**This is an old revision of the document!** ----
====== TCP Tuning ====== By default, Centos used the following TCP parameters: <code> $ sysctl -a net.ipv4.tcp_slow_start_after_idle = 1 net.ipv4.tcp_dma_copybreak = 4096 net.ipv4.tcp_workaround_signed_windows = 0 net.ipv4.tcp_base_mss = 512 net.ipv4.tcp_mtu_probing = 0 net.ipv4.tcp_abc = 0 net.ipv4.tcp_congestion_control = bic net.ipv4.tcp_tso_win_divisor = 3 net.ipv4.tcp_moderate_rcvbuf = 1 net.ipv4.tcp_no_metrics_save = 0 net.ipv4.ipfrag_max_dist = 64 net.ipv4.ipfrag_secret_interval = 600 net.ipv4.tcp_low_latency = 0 net.ipv4.tcp_frto = 0 net.ipv4.tcp_tw_reuse = 0 net.ipv4.icmp_ratemask = 6168 net.ipv4.icmp_ratelimit = 1000 net.ipv4.tcp_adv_win_scale = 2 net.ipv4.tcp_app_win = 31 net.ipv4.tcp_rmem = 4096 87380 4194304 net.ipv4.tcp_wmem = 4096 16384 4194304 net.ipv4.tcp_mem = 196608 262144 393216 net.ipv4.tcp_dsack = 1 net.ipv4.tcp_ecn = 0 net.ipv4.tcp_reordering = 3 net.ipv4.tcp_fack = 1 net.ipv4.tcp_orphan_retries = 0 net.ipv4.tcp_max_syn_backlog = 1024 net.ipv4.tcp_rfc1337 = 0 net.ipv4.tcp_stdurg = 0 net.ipv4.tcp_abort_on_overflow = 0 net.ipv4.tcp_tw_recycle = 0 net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_fin_timeout = 60 net.ipv4.tcp_retries2 = 15 net.ipv4.tcp_retries1 = 3 net.ipv4.tcp_keepalive_intvl = 75 net.ipv4.tcp_keepalive_probes = 9 net.ipv4.tcp_keepalive_time = 7200 net.ipv4.tcp_max_tw_buckets = 180000 net.ipv4.tcp_max_orphans = 65536 net.ipv4.tcp_synack_retries = 5 net.ipv4.tcp_syn_retries = 5 net.ipv4.tcp_retrans_collapse = 1 net.ipv4.tcp_sack = 1 net.ipv4.tcp_window_scaling = 1 net.ipv4.tcp_timestamps = 1 net.core.netdev_budget = 300 net.core.somaxconn = 128 net.core.xfrm_larval_drop = 0 net.core.xfrm_acq_expires = 30 net.core.xfrm_aevent_rseqth = 2 net.core.xfrm_aevent_etime = 10 net.core.optmem_max = 20480 net.core.message_burst = 10 net.core.message_cost = 5 net.core.netdev_max_backlog = 1000 net.core.dev_weight = 64 net.core.rmem_default = 129024 net.core.wmem_default = 129024 net.core.rmem_max = 131071 net.core.wmem_max = 131071 </code>
