diff --git a/etc/l3_agent.ini b/etc/l3_agent.ini
index 29a20de95e7..b3ac40c3382 100644
--- a/etc/l3_agent.ini
+++ b/etc/l3_agent.ini
@@ -64,6 +64,7 @@
 # Name of bridge used for external network traffic. This should be set to
 # empty value for the linux bridge. when this parameter is set, each L3 agent
 # can be associated with no more than one external network.
+# This option is deprecated and will be removed in the M release.
 # external_network_bridge = br-ex
 
 # TCP Port used by Neutron metadata server
diff --git a/neutron/agent/l3/config.py b/neutron/agent/l3/config.py
index dfb72bf1d5d..b55cab5a1e5 100644
--- a/neutron/agent/l3/config.py
+++ b/neutron/agent/l3/config.py
@@ -37,6 +37,7 @@ OPTS = [
                       "running on a centralized node (or in single-host "
                       "deployments, e.g. devstack)")),
     cfg.StrOpt('external_network_bridge', default='br-ex',
+               deprecated_for_removal=True,
                help=_("Name of bridge used for external network "
                       "traffic.")),
     cfg.IntOpt('metadata_port',
diff --git a/neutron/debug/debug_agent.py b/neutron/debug/debug_agent.py
index 0b6e053edbb..7eba7e9e825 100644
--- a/neutron/debug/debug_agent.py
+++ b/neutron/debug/debug_agent.py
@@ -38,6 +38,7 @@ class NeutronDebugAgent(object):
     OPTS = [
         # Needed for drivers
         cfg.StrOpt('external_network_bridge', default='br-ex',
+                   deprecated_for_removal=True,
                    help=_("Name of bridge used for external network "
                           "traffic.")),
     ]