mtu: per-interface MTU configuration via netcfg

LinkDevice trait gains set_mtu(mtu) with default no-op.
EthernetLink stores mtu in field, clamped to 576-9000 (RFC 791 min/max).

netcfg/ifaces/eth0/mtu becomes rw:
  cat /scheme/netcfg/ifaces/eth0/mtu  →  '1500' (default)
  echo 1400 > .../mtu  →  VPN MTU
  echo 9000 > .../mtu  →  jumbo frames

Clamped to [576, 9000]:
- 576: minimum for IPv4 (RFC 791)
- 9000: standard jumbo frame MTU

Useful for VPNs (MTU 1400 to avoid fragmentation through tunnel overhead),
jumbo frames (MTU 9000 on datacenter networks), and constrained paths.

This commit is contained in:

Red Bear OS

2026-07-08 17:57:16 +03:00

parent c1cfee3bea

commit c015a375b1

3 changed files with 26 additions and 1 deletions

									
										netstack/src/link/mod.rs
									
		+2
		
												View File
												
				@@ -57,6 +57,8 @@ pub trait LinkDevice {

				        1500

				    }

				    fn set_mtu(&mut self, _mtu: usize) {}

				    fn link_state(&self) -> &'static str {

				        "unknown"

				    }