[YANG MODEL] SONiC Yang support for VXLAN (#7294)

Why I did it
SONiC Yang support for VXLAN

How I did it
Added a new sonic-vxlan.yang file.
Please refer to EVPN VXLAN HLD for DB details
https://github.com/Azure/SONiC/tree/master/doc/vxlan/EVPN

How to verify it
Added tests for sonic vxlan yang.

src/sonic-yang-models/doc/Configuration.md

@@ -49,6 +49,7 @@ Table of Contents
          * [Versions](#versions)  
          * [VLAN](#vlan)   
          * [VLAN_MEMBER](#vlan_member)  
+         * [VXLAN](#vxlan)   
          * [Virtual router](#virtual-router)  
          * [WRED_PROFILE](#wred_profile)  
          * [PASSWORD_HARDENING](#password_hardening)  
@@ -1460,6 +1461,37 @@ channel name as object key, and tagging mode as attributes.
 }
 ```
 
+### VXLAN
+
+VXLAN_TUNNEL holds the VTEP source ip configuration.  
+VXLAN_TUNNEL_MAP holds the vlan to vni and vni to vlan mapping configuration.  
+VXLAN_EVPN_NVO holds the VXLAN_TUNNEL object to be used for BGP-EVPN discovered tunnels.
+
+```
+{
+"VXLAN_TUNNEL": {
+        "vtep1": {
+            "src_ip": "10.10.10.10"
+        }
+  }
+"VXLAN_TUNNEL_MAP" : {
+        "vtep1|map_1000_Vlan100": {
+           "vni": "1000",
+           "vlan": "100"
+         },
+        "vtep1|testmap": {
+           "vni": "22000",
+           "vlan": "70"
+         },
+  }
+  "VXLAN_EVPN_NVO": {
+        "nvo1": {
+            "source_vtep": "vtep1"
+        }
+  }
+}
+```
+
 ### Virtual router
 
 The virtual router table allows to insert or update a new virtual router

src/sonic-yang-models/setup.py

@@ -134,6 +134,7 @@ setup(
                          './yang-models/sonic-types.yang',
                          './yang-models/sonic-versions.yang',
                          './yang-models/sonic-vlan.yang',
+                         './yang-models/sonic-vxlan.yang',
                          './yang-models/sonic-vrf.yang',
                          './yang-models/sonic-mclag.yang',
                          './yang-models/sonic-vlan-sub-interface.yang',

src/sonic-yang-models/tests/files/sample_config_db.json

@@ -332,6 +332,12 @@
             }
         },
         "VLAN": {
+            "Vlan100": {
+                "description": "vxlan",
+                "vlanid": "100",
+                "mtu": "9216",
+                "admin_status": "up"
+            },
             "Vlan111": {
                 "description": "svlan",
                 "dhcp_servers": [
@@ -1703,7 +1709,22 @@
               "4": "4"
             }
         },
-
+        "VXLAN_TUNNEL": {
+            "vtep1": {
+                "src_ip": "1.2.3.4"
+            }
+        },
+        "VXLAN_EVPN_NVO": {
+            "nvo1": {
+                "source_vtep": "vtep1"
+            }
+        },
+        "VXLAN_TUNNEL_MAP": {
+            "vtep1|map_100_Vlan100": {
+                "vni" : "100",
+                "vlan": "Vlan100"
+            }
+        },
         "PORT_QOS_MAP": {
            "Ethernet0": {
               "dot1p_to_tc_map" : "Dot1p_to_tc_map1",

src/sonic-yang-models/tests/yang_model_tests/tests/vxlan.json

@@ -0,0 +1,17 @@
+{
+    "VXLAN_VALID_TEST": {
+        "desc": "Valid VXLAN Configuration."
+    },
+    "VXLAN_EVPN_NVO_WITHOUT_VTEP": {
+        "desc": "Configure EVPN_NVO without VXLAN_TUNNEL entry",
+	    "eStrKey" : "LeafRef"
+    },
+    "VXLAN_MAP_WITHOUT_VTEP": {
+        "desc": "Configure VXLAN_TUNNEL_MAP without VXLAN_TUNNEL entry",
+	    "eStrKey" : "LeafRef"
+    },
+    "VXLAN_MAP_OOR_VNI": {
+        "desc": "VNI Out of Range in VXLAN_TUNNEL_MAP TABLE",
+        "eStrKey": "Range"
+    }
+}

src/sonic-yang-models/tests/yang_model_tests/tests_config/vxlan.json

@@ -0,0 +1,129 @@
+{
+    "VXLAN_VALID_TEST": {
+        "sonic-vlan:sonic-vlan": {
+            "sonic-vlan:VLAN": {
+                "VLAN_LIST": [
+                    {
+                        "name": "Vlan100"
+                    }
+                ]
+            }
+         },
+        "sonic-vxlan:sonic-vxlan": {
+            "sonic-vxlan:VXLAN_TUNNEL": {
+                "VXLAN_TUNNEL_LIST": [
+                    {
+                        "name": "vtep1",
+                        "src_ip": "1.2.3.4"
+                    }
+                ]
+             },
+            "sonic-vxlan:VXLAN_EVPN_NVO": {
+                "VXLAN_EVPN_NVO_LIST": [
+                    {
+                        "name": "nvo1",
+                        "source_vtep": "vtep1"
+                    }
+                ]
+             },
+            "sonic-vxlan:VXLAN_TUNNEL_MAP": {
+                "VXLAN_TUNNEL_MAP_LIST": [
+                    {
+                        "name": "vtep1",
+                        "mapname": "map_100_Vlan100",
+                        "vlan": "Vlan100",
+                        "vni": "100"
+                    }
+                ]
+             }
+         }
+    },
+    "VXLAN_EVPN_NVO_WITHOUT_VTEP": {
+        "sonic-vxlan:sonic-vxlan": {
+            "sonic-vxlan:VXLAN_EVPN_NVO": {
+                "VXLAN_EVPN_NVO_LIST": [
+                    {
+                        "name": "nvo1",
+                        "source_vtep": "vtep1"
+                    }
+                ]
+             }
+         }
+    },
+    "VXLAN_MAP_WITHOUT_VTEP": {
+        "sonic-vlan:sonic-vlan": {
+            "sonic-vlan:VLAN": {
+                "VLAN_LIST": [
+                    {
+                        "name": "Vlan100"
+                    }
+                ]
+            }
+         },
+        "sonic-vxlan:sonic-vxlan": {
+            "sonic-vxlan:VXLAN_TUNNEL_MAP": {
+                "VXLAN_TUNNEL_MAP_LIST": [
+                    {
+                        "name": "vtep1",
+                        "mapname": "map_100_Vlan100",
+                        "vlan": "Vlan100",
+                        "vni": "100"
+                    }
+                ]
+             }
+         }
+    },
+    "VXLAN_MAP_WITHOUT_VLAN": {
+        "sonic-vxlan:sonic-vxlan": {
+            "sonic-vxlan:VXLAN_TUNNEL": {
+                "VXLAN_TUNNEL_LIST": [
+                    {
+                        "name": "vtep1",
+                        "src_ip": "1.2.3.4"
+                    }
+                ]
+             },
+            "sonic-vxlan:VXLAN_TUNNEL_MAP": {
+                "VXLAN_TUNNEL_MAP_LIST": [
+                    {
+                        "name": "vtep1",
+                        "mapname": "map_100_Vlan100",
+                        "vlan": "Vlan100",
+                        "vni": "100"
+                    }
+                ]
+             }
+         }
+    },
+    "VXLAN_MAP_OOR_VNI": {
+        "sonic-vlan:sonic-vlan": {
+            "sonic-vlan:VLAN": {
+                "VLAN_LIST": [
+                    {
+                        "name": "Vlan100"
+                    }
+                ]
+            }
+         },
+        "sonic-vxlan:sonic-vxlan": {
+            "sonic-vxlan:VXLAN_TUNNEL": {
+                "VXLAN_TUNNEL_LIST": [
+                    {
+                        "name": "vtep1",
+                        "src_ip": "1.2.3.4"
+                    }
+                ]
+             },
+            "sonic-vxlan:VXLAN_TUNNEL_MAP": {
+                "VXLAN_TUNNEL_MAP_LIST": [
+                    {
+                        "name": "vtep1",
+                        "mapname": "map_100_Vlan100",
+                        "vlan": "Vlan100",
+                        "vni": "16777299"
+                    }
+                ]
+             }
+         }
+    }
+}

src/sonic-yang-models/yang-models/sonic-vxlan.yang

@@ -0,0 +1,126 @@
+module sonic-vxlan {
+    yang-version 1.1;
+    namespace "http://github.com/Azure/sonic-vxlan";
+    prefix svxlan;
+
+    import ietf-yang-types {
+        prefix yang;
+    }
+
+    import ietf-inet-types {
+        prefix inet;
+    }
+
+    import sonic-extension {
+        prefix sonic-ext;
+    }
+    // Comment sonic-vlan import here until libyang back-links issue is resolved for VLAN leaf reference.
+    //import sonic-vlan {
+    //    prefix svlan;
+    //}
+    import sonic-types {
+        prefix stypes;
+    }
+
+
+    organization
+        "SONiC";
+
+    contact
+        "SONiC";
+
+    description
+        "SONIC VXLAN";
+
+    revision 2021-04-12 {
+        description
+            "First revision.";
+    }
+
+    container sonic-vxlan {
+
+        container VXLAN_TUNNEL {
+
+            description "config db VXLAN_TUNNEL table";
+
+            list VXLAN_TUNNEL_LIST {
+
+                key "name";
+                max-elements 1;
+
+                leaf name {
+                /* vni devices are created of the form 'name'-vlanid 
+                   The kernel has a max limit of 15 chars for netdevices.
+                   keeping aside 5 chars for hyphen and vlanid the 
+                   name should have a max of 10 chars */
+
+                    type string {
+                        length 1..10;
+                    }
+                }
+
+                leaf src_ip {
+                    type inet:ipv4-address;
+                }
+            }
+        }
+
+        container VXLAN_TUNNEL_MAP {
+
+            description "config db VXLAN_TUNNEL_MAP table";
+
+            list VXLAN_TUNNEL_MAP_LIST {
+                key "name mapname";
+
+                leaf name {
+                    type leafref {
+                        path "/svxlan:sonic-vxlan/svxlan:VXLAN_TUNNEL/svxlan:VXLAN_TUNNEL_LIST/svxlan:name";
+                    }
+                }
+
+                leaf mapname {
+                    type string;
+                }
+
+                leaf vlan {
+                    mandatory true;
+                    // Comment VLAN leaf reference here until libyang back-links issue is resolved and use VLAN string pattern
+                    // type leafref {
+                    //    path "/svlan:sonic-vlan/svlan:VLAN/svlan:VLAN_LIST/svlan:name";
+                    //}
+                    type string {
+                        pattern 'Vlan([0-9]{1,3}|[1-3][0-9]{3}|[4][0][0-8][0-9]|[4][0][9][0-4])';
+                    }
+
+                }
+
+                leaf vni {
+                    mandatory true;
+                    type stypes:vnid_type;
+                }
+            }
+        }
+
+        container VXLAN_EVPN_NVO {
+
+            description "config db VXLAN_EVPN_NVO table";
+
+            list VXLAN_EVPN_NVO_LIST { 
+
+                key "name";
+                max-elements 1;
+
+                leaf name {
+                    type string;
+                }
+
+                leaf source_vtep {
+                    mandatory true;
+                    type leafref {
+                        path "/svxlan:sonic-vxlan/svxlan:VXLAN_TUNNEL/svxlan:VXLAN_TUNNEL_LIST/svxlan:name";
+                    }
+                }
+            }
+        }
+    }
+}

src/sonic-yang-models/yang-templates/sonic-types.yang.j2

@@ -262,6 +262,14 @@ module sonic-types {
         }
     }
 
+    typedef vnid_type {
+        type uint32 {
+             range "1..16777215";
+        }
+        description
+            "VXLAN Network Identifier";
+    }
+
     {% if yang_model_type == "cvl" %}
     /* Required for CVL */
     container operation {