Voir :
Peut être utile pour du SAN / NAS :
Connaître la MTU d'une interface
netstat -i ip link |grep mtu
Changer provisoirement la MTU d'une inferface
#ifconfig eth1 mtu 9000 up ip link set eth1 mtu 9000
Changer la MTU sur RedHat
/etc/sysconfig/network-scripts/ifcfg-enp0s9
HWADDR=08:00:27:D9:8B:E7 TYPE=Ethernet BOOTPROTO=none IPADDR=192.168.25.21 PREFIX=24 DEFROUTE=yes IPV4_FAILURE_FATAL=yes IPV6INIT=no NAME=enp0s9 UUID=5f82629e-5117-4d41-902d-090d82053cb2 ONBOOT=yes MTU=9000
Changer la MTU sous RedHat avec NetworkManager
nmcli connection modify eno2 802-3-ethernet.mtu 9000 nmcli connection show eno2 |grep mtu
Changer la MTU d'une interface sur Debian
/etc/network/interfaces.d/eth1
auto eth1
iface eth1 inet static
address 192.168.56.12
netmask 255.255.255.0
mtu 9000
Appliquer les changements
systemctl restart networking
Connaitre la MTU entre deux points
# traceroute --mtu 192.168.56.1 traceroute to 192.168.56.1 (192.168.56.1), 30 hops max, 65000 byte packets 1 192.168.56.1 (192.168.56.1) 0.223 ms F=1500 * 0.446 ms
F=1500
1472 = 1500 - 28
Voir aussi /proc/sys/net/ipv4/ip_no_pmtu_disc
# ping -M do -s 1472 192.168.6.130 PING 192.168.6.130 (192.168.6.130) 1472(1500) bytes of data. 1480 bytes from 192.168.6.130: icmp_req=1 ttl=255 time=0.095 ms 1480 bytes from 192.168.6.130: icmp_req=2 ttl=255 time=0.127 ms ^C --- 192.168.6.130 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 999ms rtt min/avg/max/mdev = 0.095/0.111/0.127/0.016 ms # ping -M do -s 1473 192.168.6.130 PING 192.168.6.130 (192.168.6.130) 1473(1501) bytes of data. ^C --- 192.168.6.130 ping statistics --- 4 packets transmitted, 0 received, 100% packet loss, time 2999ms
Path MTUs are recorded in the routing cache. This can interfere with testing, and in particular, can make a remote MTU restriction appear to be a local one. You can clear the cache using the ip route command.
ip route flush cache