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# 2021-01-20 Transport Layer Protocol TCP

- 参加者: hayakawa, kawakami, taguchi

### 輻輳制御がかっこいい話
- https://www.youtube.com/watch?v=MAni0_lN7zE
- https://www.semanticscholar.org/paper/Making-Linux-TCP-Fast-Cheng-Cardwell/eeec259a40f8c7caefc065cc7cbb96ff0f496f89

### TCPのかっこいい話
- https://tools.ietf.org/html/draft-ietf-tcpm-rack-15
- Urgent/Push: https://packetlife.net/blog/2011/mar/2/tcp-flags-psh-and-urg/

### 気になるsysctl
- /proc/sys/net/ipv4/tcp_base_mss
- /proc/sys/net/ipv4/tcp_challenge_ack_limit
- sack
- /proc/sys/net/ipv4/tcp_comp_sack_delay_ns
- /proc/sys/net/ipv4/tcp_comp_sack_nr
- /proc/sys/net/ipv4/tcp_dsack
- dsackとは?
- Duplicated SACK
- /proc/sys/net/ipv4/tcp_early_demux
- Early demuxとは？
- /proc/sys/net/ipv4/tcp_early_retrans
- Early retransとは？
- ECN
- ECNとは？
- /proc/sys/net/ipv4/tcp_ecn
- /proc/sys/net/ipv4/tcp_ecn_fallback
- DCTCP
- /proc/sys/net/ipv4/tcp_fack
- FACKとは？
- Fast ACK?
- TCP Fast Open
- /proc/sys/net/ipv4/tcp_fastopen
- /proc/sys/net/ipv4/tcp_fastopen_blackhole_timeout_sec
- /proc/sys/net/ipv4/tcp_fastopen_key
- /proc/sys/net/ipv4/tcp_fin_timeout
- time-wait関係?
- /proc/sys/net/ipv4/tcp_frto
- FRTOとは？
- Forward Retransmit Time Out
- /proc/sys/net/ipv4/tcp_fwmark_accept
- SYNパケットにmarkつけておくとacceptソケットから出てくるパケットにそのmarkがつくようになる
- ipftraceに便利そう
- /proc/sys/net/ipv4/tcp_invalid_ratelimit
- ACK loop対策？
- Keepalive
- Keepaliveみんな使ってるの？
- /proc/sys/net/ipv4/tcp_keepalive_intvl
- /proc/sys/net/ipv4/tcp_keepalive_probes
- /proc/sys/net/ipv4/tcp_keepalive_time
- TCP Small Queue
- /proc/sys/net/ipv4/tcp_limit_output_bytes
- SNDBUF autotuning
- /proc/sys/net/ipv4/tcp_max_orphans
- socketがorphanになる状況とは？
- TIME_WAITは？
- /proc/sys/net/ipv4/tcp_max_reordering
- /proc/sys/net/ipv4/tcp_reordering
- reordering levelとは?
- /proc/sys/net/ipv4/tcp_max_syn_backlog
- よく使う
- /proc/sys/net/ipv4/tcp_max_tw_buckets
- orphanとは違う？
- /proc/sys/net/ipv4/tcp_mem
- Memory pressure modeとは？
- /proc/sys/net/ipv4/tcp_min_rtt_wlen
- /proc/sys/net/ipv4/tcp_moderate_rcvbuf
- buffer auto tuning
- /proc/sys/net/ipv4/tcp_rmem
- /proc/sys/net/ipv4/tcp_mtu_probing
- PLPMTUD?
- /proc/sys/net/ipv4/tcp_no_metrics_save
- route cacheにmetricsを仕込める?
- /proc/sys/net/ipv4/tcp_no_ssthresh_metrics_save
- route cacheに仕込める系
- /proc/sys/net/ipv4/tcp_notsent_lowat
- pollとかに関係あるっぽい
- /proc/sys/net/ipv4/tcp_orphan_retries
- Orphan socketとは？
- Pacing
- /proc/sys/net/ipv4/tcp_pacing_ca_ratio
- /proc/sys/net/ipv4/tcp_pacing_ss_ratio
- PLPMTUD
- /proc/sys/net/ipv4/tcp_probe_interval
- /proc/sys/net/ipv4/tcp_probe_threshold
- Loss Recovery
- /proc/sys/net/ipv4/tcp_recovery
- /proc/sys/net/ipv4/tcp_retrans_collapse
- そんなひどいPrinterある？
- 再送制御
- /proc/sys/net/ipv4/tcp_retries1
- /proc/sys/net/ipv4/tcp_retries2
- RFC1337
- /proc/sys/net/ipv4/tcp_rfc1337
- TIME-WAIT Assassination Hazards
- https://tools.ietf.org/html/rfc1337
- RC2861
- /proc/sys/net/ipv4/tcp_slow_start_after_idle
- https://tools.ietf.org/html/rfc2861
- Urgent
- /proc/sys/net/ipv4/tcp_stdurg
- /proc/sys/net/ipv4/tcp_synack_retries
- SYNCookie
- /proc/sys/net/ipv4/tcp_syncookies
- /proc/sys/net/ipv4/tcp_thin_linear_timeouts
- Thin streamとは？
- Documentation/networking/tcp-thin.txt
- /proc/sys/net/ipv4/tcp_timestamps
- /proc/sys/net/ipv4/tcp_tso_win_divisor
- 輻輳window?ふつうのwindowではなく？
- /proc/sys/net/ipv4/tcp_tx_skb_cache
- https://www.mail-archive.com/[e-mail]/msg302564.html

### 調べたいやつ

#### 基本
- 3WHSの挙動を調べる
- Reno?

#### 発展
- Fast Open
- Orphan
- Pacing
- ECN