+test_pmtu_vti4_link_add_mtu() {
+ setup namespaces || return 2
+
+ ${ns_a} ip link add vti4_a type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
+ [ $? -ne 0 ] && err " vti not supported" && return 2
+ ${ns_a} ip link del vti4_a
+
+ fail=0
+
+ min=68
+ max=$((65528 - 20))
+ # Check invalid values first
+ for v in $((min - 1)) $((max + 1)); do
+ ${ns_a} ip link add vti4_a mtu ${v} type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10 2>/dev/null
+ # This can fail, or MTU can be adjusted to a proper value
+ [ $? -ne 0 ] && continue
+ mtu="$(link_get_mtu "${ns_a}" vti4_a)"
+ if [ ${mtu} -lt ${min} -o ${mtu} -gt ${max} ]; then
+ err " vti tunnel created with invalid MTU ${mtu}"
+ fail=1
+ fi
+ ${ns_a} ip link del vti4_a
+ done
+
+ # Now check valid values
+ for v in ${min} 1300 ${max}; do
+ ${ns_a} ip link add vti4_a mtu ${v} type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
+ mtu="$(link_get_mtu "${ns_a}" vti4_a)"
+ ${ns_a} ip link del vti4_a
+ if [ "${mtu}" != "${v}" ]; then
+ err " vti MTU ${mtu} doesn't match configured value ${v}"
+ fail=1
+ fi
+ done
+
+ return ${fail}
+}
+