Cisco Network Diagram Generator

Generate professional Draw.io network topology diagrams from Cisco device configurations using the drawio-network-plot Python library.

Overview

This skill automates the creation of network topology diagrams by:

Parsing Cisco device configurations to extract topology data
Identifying devices, interfaces, connections, and network relationships
Generating Draw.io XML diagrams with proper device icons and layouts
Supporting multi-layer visualization (physical, logical, L2, L3)

Assumption: Device configurations have already been collected. This skill focuses on parsing and visualization, not SSH access or data collection.

Installation

Install required library:

bash

pip install drawio-network-plot --break-system-packages

Quick Start Workflow

Parse configurations - Extract topology data from config files
Build topology model - Create device and connection objects
Generate diagram - Use drawio-network-plot to create XML
Save output - Write to /mnt/user-data/outputs/network-diagram.drawio

Parsing Cisco Configurations

Key Data to Extract

Extract these elements from Cisco configs:

Device Information:

Hostname: hostname <name>
Device type: Infer from model (router/switch/firewall/L3 switch)
Management IP: interface <mgmt> + ip address

Interface Details:

Interface name, status, IP address, subnet mask
VLANs: switchport access vlan, switchport trunk allowed vlan
Descriptions: description <text>
Speed/duplex settings

Layer 2 Connections:

CDP neighbors: Parse show cdp neighbors detail output
LLDP neighbors: Parse show lldp neighbors detail output
Port channels: interface Port-channel, member interfaces

Layer 3 Information:

Static routes: ip route
OSPF: router ospf, network statements, areas
BGP: router bgp, neighbors, AS numbers
EIGRP: router eigrp, network statements
HSRP/VRRP: standby, vrrp configurations

Important: Use references/cisco-parser.md for detailed parsing patterns and regular expressions for each configuration type.

Using drawio-network-plot

Basic Structure

python

from drawio_network_plot import create_graph, Node, Edge

# Create graph
graph = create_graph(filename="network.drawio", direction="LR")

# Add devices as nodes
router = Node(
    id="rtr1",
    label="Core-Router-01",
    device_type="router",
    ip_address="10.0.0.1"
)
graph.add_node(router)

# Add connections as edges
link = Edge(
    source="rtr1",
    target="sw1",
    label="Gi0/0/0 → Gi1/0/1\n10.1.1.0/30"
)
graph.add_edge(link)

# Generate diagram
graph.draw()

Device Types and Icons

Map Cisco devices to appropriate icons:

Router: device_type="router" - Routers, multilayer switches doing L3
Switch: device_type="switch" - L2 switches, access switches
Firewall: device_type="firewall" - ASA, Firepower
Server: device_type="server" - Services, appliances
Cloud: device_type="cloud" - Internet, WAN, external networks
PC: device_type="pc" - End devices, workstations

Layout Strategies

Hierarchical (Top-Down):

python

graph = create_graph(filename="network.drawio", direction="TB")

Best for: Core → Distribution → Access topologies

Left-to-Right:

python

graph = create_graph(filename="network.drawio", direction="LR")

Best for: Service chains, data flows, sequential processing

Manual Positioning:

python

node = Node(id="sw1", label="Switch", x=100, y=200, width=120, height=80)

Best for: Complex topologies, specific physical layouts, data center rows

Edge Labeling Best Practices

Include relevant information on connection labels:

python

# L3 Point-to-Point
Edge(label="Gi0/0 → Gi0/1\n10.1.1.0/30\nOSPF Area 0")

# L2 Trunk
Edge(label="Trunk\nVLANs: 10,20,30,100\n1Gbps")

# Port Channel
Edge(label="Po1 (LACP)\nGi0/1-2\n2Gbps")

Complete Workflow Example

Use scripts/generate_network_diagram.py for a complete implementation:

bash

python scripts/generate_network_diagram.py <config_directory> <output_file>

Or follow this manual workflow:

python

import re
from drawio_network_plot import create_graph, Node, Edge

# 1. Parse configurations
devices = {}
connections = []

for config_file in config_files:
    # Parse device info
    hostname = extract_hostname(config_file)
    device_type = infer_device_type(config_file)
    mgmt_ip = extract_mgmt_ip(config_file)
    
    devices[hostname] = {
        'type': device_type,
        'mgmt_ip': mgmt_ip,
        'interfaces': extract_interfaces(config_file)
    }
    
    # Parse CDP neighbors to find connections
    cdp_neighbors = parse_cdp_neighbors(config_file)
    for neighbor in cdp_neighbors:
        connections.append({
            'source': hostname,
            'source_int': neighbor['local_interface'],
            'target': neighbor['device_id'],
            'target_int': neighbor['remote_interface']
        })

# 2. Create graph
graph = create_graph(filename="network.drawio", direction="TB")

# 3. Add devices
for hostname, info in devices.items():
    node = Node(
        id=hostname,
        label=f"{hostname}\n{info['mgmt_ip']}",
        device_type=info['type']
    )
    graph.add_node(node)

# 4. Add connections (deduplicate bidirectional links)
seen_connections = set()
for conn in connections:
    conn_key = tuple(sorted([
        f"{conn['source']}:{conn['source_int']}", 
        f"{conn['target']}:{conn['target_int']}"
    ]))
    
    if conn_key not in seen_connections:
        edge = Edge(
            source=conn['source'],
            target=conn['target'],
            label=f"{conn['source_int']} ↔ {conn['target_int']}"
        )
        graph.add_edge(edge)
        seen_connections.add(conn_key)

# 5. Generate diagram
graph.draw()

Advanced Features

Multi-Layer Diagrams

Create separate diagrams for different network layers:

Physical Layer: All devices and physical connections Logical Layer: VLANs, broadcast domains, subnets Layer 3: Routers, routing protocols, subnets Security Zones: Firewalls, ACLs, security boundaries

Grouping and Containers

Use containers for logical grouping:

python

from drawio_network_plot import Container

# Create data center container
dc1 = Container(
    id="dc1",
    label="Data Center 1",
    children=["rtr1", "sw1", "sw2", "fw1"]
)
graph.add_container(dc1)

Styling and Customization

Customize colors for different device roles:

python

node = Node(
    id="core-rtr",
    label="Core Router",
    device_type="router",
    fill_color="#FF6B6B",  # Red for core devices
    font_color="#FFFFFF"
)

Adding Metadata

Include additional information as node properties:

python

node = Node(
    id="rtr1",
    label="Core-Router-01",
    device_type="router",
    metadata={
        "model": "ISR4451-X",
        "ios_version": "17.6.3",
        "location": "Building A - MDF",
        "serial": "FDO2148B0X1"
    }
)

Handling Complex Topologies

Large Networks (50+ devices)

For large topologies:

Create hierarchical sub-diagrams by location or function
Use containers to group related devices
Generate separate diagrams for L2 and L3 views
Create summary diagrams showing only core infrastructure

Redundant Paths

Show redundancy clearly:

python

# Primary path
edge1 = Edge(source="rtr1", target="rtr2", label="Primary\nGi0/0", style="solid")
# Backup path  
edge2 = Edge(source="rtr1", target="rtr2", label="Backup\nGi0/1", style="dashed")

MPLS/VPN Topologies

Represent virtual connections:

python

# VPN tunnel
vpn_edge = Edge(
    source="site1-rtr",
    target="site2-rtr",
    label="IPsec VPN\n10.100.0.0/24",
    style="dashed",
    color="#0066CC"
)

Output and Delivery

Save to outputs directory:

python

import shutil
shutil.move("network.drawio", "/mnt/user-data/outputs/network-diagram.drawio")

Generate multiple formats if needed:
- Primary: .drawio (editable XML)
- Export via Draw.io: PNG, SVG, PDF
Provide user with link:

python

print("[View your network diagram](computer:///mnt/user-data/outputs/network-diagram.drawio)")

Troubleshooting

Issue: Overlapping nodes Solution: Use manual positioning or adjust layout direction

Issue: Missing connections
Solution: Verify CDP/LLDP data parsing, check for hostname mismatches

Issue: Incorrect device types Solution: Review device type inference logic, use explicit type mapping

Issue: Too much information on diagram Solution: Create multiple focused diagrams (L2, L3, security) instead of one complex diagram

Best Practices

Start simple: Begin with physical connectivity, add layers incrementally
Validate data: Cross-reference parsed data with source configs before generating diagram
Use meaningful labels: Include interface names, IP addresses, and protocol info
Group logically: Use containers for sites, VLANs, or security zones
Handle missing data gracefully: Use placeholder values when CDP/LLDP is unavailable
Document assumptions: Note which connections are discovered vs. inferred
Provide context: Add title, legend, and timestamp to diagrams

Reference Files

references/cisco-parser.md: Detailed regex patterns and parsing functions for all Cisco configuration types
references/drawio-examples.md: Complete working examples for different network scenarios
scripts/generate_network_diagram.py: Production-ready script with full parsing and generation logic

Common Use Cases

Use Case 1: Data Center Topology

python

# Create top-down diagram with core, aggregation, and access layers
# Group servers by rack, show redundant uplinks

Use Case 2: Branch Office WAN

python

# Show hub-and-spoke topology with MPLS/VPN connections
# Highlight primary and backup WAN links

Use Case 3: VLAN Visualization

python

# Create L2 diagram showing VLAN trunks and access ports
# Color-code by VLAN or security zone

Use Case 4: Routing Protocol View

python

# Show OSPF areas, BGP peerings, route reflectors
# Label edges with metrics and next-hops

Next Steps After Generation

Open diagram in Draw.io (web: app.diagrams.net)
Manually refine layout and positioning as needed
Add annotations, labels, or documentation
Export to PNG/PDF for documentation or presentations
Version control the .drawio file for change tracking

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cisco-network-diagram

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SKILL.md

Cisco Network Diagram Generator

Overview

Installation

Quick Start Workflow

Parsing Cisco Configurations

Key Data to Extract

Using drawio-network-plot

Basic Structure

Device Types and Icons

Layout Strategies

Edge Labeling Best Practices

Complete Workflow Example

Advanced Features

Multi-Layer Diagrams

Grouping and Containers

Styling and Customization

Adding Metadata

Handling Complex Topologies

Large Networks (50+ devices)

Redundant Paths

MPLS/VPN Topologies

Output and Delivery

Troubleshooting

Best Practices

Reference Files

Common Use Cases

Next Steps After Generation