Struct KcpConfig 

pub struct KcpConfig {
    pub nodelay: bool,
    pub interval: u32,
    pub resend: i32,
    pub nc: bool,
    pub mtu: u32,
    pub snd_wnd: u32,
    pub rcv_wnd: u32,
    pub stream_mode: bool,
}

KCP protocol configuration parameters.

Controls the behavior of the underlying KCP engine. Use the provided presets (default(), fast(), normal()) or customize individual fields.

Example

use kcp_io::core::KcpConfig;

// Use a preset
let config = KcpConfig::fast();

// Customize from a preset
let config = KcpConfig {
    mtu: 1200,
    snd_wnd: 256,
    rcv_wnd: 256,
    ..KcpConfig::fast()
};

Fields

nodelay: bool

Enable nodelay mode. When true, KCP disables the wait-to-send delay and sends packets as soon as possible, reducing latency.

interval: u32

Internal update interval in milliseconds. Lower values reduce latency but increase CPU usage. Typical range: 10–100 ms.

resend: i32

Fast retransmit trigger count. When an out-of-order ACK is received this many times, KCP immediately retransmits the packet without waiting for a timeout. Set to 0 to disable fast retransmit.

nc: bool

Disable congestion control. When true, KCP ignores the congestion window and sends at full speed (uses nocwnd mode). Useful for low-latency scenarios where bandwidth is not a concern.

mtu: u32

Maximum Transmission Unit in bytes. This is the maximum size of a single KCP output packet (including the 24-byte KCP header). Must account for UDP header overhead (28 bytes for IPv4). Default: 1400.

snd_wnd: u32

Send window size (number of packets). Larger values allow higher throughput but consume more memory. Default: 32.

rcv_wnd: u32

Receive window size (number of packets). Should generally be >= snd_wnd. Larger values allow higher throughput. Default: 128.

stream_mode: bool

Enable stream mode. When true, KCP operates like a byte stream (similar to TCP), merging small packets and splitting large ones. When false (default), KCP preserves message boundaries.

Implementations

impl KcpConfig

pub fn fast() -> Self

Returns a low-latency (fast) configuration preset.

Optimized for minimal latency at the cost of higher bandwidth usage.

• nodelay: true
• interval: 10 ms
• resend: 2 (fast retransmit after 2 out-of-order ACKs)
• nc: true (congestion control disabled)
• mtu: 1400
• snd_wnd: 128, rcv_wnd: 128
• stream_mode: false

pub fn normal() -> Self

Returns a balanced (normal) configuration preset.

Balances latency and bandwidth usage. Good for most use cases.

• nodelay: true
• interval: 40 ms
• resend: 2
• nc: false (congestion control enabled)
• mtu: 1400
• snd_wnd: 64, rcv_wnd: 128
• stream_mode: false

Trait Implementations

impl Clone for KcpConfig

fn clone(&self) -> KcpConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for KcpConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for KcpConfig

fn default() -> Self

Returns a conservative default configuration.

• nodelay: false
• interval: 100 ms
• resend: 0 (no fast retransmit)
• nc: false (congestion control enabled)
• mtu: 1400
• snd_wnd: 32, rcv_wnd: 128
• stream_mode: false