diff --git a/neutron_lib/db/constants.py b/neutron_lib/db/constants.py
index 966728396..dada51417 100644
--- a/neutron_lib/db/constants.py
+++ b/neutron_lib/db/constants.py
@@ -24,6 +24,7 @@ MAC_ADDR_FIELD_SIZE = 32
 RESOURCE_TYPE_FIELD_SIZE = 255
 FQDN_FIELD_SIZE = 255
 AZ_HINTS_DB_LEN = 255
+ETHERTYPE_FIELD_SIZE = 40
 
 # Alembic branches
 EXPAND_BRANCH = 'expand'