tunnels: T3592: Set default TTL to 64

Set default TTL value for tunnels from 0 to 64
There are a lot of situation when default value 0 (inherit)
not work properly when you have routing configuration for OSPF
or BGP over the tunnels. To fix it you need explicit set TTL
value other then 0. Or hardcode another value as default.

interface-definitions/interfaces-tunnel.xml.in

@@ -240,6 +240,9 @@
                   #include <include/interface/interface-parameters-key.xml.i>
                   #include <include/interface/interface-parameters-tos.xml.i>
                   #include <include/interface/interface-parameters-ttl.xml.i>
+                  <leafNode name="ttl">
+                    <defaultValue>64</defaultValue>
+                  </leafNode>
                 </children>
               </node>
               <node name="ipv6">

smoketest/scripts/cli/test_interfaces_tunnel.py

@@ -189,6 +189,7 @@ def test_tunnel_parameters_gre(self):
         self.cli_set(self._base_path + [interface, 'parameters', 'ip', 'no-pmtu-discovery'])
         self.cli_set(self._base_path + [interface, 'parameters', 'ip', 'key', gre_key])
         self.cli_set(self._base_path + [interface, 'parameters', 'ip', 'tos', tos])
+        self.cli_set(self._base_path + [interface, 'parameters', 'ip', 'ttl', '0'])
 
         # Check if commit is ok
         self.cli_commit()
@@ -221,7 +222,7 @@ def test_gretap_parameters_change(self):
         self.assertEqual(encapsulation, conf['linkinfo']['info_kind'])
         self.assertEqual(self.local_v4, conf['linkinfo']['info_data']['local'])
         self.assertEqual(remote_ip4,    conf['linkinfo']['info_data']['remote'])
-        self.assertEqual(0,             conf['linkinfo']['info_data']['ttl'])
+        self.assertEqual(64,           conf['linkinfo']['info_data']['ttl'])
 
         # Change remote ip address (inc host by 2
         new_remote = inc_ip(remote_ip4, 2)
@@ -258,7 +259,7 @@ def test_erspan_v1(self):
         self.assertEqual(encapsulation,     conf['linkinfo']['info_kind'])
         self.assertEqual(self.local_v4,     conf['linkinfo']['info_data']['local'])
         self.assertEqual(remote_ip4,        conf['linkinfo']['info_data']['remote'])
-        self.assertEqual(0,                 conf['linkinfo']['info_data']['ttl'])
+        self.assertEqual(64,               conf['linkinfo']['info_data']['ttl'])
         self.assertEqual(f'0.0.0.{ip_key}', conf['linkinfo']['info_data']['ikey'])
         self.assertEqual(f'0.0.0.{ip_key}', conf['linkinfo']['info_data']['okey'])
         self.assertEqual(int(idx),          conf['linkinfo']['info_data']['erspan_index'])
@@ -314,7 +315,7 @@ def test_ip6erspan_v2(self):
         self.assertEqual(encapsulation,     conf['linkinfo']['info_kind'])
         self.assertEqual(self.local_v6,     conf['linkinfo']['info_data']['local'])
         self.assertEqual(remote_ip6,        conf['linkinfo']['info_data']['remote'])
-        self.assertEqual(0,                 conf['linkinfo']['info_data']['ttl'])
+        self.assertEqual(64,               conf['linkinfo']['info_data']['ttl'])
         self.assertEqual(f'0.0.0.{ip_key}', conf['linkinfo']['info_data']['ikey'])
         self.assertEqual(f'0.0.0.{ip_key}', conf['linkinfo']['info_data']['okey'])
         self.assertEqual(erspan_ver,        conf['linkinfo']['info_data']['erspan_ver'])