Voila le resultat :

[root@portable inflames]# grep -i "\<mtu\>" /etc/* -R
/etc/pcmcia/network.opts: # If you need to override the interface's MTU...
/etc/pcmcia/network.opts: MTU=""
/etc/ppp/ip-up.ipv6to4:# IPV6TO4_MTU=<MTU for IPv6>: controls IPv6 MTU for the 6to4 link (optional, default is MTU of interface - 20)
/etc/ppp/ip-up.ipv6to4: # Get MTU of master device
/etc/ppp/ip-up.ipv6to4: ipv4mtu="`ipv6_exec_ip link show dev $DEVICE | grep -w "mtu" | awk '{ print $5 }'`"
/etc/ppp/ip-up.ipv6to4: # IPv6 tunnel MTU is IPv4 MTU minus 20 for IPv4 header
/etc/ppp/ip-up.ipv6to4: echo $"Warning: configured MTU '$IPV6TO4_MTU' for 6to4 exceeds maximum limit of '$tunnelmtu', ignored"
/etc/sysconfig/network-scripts/ifup:if [ -n "${MTU}" ]; then
/etc/sysconfig/network-scripts/ifup: ip link set ${DEVICE} mtu ${MTU}
/etc/sysconfig/network-scripts/ifup-ipv6:# IPV6_MTU=<MTU for IPv6>: controls IPv6 MTU for this link (optional)
/etc/sysconfig/network-scripts/ifup-ipv6:# Set IPv6 MTU, if given
/etc/sysconfig/network-scripts/ifup-ipv6: # Get MTU of master device
/etc/sysconfig/network-scripts/ifup-ipv6: ipv4mtu="`ipv6_exec_ip link show dev $DEVICE | grep -w "mtu" | awk '{ print $5 }'`"
/etc/sysconfig/network-scripts/ifup-ipv6: # IPv6 tunnel MTU is IPv4 MTU minus 20 for IPv4 header
/etc/sysconfig/network-scripts/ifup-ppp:if [ -n "${MTU}" ] ; then
/etc/sysconfig/network-scripts/ifup-ppp: opts="$opts mtu ${MTU}"
/etc/sysconfig/network-scripts/ifup-sit:# IPV6_MTU=<MTU for IPv6>: controls IPv6 MTU for this link (optional)
/etc/sysconfig/network-scripts/ifup-sit:# Set IPv6 MTU, if given
/etc/sysconfig/network-scripts/network-functions-ipv6:# $4: [<MTU>] : MTU of tunnel device (optional, default is automatic)
/etc/sysconfig/network-scripts/network-functions-ipv6: local mtu=$4
/etc/sysconfig/network-scripts/network-functions-ipv6: # Set MTU, if given
/etc/sysconfig/network-scripts/network-functions-ipv6: if [ ! -z "$mtu" ]; then
/etc/sysconfig/network-scripts/network-functions-ipv6: ipv6_set_mtu $device $mtu
/etc/sysconfig/network-scripts/network-functions-ipv6:## Set IPv6 MTU for a device
/etc/sysconfig/network-scripts/network-functions-ipv6:# $2: <IPv6 MTU>
/etc/sysconfig/network-scripts/network-functions-ipv6: ipv6_log $"Missing parameter 'IPv6 MTU' (arg 2)" err $fn
/etc/sysconfig/network-scripts/network-functions-ipv6: ipv6_log $"Given IPv6 MTU '$ipv6_mtu' is out of range" err $fn
/etc/sysconfig/network-scripts/network-functions-ipv6: ipv6_exec_sysctl net.ipv6.conf.$device.mtu >/dev/null 2>&1
/etc/sysconfig/network-scripts/network-functions-ipv6: ipv6_exec_sysctl -w net.ipv6.conf.$device.mtu=$ipv6_mtu >/dev/null
/etc/sysconfig/network-scripts/init.ipv6-global: # autotunnel interface doesn't require a MTU setup