cisco-nxos-provider: enable NVE

This commit enables configuring the Network Virtualization Edge
(NVE) interface on cisco NXOS.

It supports the following configuration:
```
interface nve1
  no shutdown
  host-reachability protocol bgp
  advertise virtual-rmac
  source-interface loopback1 anycast loopback2
  global suppress-arp
  global mcast-group 237.0.0.1 L2
  source-interface hold-down-time 300
```

which can be achieved with:
```
nveCfg, err := nve.NewNVE(
  nve.WithHostReachabilityProtocol(nve.HostReachBGP),
  nve.WithAdvertiseVirtualRmac(true),
  nve.WithSourceInterface("Loopback1"),
  nve.WithAnycastInterface("Loopback2"),
  nve.WithSuppressARP(true),
  nve.WithMulticastGroupL2("237.0.0.1"),
  nve.WithHoldDownTime(300),
)
```

Author: nikatza

internal/provider/cisco/nxos/nve/nve.go

@@ -0,0 +1,272 @@
+// SPDX-FileCopyrightText: 2025 SAP SE or an SAP affiliate company and IronCore contributors
+// SPDX-License-Identifier: Apache-2.0
+package nve
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+
+	"github.com/openconfig/ygot/ygot"
+
+	nxos "github.com/ironcore-dev/network-operator/internal/provider/cisco/nxos/genyang"
+	"github.com/ironcore-dev/network-operator/internal/provider/cisco/nxos/gnmiext"
+	"github.com/ironcore-dev/network-operator/internal/provider/cisco/nxos/iface"
+)
+
+var _ gnmiext.DeviceConf = (*NVE)(nil)
+
+type HostReachT uint
+
+const (
+	HostReachFloodAndLearn HostReachT = iota + 1
+	HostReachBGP
+)
+
+var (
+	ErrInvalidInterfaceName    = errors.New("nve: invalid interface name")
+	ErrInvalidInterfaceNumber  = errors.New("nve: interface number must be between 0 and 1023")
+	ErrInvalidHoldDownTime     = errors.New("nve: hold down time must be between 1 and 1500 seconds")
+	ErrInvalidHostReachProto   = errors.New("nve: invalid host reachability protocol")
+	ErrMissingSourceInterface  = errors.New("nve: source interface must be set before setting anycast interface")
+	ErrIdenticalInterfaceNames = errors.New("nve: source and anycast interface names must be different")
+)
+
+// NVE represents the Network Virtualization Edge interface (nve1). This object must be
+// initialized with the NewNVE function.
+type NVE struct {
+	adminSt              bool
+	hostReach            HostReachT
+	advertiseVirtualRmac *bool
+	// the name of the loopback to use as source
+	sourceInterface string
+	// the name of the loopback to use for anycast
+	anycastInterface string
+	suppressARP      *bool
+	// multicast group for L2 VTEP discovery
+	mcastL2 *net.IPAddr
+	// multicast group for L3 VTEP discovery
+	mcastL3      *net.IPAddr
+	holdDownTime uint16 // in seconds
+}
+
+type NVEOption func(*NVE) error
+
+func NewNVE(opts ...NVEOption) (*NVE, error) {
+	n := &NVE{
+		adminSt: true,
+	}
+	for _, opt := range opts {
+		if err := opt(n); err != nil {
+			return nil, err
+		}
+	}
+	return n, nil
+}
+
+// WithAdminState sets the administrative state of the NVE interface. If not set, the default is `up`.
+func WithAdminState(adminSt bool) NVEOption {
+	return func(n *NVE) error {
+		n.adminSt = adminSt
+		return nil
+	}
+}
+
+// WithHostReachabilityProtocol sets the host reachability protocol for the NVE.
+func WithHostReachabilityProtocol(proto HostReachT) NVEOption {
+	return func(n *NVE) error {
+		switch proto {
+		case HostReachBGP, HostReachFloodAndLearn:
+			n.hostReach = proto
+		default:
+			return ErrInvalidHostReachProto
+		}
+		return nil
+	}
+}
+
+// WithAdvertiseVirtualRmac enables or disables the advertisement of the virtual RMAC address for the NVE interface.
+func WithAdvertiseVirtualRmac(enable bool) NVEOption {
+	return func(n *NVE) error {
+		n.advertiseVirtualRmac = ygot.Bool(enable)
+		return nil
+	}
+}
+
+// WithSourceInterface sets the source interface for the NVE. It must be a loopback interface as per the naming convention
+// defined in the `iface` package.
+func WithSourceInterface(loopback string) NVEOption {
+	return func(n *NVE) error {
+		loName, err := iface.ShortNameLoopback(loopback)
+		if err != nil {
+			return ErrInvalidInterfaceName
+		}
+		loNr, err := strconv.Atoi(loName[2:])
+		if err != nil || loNr > 1023 {
+			return ErrInvalidInterfaceNumber
+		}
+		n.sourceInterface = loName
+		return nil
+	}
+}
+
+// WithAnycastInterface sets the anycast interface for the NVE. It must be a loopback interface as per the naming convention
+// defined in the `iface` package. The anycast interface must be different from the source interface. The source interface
+// must be set before setting the anycast interface.
+func WithAnycastInterface(loopback string) NVEOption {
+	return func(n *NVE) error {
+		if n.sourceInterface == "" {
+			return ErrMissingSourceInterface
+		}
+		loName, err := iface.ShortNameLoopback(loopback)
+		if err != nil {
+			return ErrInvalidInterfaceName
+		}
+		loNr, err := strconv.Atoi(loName[2:])
+		if err != nil || loNr > 1023 {
+			return ErrInvalidInterfaceNumber
+		}
+		if loName == n.sourceInterface {
+			return ErrIdenticalInterfaceNames
+		}
+		n.anycastInterface = loName
+		return nil
+	}
+}
+
+// WithSuppressARP sets the NVE to suppress ARP requests for VTEP IP addresses. If not set, the NVE will
+// use the default behavior. When set, this is the equivalent to the configuration statement `global suppress-arp`.
+// This config will not be shown with `show running-config interface nve1` but only over gNMI.
+func WithSuppressARP(enable bool) NVEOption {
+	return func(n *NVE) error {
+		n.suppressARP = ygot.Bool(enable)
+		return nil
+	}
+}
+
+func validateMulticastAddress(addr string) (*net.IPAddr, error) {
+	ip := net.ParseIP(addr)
+	if ip == nil || ip.To4() == nil || !ip.IsMulticast() {
+		return nil, fmt.Errorf("nve: invalid multicast IPv4 address: %s", addr)
+	}
+	return &net.IPAddr{IP: ip}, nil
+}
+
+// WithMulticastGroupL2 configures the global multicast group for the Layer 2 VNI.
+// Addr must be a valid IPv4 multicast address.
+func WithMulticastGroupL2(addr string) NVEOption {
+	return func(n *NVE) error {
+		ip, err := validateMulticastAddress(addr)
+		if err != nil {
+			return err
+		}
+		n.mcastL2 = ip
+		return nil
+	}
+}
+
+// WithMulticastGroupL3 configures the global multicast group for the Layer 3 VNI.
+// Addr must be a valid IPv4 multicast address.
+func WithMulticastGroupL3(addr string) NVEOption {
+	return func(n *NVE) error {
+		ip, err := validateMulticastAddress(addr)
+		if err != nil {
+			return err
+		}
+		n.mcastL3 = ip
+		return nil
+	}
+}
+
+// WithHoldDownTime sets the hold down time for the NVE interface in seconds (1-1500).
+func WithHoldDownTime(seconds uint16) NVEOption {
+	return func(n *NVE) error {
+		if seconds < 1 || seconds > 1500 {
+			return ErrInvalidHoldDownTime
+		}
+		n.holdDownTime = seconds
+		return nil
+	}
+}
+
+// ToYGOT converts the NVE configuration to these gNMI updates:
+//   - enable the NV feature on the device
+//   - configure the NVE interface with the provided settings
+//   - enable the NG-MVPN feature (only if a multicast group for L3 is set)
+func (n *NVE) ToYGOT(_ context.Context, _ gnmiext.Client) ([]gnmiext.Update, error) {
+	updates := []gnmiext.Update{}
+	val := nxos.Cisco_NX_OSDevice_System_EpsItems_EpIdItems_EpList{}
+
+	val.AdminSt = nxos.Cisco_NX_OSDevice_Nw_AdminSt_enabled
+	if !n.adminSt {
+		val.AdminSt = nxos.Cisco_NX_OSDevice_Nw_AdminSt_disabled
+	}
+
+	switch n.hostReach {
+	case HostReachBGP:
+		val.HostReach = nxos.Cisco_NX_OSDevice_Nvo_HostReachT_bgp
+	case HostReachFloodAndLearn:
+		val.HostReach = nxos.Cisco_NX_OSDevice_Nvo_HostReachT_Flood_and_learn
+	default:
+		// No-op
+	}
+
+	val.AdvertiseVmac = n.advertiseVirtualRmac
+
+	if n.sourceInterface != "" {
+		val.SourceInterface = ygot.String(n.sourceInterface)
+		if n.anycastInterface != "" {
+			val.AnycastIntf = ygot.String(n.anycastInterface)
+		}
+	}
+
+	val.SuppressARP = n.suppressARP
+
+	if n.mcastL2 != nil {
+		val.McastGroupL2 = ygot.String(n.mcastL2.String())
+	}
+	if n.mcastL3 != nil {
+		updates = append(updates, gnmiext.EditingUpdate{
+			XPath: "/System/fm-items/ngmvpn-items",
+			Value: &nxos.Cisco_NX_OSDevice_System_FmItems_NgmvpnItems{
+				AdminSt: nxos.Cisco_NX_OSDevice_Fm_AdminState_enabled,
+			},
+		})
+		val.McastGroupL3 = ygot.String(n.mcastL3.String())
+	}
+
+	if n.holdDownTime != 0 {
+		val.HoldDownTime = ygot.Uint16(n.holdDownTime)
+	}
+
+	updates = append(updates, []gnmiext.Update{
+		gnmiext.EditingUpdate{
+			XPath: "/System/fm-items/nvo-items",
+			Value: &nxos.Cisco_NX_OSDevice_System_FmItems_NvoItems{
+				AdminSt: nxos.Cisco_NX_OSDevice_Fm_AdminState_enabled,
+			},
+		},
+		gnmiext.ReplacingUpdate{
+			XPath: "/System/eps-items/epId-items/Ep-list[epId=1]",
+			Value: &val,
+		},
+	}...)
+	return updates, nil
+}
+
+// Reset removes the nve1 interface and disables the NV feature on the device.
+func (n *NVE) Reset(_ context.Context, _ gnmiext.Client) ([]gnmiext.Update, error) {
+	return []gnmiext.Update{
+		gnmiext.DeletingUpdate{
+			XPath: "/System/eps-items/epId-items/Ep-list[epId=1]",
+		},
+		gnmiext.EditingUpdate{
+			XPath: "/System/fm-items/nvo-items",
+			Value: &nxos.Cisco_NX_OSDevice_System_FmItems_NvoItems{
+				AdminSt: nxos.Cisco_NX_OSDevice_Fm_AdminState_disabled,
+			},
+		},
+	}, nil
+}