Constant DEFAULT_SLOT_SIZE 

pub const DEFAULT_SLOT_SIZE: u32 = 8960;

Default slot payload size in bytes (~8.75 KiB). Covers a standard NDN Data packet (≤8800 bytes on most link types) with a small headroom margin. This is the right default for the majority of NDN traffic: Interests (~60–200 bytes), single-packet Data (~4–8 KiB content), iperf probes, ping, management, etc.

Tools that produce larger Data (chunked file transfers at 64 KiB, 256 KiB, or 1 MiB segments) negotiate a bigger slot via the mtu field of faces/create ControlParameters. ndn-put does this automatically from --chunk-size; ndn-peek accepts --mtu.