diff --git a/schemas/extensions.yml b/schemas/extensions.yml
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+# Extensions Schema for EVPN-VXLAN Fabric
+# Custom attributes and fabric-specific configurations
+---
+version: "1.0"
+nodes:
+  # =============================================================================
+  # Fabric (Top-level container for all fabric objects)
+  # =============================================================================
+  - name: Fabric
+    namespace: Infra
+    description: EVPN-VXLAN Fabric definition
+    label: Fabric
+    icon: mdi--vector-polygon
+    default_filter: name__value
+    order_by:
+      - name__value
+    display_labels:
+      - name__value
+    attributes:
+      - name: name
+        kind: Text
+        unique: true
+        description: Fabric name (e.g., arista-evpn-fabric)
+      - name: description
+        kind: Text
+        optional: true
+      - name: underlay_protocol
+        kind: Dropdown
+        default_value: ebgp
+        choices:
+          - name: ebgp
+            label: eBGP
+          - name: ospf
+            label: OSPF
+          - name: isis
+            label: IS-IS
+      - name: overlay_protocol
+        kind: Dropdown
+        default_value: evpn
+        choices:
+          - name: evpn
+            label: EVPN
+          - name: ingress_replication
+            label: Ingress Replication
+      - name: anycast_gateway_mac
+        kind: Text
+        optional: true
+        description: "Shared MAC for anycast gateway (format: xxxx.xxxx.xxxx)"
+    relationships:
+      - name: spine_asn
+        peer: InfraAutonomousSystem
+        cardinality: one
+        optional: true
+        description: AS used by spine layer
+      - name: sites
+        peer: LocationSite
+        cardinality: many
+        optional: true
+
+  # =============================================================================
+  # Underlay P2P Link
+  # =============================================================================
+  - name: UnderlayLink
+    namespace: Infra
+    description: Point-to-point underlay link between devices
+    label: Underlay Link
+    icon: mdi--cable-data
+    display_labels:
+      - local_device__name__value
+      - remote_device__name__value
+    attributes:
+      - name: local_ip
+        kind: IPNetwork
+        description: Local interface IP with mask
+      - name: remote_ip
+        kind: IPNetwork
+        description: Remote interface IP with mask
+      - name: mtu
+        kind: Number
+        default_value: 9214
+    relationships:
+      - name: fabric
+        peer: InfraFabric
+        cardinality: one
+        kind: Parent
+      - name: local_device
+        peer: InfraDevice
+        cardinality: one
+      - name: local_interface
+        peer: InfraInterfaceEthernet
+        cardinality: one
+      - name: remote_device
+        peer: InfraDevice
+        cardinality: one
+      - name: remote_interface
+        peer: InfraInterfaceEthernet
+        cardinality: one
+
+  # =============================================================================
+  # Host Connection
+  # =============================================================================
+  - name: HostConnection
+    namespace: Infra
+    description: Host connection to fabric (single or dual-homed)
+    label: Host Connection
+    icon: mdi--desktop-tower
+    default_filter: hostname__value
+    display_labels:
+      - hostname__value
+    attributes:
+      - name: hostname
+        kind: Text
+        description: Connected host name
+      - name: description
+        kind: Text
+        optional: true
+      - name: connection_type
+        kind: Dropdown
+        default_value: dual_homed
+        choices:
+          - name: single_homed
+            label: Single-Homed
+          - name: dual_homed
+            label: Dual-Homed (MLAG)
+      - name: lacp_mode
+        kind: Dropdown
+        default_value: active
+        choices:
+          - name: active
+            label: Active
+          - name: passive
+            label: Passive
+    relationships:
+      - name: vlans
+        peer: InfraVLAN
+        cardinality: many
+        description: VLANs allowed on this connection
+      - name: mlag_interface
+        peer: InfraMlagInterface
+        cardinality: one
+        optional: true
+        description: MLAG interface for dual-homed
+      - name: lag_interface
+        peer: InfraInterfaceLag
+        cardinality: one
+        optional: true
+        description: LAG for single-homed