diff --git a/neutron_lib/agent/constants.py b/neutron_lib/agent/constants.py
index eefc3e61a..2c080570d 100644
--- a/neutron_lib/agent/constants.py
+++ b/neutron_lib/agent/constants.py
@@ -21,3 +21,12 @@ LB_EXTENSION_DRIVER = 'linuxbridge'
 MACVTAP_EXTENSION_DRIVER = 'macvtap'
 # Extension driver type for SR-IOV mech driver
 SRIOV_EXTENSION_DRIVER = 'sriov'
+
+
+# Agent states as detected by server, used to reply on agent's state report
+# agent has just been registered
+AGENT_NEW = 'new'
+# agent is alive
+AGENT_ALIVE = 'alive'
+# agent has just returned to alive after being dead
+AGENT_REVIVED = 'revived'
diff --git a/neutron_lib/constants.py b/neutron_lib/constants.py
index f0627ad9b..79fe3facf 100644
--- a/neutron_lib/constants.py
+++ b/neutron_lib/constants.py
@@ -74,6 +74,9 @@ ROUTER_INTERFACE_OWNERS_SNAT = (DEVICE_OWNER_ROUTER_INTF,
                                 DEVICE_OWNER_HA_REPLICATED_INT,
                                 DEVICE_OWNER_DVR_INTERFACE,
                                 DEVICE_OWNER_ROUTER_SNAT)
+
+DEVICE_ID_RESERVED_DHCP_PORT = 'reserved_dhcp_port'
+
 FLOATINGIP_KEY = '_floatingips'
 INTERFACE_KEY = '_interfaces'
 HA_INTERFACE_KEY = '_ha_interface'
@@ -310,6 +313,13 @@ DNS_DOMAIN_DEFAULT = 'openstacklocal.'
 DNS_LABEL_MAX_LEN = 63
 DNS_LABEL_REGEX = "^[a-z0-9-]{1,%d}$" % DNS_LABEL_MAX_LEN
 
+VALID_DSCP_MARKS = [0, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34,
+                    36, 38, 40, 46, 48, 56]
+
+INGRESS_DIRECTION = 'ingress'
+EGRESS_DIRECTION = 'egress'
+VALID_DIRECTIONS = (INGRESS_DIRECTION, EGRESS_DIRECTION)
+
 
 class Sentinel(object):
     """A constant object that does not change even when copied."""
diff --git a/neutron_lib/db/constants.py b/neutron_lib/db/constants.py
index 4dc241f8d..2682834ab 100644
--- a/neutron_lib/db/constants.py
+++ b/neutron_lib/db/constants.py
@@ -27,3 +27,8 @@ FQDN_FIELD_SIZE = 255
 # Alembic branches
 EXPAND_BRANCH = 'expand'
 CONTRACT_BRANCH = 'contract'
+
+# Maximum value integer can take in MySQL and PostgreSQL
+# In SQLite integer can be stored in 1, 2, 3, 4, 6, or 8 bytes,
+# but here it will be limited by this value for consistency.
+DB_INTEGER_MAX_VALUE = 2 ** 31 - 1
diff --git a/releasenotes/notes/rehome-common-constants-8ac9580e52fd3618.yaml b/releasenotes/notes/rehome-common-constants-8ac9580e52fd3618.yaml
new file mode 100644
index 000000000..684e2a8cf
--- /dev/null
+++ b/releasenotes/notes/rehome-common-constants-8ac9580e52fd3618.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - Constants from ``neutron.common.constants`` are now available in
+    neutron-lib. Note that consumers using ``ROUTER_STATUS_ACTIVE`` or
+    ``ROUTER_STATUS_ERROR`` should now just use ``ACTIVE`` and ``ERROR``
+    from ``neutron_lib.constants``.