Remove unused variable and unnecessary instance variable in network

This is to change unnecessary instance variable to local variable,
and to remove unused variable to keep code clean.

Change-Id: Ib44edbe9132d4c7a92d833ae41f125facb2c8fb0
diff --git a/tempest/api/network/admin/test_dhcp_agent_scheduler.py b/tempest/api/network/admin/test_dhcp_agent_scheduler.py
index 868771f..485c8f5 100644
--- a/tempest/api/network/admin/test_dhcp_agent_scheduler.py
+++ b/tempest/api/network/admin/test_dhcp_agent_scheduler.py
@@ -32,7 +32,7 @@
         # Create a network and make sure it will be hosted by a
         # dhcp agent: this is done by creating a regular port
         cls.network = cls.create_network()
-        cls.subnet = cls.create_subnet(cls.network)
+        cls.create_subnet(cls.network)
         cls.port = cls.create_port(cls.network)
 
     @decorators.idempotent_id('5032b1fe-eb42-4a64-8f3b-6e189d8b5c7d')
diff --git a/tempest/api/network/admin/test_floating_ips_admin_actions.py b/tempest/api/network/admin/test_floating_ips_admin_actions.py
index c36323a..d760724 100644
--- a/tempest/api/network/admin/test_floating_ips_admin_actions.py
+++ b/tempest/api/network/admin/test_floating_ips_admin_actions.py
@@ -43,9 +43,9 @@
         cls.ext_net_id = CONF.network.public_network_id
         cls.floating_ip = cls.create_floatingip(cls.ext_net_id)
         cls.network = cls.create_network()
-        cls.subnet = cls.create_subnet(cls.network)
-        cls.router = cls.create_router(external_network_id=cls.ext_net_id)
-        cls.create_router_interface(cls.router['id'], cls.subnet['id'])
+        subnet = cls.create_subnet(cls.network)
+        router = cls.create_router(external_network_id=cls.ext_net_id)
+        cls.create_router_interface(router['id'], subnet['id'])
         cls.port = cls.create_port(cls.network)
 
     @decorators.idempotent_id('64f2100b-5471-4ded-b46c-ddeeeb4f231b')
diff --git a/tempest/api/network/admin/test_l3_agent_scheduler.py b/tempest/api/network/admin/test_l3_agent_scheduler.py
index 5a54ae0..e1970b9 100644
--- a/tempest/api/network/admin/test_l3_agent_scheduler.py
+++ b/tempest/api/network/admin/test_l3_agent_scheduler.py
@@ -79,7 +79,7 @@
                     cls.router['id'])['router'].get('distributed', False)
                 if cls.is_dvr_router:
                     cls.network = cls.create_network()
-                    cls.subnet = cls.create_subnet(cls.network)
+                    cls.create_subnet(cls.network)
                     cls.port = cls.create_port(cls.network)
                     cls.routers_client.add_router_interface(
                         cls.router['id'], port_id=cls.port['id'])
diff --git a/tempest/api/network/test_extra_dhcp_options.py b/tempest/api/network/test_extra_dhcp_options.py
index 52507f9..1156275 100644
--- a/tempest/api/network/test_extra_dhcp_options.py
+++ b/tempest/api/network/test_extra_dhcp_options.py
@@ -43,16 +43,16 @@
     def resource_setup(cls):
         super(ExtraDHCPOptionsTestJSON, cls).resource_setup()
         cls.network = cls.create_network()
-        cls.subnet = cls.create_subnet(cls.network)
+        cls.create_subnet(cls.network)
         cls.port = cls.create_port(cls.network)
-        cls.ip_tftp = ('123.123.123.123' if cls._ip_version == 4
-                       else '2015::dead')
-        cls.ip_server = ('123.123.123.45' if cls._ip_version == 4
-                         else '2015::badd')
+        ip_tftp = ('123.123.123.123' if cls._ip_version == 4
+                   else '2015::dead')
+        ip_server = ('123.123.123.45' if cls._ip_version == 4
+                     else '2015::badd')
         cls.extra_dhcp_opts = [
             {'opt_value': 'pxelinux.0', 'opt_name': 'bootfile-name'},
-            {'opt_value': cls.ip_tftp, 'opt_name': 'tftp-server'},
-            {'opt_value': cls.ip_server, 'opt_name': 'server-ip-address'}
+            {'opt_value': ip_tftp, 'opt_name': 'tftp-server'},
+            {'opt_value': ip_server, 'opt_name': 'server-ip-address'}
         ]
 
     @decorators.idempotent_id('d2c17063-3767-4a24-be4f-a23dbfa133c9')
diff --git a/tempest/api/network/test_floating_ips_negative.py b/tempest/api/network/test_floating_ips_negative.py
index 9ccda05..62f8d9d 100644
--- a/tempest/api/network/test_floating_ips_negative.py
+++ b/tempest/api/network/test_floating_ips_negative.py
@@ -44,9 +44,9 @@
         cls.ext_net_id = CONF.network.public_network_id
         # Create a network with a subnet connected to a router.
         cls.network = cls.create_network()
-        cls.subnet = cls.create_subnet(cls.network)
-        cls.router = cls.create_router()
-        cls.create_router_interface(cls.router['id'], cls.subnet['id'])
+        subnet = cls.create_subnet(cls.network)
+        router = cls.create_router()
+        cls.create_router_interface(router['id'], subnet['id'])
         cls.port = cls.create_port(cls.network)
 
     @test.attr(type=['negative'])
diff --git a/tempest/api/network/test_networks.py b/tempest/api/network/test_networks.py
index 1426798..69d4ebe 100644
--- a/tempest/api/network/test_networks.py
+++ b/tempest/api/network/test_networks.py
@@ -34,7 +34,6 @@
     def resource_setup(cls):
         super(BaseNetworkTestResources, cls).resource_setup()
         cls.network = cls.create_network()
-        cls.name = cls.network['name']
         cls.subnet = cls._create_subnet_with_last_subnet_block(cls.network,
                                                                cls._ip_version)
         cls._subnet_data = {6: {'gateway':