NETCONF YANG



NETCONF Transport


NETCONF messages are encoded in XML

NETCONF messages are encrypted by SSH
• SSH provides authentication, integrity and confidentiality

NETCONF is connected oriented using TCP



YANG ?

• Data modeling language
• Configuration data
• State data
• Tree structure
• Data and Types



Imports & Includes
YANG Base Types

 • Most YANG elements have a
data type
• Type may be a base type or
derived type
• Derived types may be simple
typedefs or groupings
(structures)
• There are 20+ base types to
start with



 Typedef Statement

 Defines a new simple type

 typedef percent {
type uint16 {
range "0 .. 100";
}
description "Percentage";
}

 leaf completed {
type percent;
}



Common YANG Types
• Commonly used YANG types defined in RFC 6021
• Use
import “ietf-yang-types” {
prefix yang;
}
to reference these
types as e.g.
type yang:counter64;



Grouping Statement
Defines a new structured type
grouping target {
   leaf address {
      type inet:ip-address;
      description "Target IP";
    }
    leaf port {
      type inet:port-number;
     description "Target port number";
    }
}
container peer {
    container destination {
    uses target;
   }
}


container servers {
   container http {
      uses target {
         refine port {
          default 80;
        }
      }
    }
}



YANG Data Definitions
Leaf Statement

 Holds a single value of a particular type
Has no children

 leaf host-name {
   type string;
   mandatory true;
   config true;
   description "Hostname for this system";
}
leaf cpu-temp {
   type int32;
   units degrees-celsius;
   config false;
   description ”Current temperature in CPU";

}


Attributes for leaf






Container Statement
Groups related leafs and containers

 container system {
   container services {
      container ssh {
        presence "Enables SSH";
        description "SSH service specific configuration";
        // more leafs, containers and other things here...
     }
   }
}

Leaf-list Statement
Holds multiple values of a particular type
Has no children
leaf-list domain-search {
   type string;
   ordered-by user;
   description "List of domain names to search";

}



List Statement
list user {
   key name;
   leaf name {
      type string;
   }
   leaf uid {
      type uint32;

   }
  leaf full-name {
     type string;
  }
  leaf class {
     type string;
     default viewer;
 }
}



Attributes for leaf and leaf-list




Keys

 The key field is used to specify
which row we're talking about.
No two rows can have same key value
If we want, we could select the uid to be key instead.



/user[name=‘yang’]/name = yang
/user[name=‘yang’]/uid = 1010
/user[name=‘yang’]/class = admin

/user[name=‘ling’]/class = viewer

Leafref

To make an element reference one of
the rows in a list, set the element type
to leafref

 For lists with multiple keys, the #leafrefs

must match #keys in list

 • A valid leafref can never be
null/empty
– But the parent leaf can be
optional
• A valid leafref can never
point to a row that has
been deleted or renamed
• System checks validity of
leafrefs automatically



Here, the RIP routing
subsystem has a list of
leafrefs pointing out existing

interfaces

 container rip {
   list network-ifname {
       key ifname;
       leaf ifname {
         type leafref {
         path “/interface/name”;
        }
      }
   }
}
YANG RPCs & Notifications
RPC Statement
Administrative actions with input
and output parameters

 rpc activate-software-image {
   input {
     leaf image {
     type binary;
     }
   }
   output {
     leaf status {
     type string;
     }
   }

}



Notification Statement

 Notification with output parameters

 notification config-change {
   description 
      ”The configuration changed";
   leaf operator-name {
      type string;
   }
   leaf-list change {
      type instance-identifier;
  }

}


Instance-identifier values:

 <change>/ex:system/ex:services/ex:ssh/ex:port</change>
<change>/ex:system/ex:user[ex:name='fred']/ex:type</change>

<change>/ex:system/ex:server[ex:ip='192.0.2.1'][ex:port='80’]</change>

opendaylight-inventory.yang 
module opendaylight-inventory {
    namespace "urn:opendaylight:inventory";
    prefix inv;
    typedef node-id {
        type inet:uri;
    }
    typedef node-connector-id {
        type inet:uri;
    }
    typedef node-ref {
        type instance-identifier;
    }
    typedef node-connector-ref {
        type instance-identifier;
    }


    grouping node {
        leaf id {
            type node-id;
        }
        list "node-connector" {
            key "id";
            uses node-connector;
        }
    }
    grouping node-connector {
        leaf id {
            type node-connector-id;
        }
    }
    container nodes {
        list node {
            key "id";
            uses node;
   . . .
        }
    }


Augmentation made by
OpenFlow plugin for storing:
1. All switch description
2. All OpenFlow features
3. All tables and its flows
4. All meters, groups



    notification node-updated {
        status deprecated;
        leaf node-ref {
            type node-ref;
        }
        uses node;
    }
    notification node-connector-updated {
        status deprecated;
        leaf node-connector-ref {
            type node-connector-ref;
        }
        uses node-connector;
    }
    notification node-removed {
        status deprecated;
        leaf node-ref {
            type node-ref;
        }
    }
    notification node-connector-removed {
        status deprecated;
        leaf node-connector-ref {
            type node-connector-ref;
        }
    }
}

ODL’s Inventory Config Data Store

 http://localhost:8181/restconf/config/opendaylight-inventory:nodes






ODL’s network-topology.yang (Lithium)
http://localhost:8181/restconf/operational/network-topology:network-topology

module network-topology  {
    namespace "urn:TBD:params:xml:ns:yang:network-topology";
typedef topology-ref {
        type leafref {
            path "/network-topology/topology/inet:uri";
        }
    }
    typedef node-ref {
        type leafref {
            path "/network-topology/topology/node/inet:uri";
        }
    }
    typedef link-ref {
        type leafref {
            path "/network-topology/topology/link/inet:uri";
        }
    }
    grouping tp-attributes {
        leaf tp-id {
            type inet:uri;
        }
        leaf-list tp-ref {
            type tp-ref;
        }


    }




 grouping node-attributes {
        leaf node-id {
            type inet:uri;
        }
        list supporting-node {
            key "node-ref";
            leaf node-ref {
                type node-ref;
            }
        }
    }
 grouping link-attributes {
        leaf link-id {
            type inet:uri;
        }
        container source {
            leaf source-node {
                mandatory true;
                type node-ref;
            }
            leaf source-tp {
                type tp-ref;
            }
        }
        container destination {
            leaf dest-node {
                mandatory true;
                type node-ref;
            }
            leaf dest-tp {
                type tp-ref;
            }
        }
        list supporting-link {
            key "link-ref";
            leaf link-ref {
                type link-ref;
            }
        }
    }



 container network-topology {
        list topology {
            key "topology-id";
            leaf topology-id {
                type inet:uri;
            }
            container topology-types {
            }
            list underlay-topology {
                key "topology-ref";
                leaf topology-ref {
                    type topology-ref;
                }
            }
            list node {
                key "node-id";
                uses node-attributes;
                list termination-point {
                    key "tp-id";
                    uses tp-attributes;
                }
            }
            list link {
                key "link-id";
                uses link-attributes;
            }
        }
    }
}









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