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, 3 insertions, 0 deletions

diff --git a/src/conf_mode/interfaces-ethernet.py b/src/conf_mode/interfaces-ethernet.py
index 5468c7bda..1f622c003 100755
--- a/src/conf_mode/interfaces-ethernet.py
+++ b/src/conf_mode/interfaces-ethernet.py
@@ -24,6 +24,7 @@ from vyos.configverify import verify_address
 from vyos.configverify import verify_dhcpv6
 from vyos.configverify import verify_interface_exists
 from vyos.configverify import verify_mtu
+from vyos.configverify import verify_mtu_ipv6
 from vyos.configverify import verify_vlan_config
 from vyos.configverify import verify_vrf
 from vyos.ifconfig import EthernetIf
@@ -42,6 +43,7 @@ def get_config(config=None):
         conf = Config()
     base = ['interfaces', 'ethernet']
     ethernet = get_interface_dict(conf, base)
+
     return ethernet
 
 def verify(ethernet):
@@ -59,6 +61,7 @@ def verify(ethernet):
             raise ConfigError('If duplex is hardcoded, speed must be hardcoded, too')
 
     verify_mtu(ethernet)
+    verify_mtu_ipv6(ethernet)
     verify_dhcpv6(ethernet)
     verify_address(ethernet)
     verify_vrf(ethernet)