MTU

wikipedia:Maximum transmission unit (MTU)

• Cisco IOS: show system mtu

Change configuration on Linux:

• ip link set dev eth0 mtu 9000 (Jumbo frames)

• ifconfig -a | grep mtu

ifconfig -a | grep mtu
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9001

• ping -M do -s 9000 <some_ip_address>

Select Path MTU Discovery strategy. hint may be either do (prohibit fragmentation, even local one), want (do PMTU discovery, fragment locally when packet size is large), or don't (do not set DF flag).

• netsh interface ipv4 show interfaces

Related terms

• Jumbo frames
• debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
• Path MTU Discovery (PMTUD)
• sysctl: net.ipv4.tcp_mtu_probing
• WireGuard: https://wiki.archlinux.org/index.php/WireGuard#Low_MTU
• iperf: -M, --mss
• tun-mtu in /etc/openvpn/server.conf

See also

• MTU, PMTUD, Jumbo frames, tun-mtu
• Ethernet: MII, MDI, bonding, etherchannel, STP, ARP, MAC, STP, Jumbo frames, 802.1X, MTU, Ethernet In-Band Access (IBA), LACP, Multicast, Broadcast, SPI