ifconfig: mtu: disallow MTU < 1280 bytes when IPv6 is enabled on the interface

Using an MTU less then the required 1280 bytes (as per RFC) on an interface
where IPv6 is not explicitly disabled by:

- set interfaces ethernet eth1 ipv6 address no-default-link-local
- not having any other IPv6 address configured

Will now trigger a commit error via verify() instead of raising
FileNotFoundError!

1 files changed, 2 insertions, 0 deletions

diff --git a/src/conf_mode/interfaces-l2tpv3.py b/src/conf_mode/interfaces-l2tpv3.py
index 2653ff19c..1118143e4 100755
--- a/src/conf_mode/interfaces-l2tpv3.py
+++ b/src/conf_mode/interfaces-l2tpv3.py
@@ -24,6 +24,7 @@ from vyos.configdict import get_interface_dict
 from vyos.configdict import leaf_node_changed
 from vyos.configverify import verify_address
 from vyos.configverify import verify_bridge_delete
+from vyos.configverify import verify_mtu_ipv6
 from vyos.ifconfig import L2TPv3If
 from vyos.util import check_kmod
 from vyos.validate import is_addr_assigned
@@ -80,6 +81,7 @@ def verify(l2tpv3):
         raise ConfigError('L2TPv3 local-ip address '
                           '"{local_ip}" is not configured!'.format(**l2tpv3))
 
+    verify_mtu_ipv6(l2tpv3)
     verify_address(l2tpv3)
     return None