CML Topology Builder

MCP Server

• Command: cml-mcp (pip-installed, stdio transport)
• Requires: CML_URL, CML_USERNAME, CML_PASSWORD environment variables

Available Tools

Node Management

| Tool | Parameters | What It Does | |------|-----------|-------------| | get_node_defs | none | List all available node definitions (IOSv, NX-OS, IOS-XR, etc.) | | create_node | lab_id/lab_title, node_def, label, x, y | Add a node to a lab | | get_nodes | lab_id/lab_title | List all nodes in a lab | | get_node | lab_id/lab_title, node_id/node_label | Get details of a specific node |

Interface Management

| Tool | Parameters | What It Does | |------|-----------|-------------| | create_interface | lab_id/lab_title, node_id/node_label, slot? | Create a new interface on a node | | get_interfaces | lab_id/lab_title, node_id/node_label | List all interfaces on a node | | get_interface | lab_id/lab_title, node_id/node_label, interface_id/interface_label | Get interface details |

Link Management

| Tool | Parameters | What It Does | |------|-----------|-------------| | create_link | lab_id/lab_title, src_node/src_label, src_intf, dst_node/dst_label, dst_intf | Create a link between two interfaces | | get_links | lab_id/lab_title | List all links in a lab | | get_link | lab_id/lab_title, link_id | Get link details | | set_link_condition | lab_id/lab_title, link_id, bandwidth?, latency?, jitter?, loss? | Set link conditioning (WAN simulation) | | set_link_state | lab_id/lab_title, link_id, state | Set link state (up/down) — simulate link failures |

Annotations

| Tool | Parameters | What It Does | |------|-----------|-------------| | create_annotation | lab_id/lab_title, annotation_type, content, x, y, width?, height? | Add a text/shape annotation | | get_annotations | lab_id/lab_title | List all annotations | | delete_annotation | lab_id/lab_title, annotation_id | Remove an annotation |

Available Node Definitions

Common node types available in CML (use get_node_defs to get the full list):

| Node Definition ID | Description | Typical Use | |--------------------|-------------|-------------| | iosv | Cisco IOSv (IOS 15.x) | Routing, switching labs | | iosvl2 | Cisco IOSv L2 | Layer 2 switching labs | | iosxrv9000 | Cisco IOS XR 9000v | SP, MPLS, Segment Routing | | nxosv9000 | Cisco NX-OS 9000v | Data center, VXLAN | | csr1000v | Cisco CSR 1000v (IOS-XE) | SD-WAN, routing | | cat8000v | Cisco Catalyst 8000v | Enterprise routing | | asav | Cisco ASAv | Firewall labs | | server | Ubuntu/Alpine server | Traffic gen, testing | | external_connector | External bridge | Connect lab to host/internet | | unmanaged_switch | Unmanaged L2 switch | Simple L2 connectivity | | wan_emulator | WAN emulator | Add latency/loss between nodes |

Workflow: Build Topology from Description

When the user describes a topology:

1. Create the lab (or get an existing one via get_lab)
2. Get node definitions: get_node_defs to know what's available
3. Plan the layout: Calculate x,y coordinates for visual placement

• Use a grid layout: 200px spacing horizontally, 200px vertically
• Group by role: core in center, edge on sides, servers at bottom

1. Create nodes: create_node for each device with meaningful labels
2. Create interfaces: create_interface for each connection point
3. Wire links: create_link to connect interface pairs
4. Set conditions (if requested): set_link_condition for WAN links
5. Add annotations: create_annotation for labels, IP addressing plans
6. Report the topology: List all nodes, interfaces, and links

Layout Guidelines

When placing nodes, use this visual grid approach:

Topology Layout (x, y coordinates):

Layer 0 (Top):     Core routers         y=100
Layer 1:           Distribution          y=300
Layer 2:           Access / Leaf         y=500
Layer 3 (Bottom):  Servers / Endpoints   y=700

x spacing: 200px between nodes in the same layer
Center the topology: start x at 100, distribute evenly

Example for a 2-spine, 4-leaf topology:

Spine1: (300, 100)    Spine2: (500, 100)
Leaf1:  (100, 300)    Leaf2:  (300, 300)    Leaf3:  (500, 300)    Leaf4:  (700, 300)
Srv1:   (100, 500)    Srv2:   (300, 500)    Srv3:   (500, 500)    Srv4:   (700, 500)

Link Conditioning

Use set_link_condition to simulate real-world WAN characteristics:

| Scenario | Bandwidth | Latency | Jitter | Loss | |----------|-----------|---------|--------|------| | LAN | (none) | (none) | (none) | (none) | | Metro Ethernet | 100 Mbps | 5 ms | 1 ms | 0% | | WAN (good) | 50 Mbps | 20 ms | 5 ms | 0.1% | | WAN (poor) | 10 Mbps | 100 ms | 20 ms | 1% | | Satellite | 5 Mbps | 300 ms | 50 ms | 2% | | Congested link | 1 Mbps | 200 ms | 100 ms | 5% |

Workflow: Annotate Topology

After building a topology, add visual documentation:

1. Title annotation: Lab name and purpose at the top
2. IP addressing: Annotation blocks showing subnet assignments per link
3. AS numbers: Label BGP AS boundaries
4. Area labels: Mark OSPF areas, VRF names, VLAN IDs
5. Notes: Any special instructions or test scenarios

Workflow: Simulate Link Failure

When testing network resilience:

1. Get the link: get_links to find the link ID between the two nodes
2. Capture baseline: Use execute_command to check routing tables before failure
3. Bring link down: set_link_state with state "down"
4. Observe convergence: Execute show commands on affected nodes (OSPF neighbors, BGP summary, routing table)
5. Optionally capture traffic: Use cml-packet-capture to capture reconvergence traffic
6. Restore link: set_link_state with state "up"
7. Verify recovery: Confirm routing adjacencies re-establish
8. Report: Document failover/failback time and behavior

Important Rules

• Always use get_node_defs first to verify available node types before creating nodes
• Create interfaces before links — you need interface IDs to wire links
• Use descriptive labels — "R1-Core" not "Node1"
• Plan before building — figure out the full topology before starting to create nodes
• Lab must be STOPPED to add nodes — cannot modify topology of a running lab
• Position nodes logically — hierarchical layout makes the topology readable in CML UI
• Record in GAIT — log topology creation for audit trail