tools/testing/selftests/net/packetdrill/tcp_ecn_ecn-uses-ect0.pkt

Source file repositories/reference/linux-study-clean/tools/testing/selftests/net/packetdrill/tcp_ecn_ecn-uses-ect0.pkt

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/net/packetdrill/tcp_ecn_ecn-uses-ect0.pkt
Extension
.pkt
Size
643 bytes
Lines
22
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

// SPDX-License-Identifier: GPL-2.0
// Test ECN: verify that Linux TCP ECN sending code uses ECT0 (not ECT1).
//
`./defaults.sh
sysctl -q net.ipv4.tcp_ecn=1  # fully enabled
`

// Initialize connection
    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4

// ECN handshake: send EW flags in SYN packet, E flag in SYN-ACK response
+.002 ... 0.004 connect(4, ..., ...) = 0

   +0 > SEW 0:0(0) <mss 1460,sackOK,TS val 100 ecr 0,nop,wscale 8>
+.002 < SE. 0:0(0) ack 1 win 32767 <mss 1000,nop,wscale 6,nop,nop,sackOK>
   +0 > . 1:1(0) ack 1

// Write 1 MSS.
+.002 write(4, ..., 1000) = 1000
// Send 1 MSS with ect0.
   +0 > [ect0] P. 1:1001(1000) ack 1

Annotation

Implementation Notes