diff --git a/neutron_lib/constants.py b/neutron_lib/constants.py
index 2a70256c7..195f488a0 100644
--- a/neutron_lib/constants.py
+++ b/neutron_lib/constants.py
@@ -328,8 +328,11 @@ VXLAN_ENCAP_OVERHEAD = 30
 
 # For DNS extension
 DNS_DOMAIN_DEFAULT = 'openstacklocal.'
+DNS_LABEL_KEYWORDS = ['project_id', 'project_name', 'user_name', 'user_id']
 DNS_LABEL_MAX_LEN = 63
-DNS_LABEL_REGEX = "^[a-z0-9-]{1,%d}$" % DNS_LABEL_MAX_LEN
+DNS_LABEL_REGEX = "^([a-z0-9-]{1,%d}|%s)$" % (
+                   DNS_LABEL_MAX_LEN,
+                   '<' + '>|<'.join(DNS_LABEL_KEYWORDS) + '>')
 
 # max value for TCP, UDP, SCTP ports
 PORT_MAX = 2**16 - 1