A YANG Data Model for Fabric Topology in Data-Center Networks
Extracted elements (20)
A fabric is modeled as an atomic node in a network topology (analogous to a POD) rather than exposing individual devices and links, allowing clients to consume topology information at the fabric level without needing to be aware of the entire underlay network.
Fabric port termination-point information is read-only (config false) and learned from underlay networks rather than configured at the fabric topology layer, reflecting that port connectivity is derived from physical infrastructure discovery.
Service capabilities (ip-mapping/NAT, acl-redirect/SFC, dynamic-route-exchange) and device roles are defined as identity-refs to allow vendors and users to extend the model by defining new identities without modifying the base module.
The fabric-id typedef is defined as nw:node-id with a note that fabric composition (e.g., via RPC) is left for vendor-specific implementation and is not provided in the model, intentionally keeping the standard model generic.
The fabric topology model augments RFC 8345 (ietf-network and ietf-network-topology) rather than defining a standalone model, enabling integration with L1/L2/L3 topology models and use as a service topology layer that maps to underlay topologies such as L3 as defined in RFC 8346.
The ietf-dc-fabric-topology-state companion module (Appendix A) is provided for non-NMDA-compliant implementations; it mirrors ietf-dc-fabric-topology but augments ietf-network-state and contains only read-only state data. It SHOULD NOT be supported by implementations that support NMDA (RFC 8342).
The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is SSH (RFC 6242). The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS (RFC 8446).
Fabric termination points are augmented with a read-only 'fport-attributes' container (config false) containing name, role (internal/external/access), type (layer2interface, layer3interface, layer2Tunnel, layer3Tunnel), device-port (tp-ref), and a tunnel-option choice.
The 'device-attributes' grouping provides a device-ref (instance-identifier to a node in another topology) and a leaf-list of roles (SPINE, LEAF, Border, or Border-Leaf, default leaf) representing a device's role within a POD.
The 'fabric-attributes' container carries fabric-id, name, type (underlay-network-type identity such as VXLAN, VLAN, or TRILL), vni-capacity (min/max int32 VNI range), description, options, device-nodes, device-links, and device-ports.
The 'fabric-options' grouping defines gateway-mode (centralized or distributed, default distributed) and traffic-behavior (normal or policy-driven, default normal), plus a leaf-list of capability-supported service capabilities.
The fabric-port-type enumeration defines four values: layer2interface (L2 interface), layer3interface (L3 interface), layer2Tunnel (L2 tunnel), and layer3Tunnel (L3 tunnel), used to classify termination points on a fabric.
The ietf-dc-fabric-topology module defines a 'fabric-network' network type by augmenting the 'network-types' container of ietf-network, using a presence container to indicate fabric topology. A fabric is modeled as a node under the network/node container with a 'fabric-attributes' container.
The ietf-dc-fabric-types module defines identity hierarchies for fabric-type (vxlan-fabric, vlan-fabric, trill-fabric), port-type (eth, serial), bandwidth (bw-1M through bw-400G), device-role (spine, leaf, border), fabric-port-role (internal, external, access), and service-capability (ip-mapping, acl-redirect, dynamic-route-exchange).
The 'port-attributes' grouping defines port-ref (tp-ref instance-identifier), port-type (identityref based on port-type identity: ethernet or serial), and bandwidth (identityref supporting speeds from 1M to 400G).
The 'vni-capacity' container in fabric-attributes specifies the range of VXLAN Network Identifiers (VNI) used by the POD, with min and max leaves of type int32.
Three namespace URIs are registered in the 'IETF XML Registry' (RFC 3688): urn:ietf:params:xml:ns:yang:ietf-dc-fabric-types, urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology, and urn:ietf:params:xml:ns:yang:ietf-dc-fabric-topology-state.
Three YANG module names are registered in the 'YANG Module Names' registry (RFC 6020): ietf-dc-fabric-types (prefix: fabrictypes), ietf-dc-fabric-topology (prefix: fabric), and ietf-dc-fabric-topology-state (prefix: sfabric), all referencing RFC 8542.
The read-only 'fport-attributes' data nodes (config false) are also sensitive: a malicious client could attempt to read fabric connection topology including device-port and name without permission. Read access should be controlled via NACM.
The writable 'fabric-attributes' data nodes are sensitive: a malicious client could attempt to sabotage fabric configuration such as device nodes or type. Write operations without proper protection can have a negative effect on network operations. NACM (RFC 8341) provides access control for NETCONF/RESTCONF users.