VMware NSX
Disclaimer: This is a community-maintained open-source project and is not affiliated with, endorsed by, or sponsored by VMware, Inc. or Broadcom Inc. "VMware" and "NSX" are trademarks of Broadcom. Source code is publicly auditable at github.com/vmware-skills/VMware-NSX under the MIT license.
VMware NSX networking management — 33 MCP tools for segments, gateways, NAT, routing, and IPAM.
Domain-focused networking skill for NSX-T / NSX 4.x Policy API.
Companion skills: vmware-nsx-security (DFW/firewall), vmware-aiops (VM lifecycle), vmware-monitor (read-only monitoring), vmware-storage (iSCSI/vSAN), vmware-vks (Tanzu Kubernetes), vmware-aria (metrics/alerts/capacity), vmware-avi (AVI/ALB/AKO), vmware-harden (compliance baselines).
| vmware-pilot (workflow orchestration) | vmware-policy (audit/policy)
What This Skill Does
| Category | Tools | Count | Read / Write |
|---|
| Segments | list, get details, create, update, delete | 5 | 2R / 3W |
| Tier-0 Gateways | list, get details, BGP neighbors, configure BGP | 4 | 3R / 1W |
| Tier-1 Gateways | list, get details, create, update, delete | 5 | 2R / 3W |
| NAT | list rules, create rule, delete rule | 3 | 1R / 2W |
| Static Routes | list, create, delete | 3 | 1R / 2W |
| IP Pools | list, get usage, create pool, delete pool | 4 | 2R / 2W |
| Fabric Inventory | transport zones, transport nodes, edge clusters | 3 | 3R / 0W |
| Health | NSX alarms, transport node status, edge cluster status, manager status | 4 | 4R / 0W |
| Troubleshooting | logical port status, VM-to-segment lookup | 2 | 2R / 0W |
Total: 33 tools (20 read-only + 13 write)
Quick Install
uv tool install vmware-nsx-mgmt
vmware-nsx init # guided setup: writes config + .env (chmod 600, password grep-safe), then verifies
vmware-nsx doctor
When to Use This Skill
- List, create, or modify NSX segments (overlay / VLAN-backed)
- Create or manage Tier-0 / Tier-1 gateways
- Configure NAT rules (SNAT, DNAT, reflexive)
- View or add static routes, check BGP neighbors
- Manage IP pools and subnet allocations
- Check NSX alarms, transport node health, edge cluster status
- Find which segment a VM is connected to
- Troubleshoot logical port status
Use companion skills for:
- Distributed firewall, security groups, DFW rules, IDS/IPS →
vmware-nsx-security
- VM lifecycle, deployment, guest ops →
vmware-aiops
- vSphere inventory, health, alarms, events →
vmware-monitor
- Storage: iSCSI, vSAN, datastores →
vmware-storage
- Tanzu Kubernetes →
vmware-vks
- Load balancing, AVI/ALB, AKO, Ingress →
vmware-avi
| User Intent | Recommended Skill |
|---|
| NSX networking: segments, gateways, NAT, routing, IPAM | vmware-nsx ← this skill |
| NSX security: DFW rules, security groups, IDS/IPS | vmware-nsx-security |
| Read-only vSphere monitoring, alarms, events | vmware-monitor |
| VM lifecycle, deployment, guest ops | vmware-aiops |
| Storage: iSCSI, vSAN, datastores | vmware-storage |
| Tanzu Kubernetes (vSphere 8.x+) | vmware-vks |
| Aria Ops: metrics, alerts, capacity planning | vmware-aria |
| Multi-step workflows with approval | vmware-pilot |
| Compliance baselines (CIS / 等保 / PCI-DSS), drift detection, LLM remediation advisor | vmware-harden (uv tool install vmware-harden) |
| Load balancer, AVI, ALB, AKO, Ingress | vmware-avi (uv tool install vmware-avi) |
| Audit log query | vmware-policy (vmware-audit CLI) |
Common Workflows
Create an App Network (Segment + T1 Gateway + NAT)
Pre-flight (judgment, not blind sequence):
- Subnet conflict check: scan
inventory list-segments and networking list-ip-pools for any overlap with the proposed CIDR. Overlapping subnets cause asymmetric routing or silent blackholing — NSX will not warn you.
- Edge cluster capacity: confirm chosen
--edge-cluster is healthy (inventory list-edge-clusters + health edge-cluster-status ) and not at SR (Service Router) limit. A fully-loaded edge cluster will accept the T1 creation but routing will fail.
- T0 uplink: the parent T0 must already be configured with BGP/static routes upstream — otherwise SNAT works internally but external traffic goes nowhere.
- NAT IP:
--translated IP must be from a routable address pool announced by T0; using a random IP creates a half-working network.
- Always
--dry-run first — once a segment is attached to running VMs, deleting it requires detaching every port.
Steps:
vmware-nsx gateway create-tier1 app-t1 --name app-t1 --edge-cluster --tier0 --dry-run → review, then run for realvmware-nsx segment create app-web-seg --name app-web-seg --tz --subnet vmware-nsx nat create-rule --tier1 app-t1 --rule-id snat-1 --action SNAT --source --translated - Verify end-to-end:
inventory list-segments, networking list-nat-rules app-t1, AND test with a VM attached to the new segment
- On failure: a connection error or HTTP error prints a single teaching line (e.g. 403 → check NSX role privileges; 404 → run the matching list command for the exact ID). Run
vmware-nsx doctor to verify connectivity and credentials, fix, and re-run the failed step — earlier completed steps are idempotent PUTs and safe to re-apply.
Check Network Health
Judgment: don't just enumerate health endpoints — correlate them. The order below maps cause to symptom: if manager is down, transport nodes will look down too (false positive); fix top-down.
vmware-nsx health manager-status — if any manager node is DEGRADED or DOWN, stop here and resolve before trusting downstream signalsvmware-nsx inventory list-transport-nodes then health transport-node-status for any node not UP — flag nodes down ≥ 5 min; transient blips are normalvmware-nsx inventory list-edge-clusters then health edge-cluster-status — verify SR placement is balanced; one edge holding 80% of SRs is a single point of failurevmware-nsx health alarms --severity HIGH (repeat with CRITICAL) — severity filter is exact-match, not "and above"- Cross-check with
vmware-monitor for vSphere host events — a host losing connection to vCenter often masquerades as an NSX problem
Troubleshoot VM Connectivity
Judgment: connectivity failures happen at one of three layers. Identify which layer first, then drill — don't probe randomly.
- Layer 1 — VM-to-segment: VM has no segment, wrong vNIC, or port admin-down →
troubleshoot vm-segment + troubleshoot port-status
- Layer 2 — segment-to-gateway: segment not attached to T1, T1 not connected to T0 →
inventory get-tier1 shows no Tier-0 path
- Layer 3 — gateway-to-upstream: T0 BGP/static missing or SNAT not configured →
networking bgp-neighbors, networking list-nat-rules
Steps (stop as soon as the failing layer is identified):
- Layer 1:
troubleshoot vm-segment my-vm-01 → if no port, check vSphere vNIC binding first
- Layer 1:
troubleshoot port-status → admin-down or DFW-blocked? If DFW, jump to vmware-nsx-security
- Layer 2:
inventory get-tier1 app-t1 → Tier-0 path present and route advertisement enabled? If not, T1↔T0 link broken
- Layer 3:
networking bgp-neighbors tier0-gw → all neighbors ESTABLISHED? Flapping → upstream issue
- Layer 3:
networking list-nat-rules app-t1 → SNAT rule covers the source CIDR? Mis-typed CIDR is the most common cause
Multi-Target Operations
All commands accept --target to operate against a specific NSX Manager from your config (default: the first target in config.yaml), e.g. vmware-nsx inventory list-segments --target nsx-prod.
Usage Mode
| Scenario | Recommended | Why |
|---|
| Local/small models (Ollama, Qwen) | CLI | ~2K tokens vs ~8K for MCP |
| Cloud models (Claude, GPT-4o) | Either | MCP gives structured JSON I/O |
| Automated pipelines | MCP | Type-safe parameters, structured output |
All MCP tools accept an optional target parameter to select which NSX Manager to connect to.
| Category | Tool | Type | Description |
|---|
| Segment | list_segments | Read | List all segments with type, subnet, admin state, port count |
| get_segment | Read | Get segment details including ports and subnet config |
| create_segment | Write | Create overlay or VLAN segment with subnet and gateway |
| update_segment | Write | Update segment properties (name, subnets, gateway link) |
| delete_segment | Write | Delete a segment (warns on connected ports) |
| Tier-0 GW | list_tier0_gateways | Read | List Tier-0 gateways with HA mode and transit subnets |
| get_tier0_gateway | Read | Get Tier-0 details: HA mode, failover, transit subnets |
| get_bgp_neighbors | Read | List BGP neighbor sessions with state, ASN, prefixes |
| configure_tier0_bgp | Write | Configure BGP (local AS, ECMP, inter-SR iBGP) on a Tier-0 |
| Tier-1 GW | list_tier1_gateways | Read | List Tier-1 gateways with linked Tier-0 and route advertisement |
| get_tier1_gateway | Read | Get Tier-1 details: Tier-0 link, route advertisement |
| create_tier1_gateway | Write | Create Tier-1 gateway with edge cluster and Tier-0 link |
| update_tier1_gateway | Write | Update Tier-1 properties (route advertisement, Tier-0 link) |
| delete_tier1_gateway | Write | Delete a Tier-1 gateway (removes default locale-service first) |
| NAT | list_nat_rules | Read | List NAT rules on a Tier-1 gateway |
| create_nat_rule | Write | Create SNAT/DNAT/reflexive NAT rule on a gateway |
| delete_nat_rule | Write | Delete a NAT rule |
| Static Routes | list_static_routes | Read | List static routes on a Tier-1 gateway |
| create_static_route | Write | Add a static route with network and next-hop |
| delete_static_route | Write | Remove a static route |
| IP Pools | list_ip_pools | Read | List IP pools with usage summary |
| get_ip_pool_usage | Read | Show allocation usage for a pool |
| create_ip_pool | Write | Create a new IP address pool with allocation ranges |
| delete_ip_pool | Write | Permanently delete an IP address pool |
| Fabric | list_transport_zones | Read | List transport zones with type (OVERLAY/VLAN) |
| list_transport_nodes | Read | List transport nodes with node type and status |
| list_edge_clusters | Read | List edge clusters with member count and deployment type |
| Health | list_nsx_alarms | Read | List active NSX alarms filtered by severity |
| get_transport_node_status | Read | Transport node connectivity and config status |
| get_edge_cluster_status | Read | Edge cluster member status and failover config |
| get_nsx_manager_status | Read | NSX Manager cluster health and node roles |
| Troubleshoot | get_logical_port_status | Read | Realized state of all ports on a segment |
| get_segment_port_for_vm | Read | Find which segment a VM is connected to by display name |
Write tools require explicit parameters and are audit-logged. Dry-run preview (--dry-run) is a CLI feature; MCP write tools execute directly.
List results are envelopes — read truncated before you summarise
Every list-returning tool above returns {items, returned, limit, total, truncated, hint}, not a bare array. Rows live under items: empty items with truncated: false means the query genuinely matched nothing — report that, not a tool failure. truncated: true means more rows exist — never describe the result as the complete set; re-query as hint instructs. Field semantics, total sourcing, and an example payload: references/capabilities.md.
Local & Small Models
Running with local or small models? See references/agent-guardrails.md for explicit operating rules that keep tool calls reliable.
CLI Quick Reference
# Inventory (read-only)
vmware-nsx inventory list-segments [--target ]
vmware-nsx inventory get-segment
vmware-nsx inventory list-tier0s
vmware-nsx inventory get-tier0
vmware-nsx inventory list-tier1s
vmware-nsx inventory get-tier1
vmware-nsx inventory list-transport-zones
vmware-nsx inventory list-transport-nodes
vmware-nsx inventory list-edge-clusters
# Networking (read-only)
vmware-nsx networking list-nat-rules
vmware-nsx networking bgp-neighbors
vmware-nsx networking list-static-routes
vmware-nsx networking list-ip-pools
vmware-nsx networking ip-pool-usage
# Segment management (write; full option lists in references/cli-reference.md)
vmware-nsx segment create --name --tz [--vlan|--subnet] [--dry-run]
vmware-nsx segment update [--name|--subnet] [--dry-run]
vmware-nsx segment delete [--dry-run]
# Gateway management (write)
vmware-nsx gateway create-tier1 --name [--tier0|--edge-cluster] [--dry-run]
vmware-nsx gateway update-tier1 [--name|--tier0|--advertise] [--dry-run]
vmware-nsx gateway delete-tier1 [--dry-run]
vmware-nsx gateway configure-tier0-bgp --local-as [--ecmp] [--dry-run]
# NAT (write)
vmware-nsx nat create-rule --tier1 --rule-id --action SNAT --source --translated [--dry-run]
vmware-nsx nat delete-rule --tier1 --rule-id [--dry-run]
# Static routes (write)
vmware-nsx route create-static --tier1 --route-id --network --next-hop [--dry-run]
vmware-nsx route delete-static --tier1 --route-id [--dry-run]
# IP pools (write)
vmware-nsx ip-pool create --name --start --end --cidr [--dry-run]
# Health & Troubleshooting (read-only)
vmware-nsx health alarms [--severity CRITICAL]
vmware-nsx health transport-node-status
vmware-nsx health edge-cluster-status
vmware-nsx health manager-status
vmware-nsx troubleshoot port-status
vmware-nsx troubleshoot vm-segment
# Diagnostics
vmware-nsx doctor [--skip-auth]
Full CLI reference with all options and output formats: see references/cli-reference.md
Troubleshooting
"Segment not found" when querying
Segment display names and Policy API IDs can differ. Use vmware-nsx inventory list-segments to get the exact ID. The Policy API uses the segment id field, not display_name. Common mistakes: using the display name with spaces instead of the hyphenated ID.
NAT rule creation fails with "gateway not found"
NAT rules are created on Tier-1 gateways (or Tier-0 for some topologies). Verify the gateway name with vmware-nsx inventory list-tier1s. The gateway must have an edge cluster assigned for NAT to function.
BGP neighbor shows "Connect" or "Active" state
The BGP session is not established. Common causes:
- Peer IP unreachable from the edge node — check physical uplinks and VLAN config
- ASN mismatch — compare local and remote ASN in
bgp-neighbors output
- Firewall blocking TCP 179 — check edge node firewall rules (not NSX DFW)
- MD5 password mismatch — verify authentication settings on both sides
Transport node status "degraded"
A transport node in degraded state has partial connectivity. Steps:
- Check
vmware-nsx health transport-nodes for the specific failure reason
- Common cause: tunnel endpoint (TEP) unreachable — verify underlay MTU (minimum 1600 for Geneve)
- Check NTP sync between NSX Manager and transport nodes
- If recently upgraded, verify the host switch config matches NSX Manager expectations
"Password not found" error
The password environment variable is missing. Variable names follow the pattern VMWARE_NSX__PASSWORD where hyphens become underscores. Example: target nsx-prod needs VMWARE_NSX_NSX_PROD_PASSWORD. Check your ~/.vmware-nsx/.env file.
Safety
- Read-heavy: 20 of 33 tools are read-only (list, get, status, health, troubleshoot)
- Audit logging: All operations logged to
~/.vmware/audit.db (SQLite WAL, via vmware-policy) with timestamp, user, target, operation, parameters, and result
- Double confirmation: CLI write commands require two separate confirmation prompts before executing
- Dry-run mode: All CLI write commands support
--dry-run to preview API calls without executing (MCP write tools execute directly and are audit-logged)
- Dependency checks: Segment delete checks for connected ports; gateway delete checks for connected segments; prevents accidental cascade failures
- Input validation: CIDR networks validated, IP addresses checked, gateway existence verified before NAT/route operations
- Prompt injection defense: NSX object names returned from the API are sanitized via
_sanitize() — strips control characters, truncates to 500 chars
- Credential safety: Passwords loaded only from environment variables (
.env file), never from config.yaml
- No firewall operations: Cannot create, modify, or delete DFW rules, security groups, or IDS/IPS policies — that scope belongs to
vmware-nsx-security
Setup
uv tool install vmware-nsx-mgmt
vmware-nsx init # writes ~/.vmware-nsx/config.yaml + .env (chmod 600), then verifies
vmware-nsx doctor
All tools are automatically audited via vmware-policy. Audit logs: vmware-audit log --last 20
Full setup guide with multi-target config, MCP server setup, and Docker: see references/setup-guide.md
Architecture
User (natural language)
|
AI Agent (Claude Code / Goose / Cursor)
| reads SKILL.md
vmware-nsx CLI or MCP server (stdio transport)
| NSX Policy API (REST/JSON over HTTPS)
NSX Manager
|
Segments / Gateways / NAT / Routes / IP Pools / Transport Nodes
Audit & Safety
All operations are automatically audited via vmware-policy (@vmware_tool decorator):
- Every tool call logged to
~/.vmware/audit.db (SQLite, framework-agnostic)
- Policy rules enforced via
~/.vmware/rules.yaml (deny rules, maintenance windows, risk levels)
- Risk classification: each tool tagged as low/medium/high/critical
- View recent operations:
vmware-audit log --last 20
- View denied operations:
vmware-audit log --status denied
vmware-policy is automatically installed as a dependency — no manual setup needed.
License
MIT — github.com/vmware-skills/VMware-NSX