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/zw008/VMware-NSX under the MIT license.

VMware NSX networking management — 31 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-pilot (workflow orchestration) | vmware-policy (audit/policy)

What This Skill Does

Category	Tools	Count
Segments	list, get details, create, update, delete, list ports	6
Tier-0 Gateways	list, get details, BGP neighbors, route table	4
Tier-1 Gateways	list, get details, create, update, delete, route table	6
NAT	list rules, get rule details, create rule, update rule, delete rule	5
Static Routes	list, create, delete	3
IP Pools	list, get allocations, create pool, create subnet	4
Health & Troubleshooting	NSX alarms, transport node status, edge cluster status, manager cluster status, logical port status, VM-to-segment lookup	6

Total: 31 tools (18 read-only + 13 write)

Quick Install

uv tool install vmware-nsx-mgmt
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

Related Skills — Skill Routing

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
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 segment list and ipam list-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 (health edge-clusters) 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-t1 app-t1 --edge-cluster <ec> --tier0 <t0> --dry-run → review, then run for real
vmware-nsx segment create app-web-seg --gateway app-t1 --subnet <cidr> --transport-zone tz-overlay
vmware-nsx nat create app-t1 --action SNAT --source <private-cidr> --translated <pub-ip>
Verify end-to-end: segment list, nat list app-t1, AND test with a VM attached to the new segment

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 signals
vmware-nsx health transport-nodes — flag nodes whose tunnel state is not UP for ≥ 5 min; transient blips are normal
vmware-nsx health edge-clusters — verify SR placement is balanced; one edge holding 80% of SRs is a single point of failure
vmware-nsx health alarms — filter to severity ≥ HIGH; lower severities are usually signal noise
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 + port-status
Layer 2 — segment-to-gateway: segment not attached to T1, T1 not connected to T0 → gateway routes-t1 shows no default route
Layer 3 — gateway-to-upstream: T0 BGP/static missing or SNAT not configured → bgp-neighbors, nat list

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 <port-id> → admin-down or DFW-blocked? If DFW, jump to vmware-nsx-security
Layer 2: gateway routes-t1 app-t1 → expected default route present? If not, T1↔T0 link broken
Layer 3: gateway bgp-neighbors tier0-gw → all neighbors ESTABLISHED? Flapping → upstream issue
Layer 3: nat list app-t1 → SNAT rule covers the source CIDR? Mis-typed CIDR is the most common cause

Multi-Target Operations

All commands accept --target <name> to operate against a specific NSX Manager from your config:

# Default target (first in config.yaml)
vmware-nsx segment list

# Specific target
vmware-nsx segment list --target nsx-prod
vmware-nsx health alarms --target nsx-lab

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

MCP Tools (31 — 18 read, 13 write)

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, gateway, transport zone
	`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 (description, tags, DHCP)
	`delete_segment`	Write	Delete a segment (checks for connected ports first)
	`list_segment_ports`	Read	List logical ports on a segment with status
Tier-0 GW	`list_tier0_gateways`	Read	List Tier-0 gateways with HA mode and edge cluster
	`get_tier0_gateway`	Read	Get Tier-0 details: interfaces, routing config, BGP
	`get_tier0_bgp_neighbors`	Read	List BGP neighbor sessions with state, ASN, routes
	`get_tier0_route_table`	Read	Get Tier-0 routing table (connected, static, BGP)
Tier-1 GW	`list_tier1_gateways`	Read	List Tier-1 gateways with linked Tier-0 and edge cluster
	`get_tier1_gateway`	Read	Get Tier-1 details: interfaces, 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, tags)
	`delete_tier1_gateway`	Write	Delete a Tier-1 gateway (checks for connected segments)
	`get_tier1_route_table`	Read	Get Tier-1 routing table
NAT	`list_nat_rules`	Read	List NAT rules on a Tier-1 gateway
	`get_nat_rule`	Read	Get NAT rule details (action, source, destination, translated)
	`create_nat_rule`	Write	Create SNAT/DNAT/reflexive NAT rule on a gateway
	`update_nat_rule`	Write	Update NAT rule properties
	`delete_nat_rule`	Write	Delete a NAT rule
Static Routes	`list_static_routes`	Read	List static routes on a Tier-0 or 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 statistics
	`get_ip_pool_allocations`	Read	Show allocated IPs from a pool
	`create_ip_pool`	Write	Create a new IP address pool
	`create_ip_pool_subnet`	Write	Add a subnet/range to an IP pool
Health	`get_nsx_alarms`	Read	List active NSX alarms with severity and entity
	`get_transport_node_status`	Read	Transport node connectivity and config status
	`get_edge_cluster_status`	Read	Edge cluster member status and failover config
	`get_manager_cluster_status`	Read	NSX Manager cluster health and node roles
Troubleshoot	`get_logical_port_status`	Read	Logical port admin/operational status and link state
	`find_vm_segment`	Read	Find which segment(s) a VM is connected to by name

Read/write split: 18 tools are read-only, 13 modify state. Write tools require explicit parameters and are audit-logged. All write operations support dry-run mode.

CLI Quick Reference

# Segments
vmware-nsx segment list [--target <name>]
vmware-nsx segment get <segment-name>
vmware-nsx segment create <name> --gateway <t1> --subnet <cidr> --transport-zone <tz> [--dry-run]
vmware-nsx segment update <name> --description "new desc" [--dry-run]
vmware-nsx segment delete <name> [--dry-run]
vmware-nsx segment ports <segment-name>

# Tier-0 Gateways
vmware-nsx gateway list-t0
vmware-nsx gateway get-t0 <name>
vmware-nsx gateway bgp-neighbors <t0-name>
vmware-nsx gateway routes-t0 <t0-name>

# Tier-1 Gateways
vmware-nsx gateway list-t1
vmware-nsx gateway get-t1 <name>
vmware-nsx gateway create-t1 <name> --edge-cluster <ec> --tier0 <t0> [--dry-run]
vmware-nsx gateway update-t1 <name> --route-advertisement connected,nat [--dry-run]
vmware-nsx gateway delete-t1 <name> [--dry-run]
vmware-nsx gateway routes-t1 <t1-name>

# NAT
vmware-nsx nat list <gateway-name>
vmware-nsx nat get <gateway-name> <rule-id>
vmware-nsx nat create <gateway-name> --action SNAT --source <cidr> --translated <ip> [--dry-run]
vmware-nsx nat update <gateway-name> <rule-id> --translated <new-ip> [--dry-run]
vmware-nsx nat delete <gateway-name> <rule-id> [--dry-run]

# Static Routes
vmware-nsx route list <gateway-name>
vmware-nsx route create <gateway-name> --network <cidr> --next-hop <ip> [--dry-run]
vmware-nsx route delete <gateway-name> <route-id> [--dry-run]

# IP Pools
vmware-nsx ippool list
vmware-nsx ippool allocations <pool-id>
vmware-nsx ippool create <name> [--dry-run]
vmware-nsx ippool add-subnet <pool-id> --start <ip> --end <ip> --cidr <cidr> [--dry-run]

# Health & Troubleshooting
vmware-nsx health alarms [--severity CRITICAL]
vmware-nsx health transport-nodes
vmware-nsx health edge-clusters
vmware-nsx health manager-status
vmware-nsx troubleshoot port-status <port-id>
vmware-nsx troubleshoot vm-segment <vm-name>

# 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 segment list 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 gateway list-t1. 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_<TARGET_NAME_UPPER>_PASSWORD where hyphens become underscores. Example: target nsx-prod needs VMWARE_NSX_PROD_PASSWORD. Check your ~/.vmware-nsx/.env file.

Safety

Read-heavy: 18 of 31 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 write commands support --dry-run to preview API calls without executing
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
mkdir -p ~/.vmware-nsx
cp config.example.yaml ~/.vmware-nsx/config.yaml
# Edit config.yaml with your NSX Manager targets

# Add to ~/.vmware-nsx/.env (create if missing, chmod 600):
# VMWARE_NSX_PROD_PASSWORD=<your-password>
chmod 600 ~/.vmware-nsx/.env

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

The MCP server uses stdio transport (local only, no network listener). Connections to NSX Manager use HTTPS on port 443.

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/zw008/VMware-NSX

vmware-nsx

Safety Notice

Copy this and send it to your AI assistant to learn