_lost.pkt

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/net/packetdrill/tcp_accecn_client_accecn_options_lost.pkt
Extension
.pkt
Size
1569 bytes
Lines
39
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: tools
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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

`./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 ... 0.102 connect(4, ..., ...) = 0

+.002 > [noecn] SEWA 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
+0.1  < [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>

Annotation

Implementation Notes