Basic Python Concepts for Network Engineers

# Install essential libraries for network automation
pip install pyeapi requests netmiko pyyaml

# String - for hostnames, interface names, etc.
hostname = "thedoodswitch"

# Integers - for VLAN IDs, port numbers, etc.
vlan_id = 100
port_number = 22

# Floating point - for utilization percentages, etc.
interface_utilization = 67.5

# Boolean - for interface status, feature enablement
interface_up = True
ospf_enabled = False

# String operations for network data
hostname = "thedoodswitch.networkdood.com"
location = "DOOD-DC1"

# String methods
print(hostname.split(".")[0])  # Output: thedoodswitch
print(location.startswith("DOOD"))  # Output: True
print(f"Device {hostname} is located at {location}")  # f-strings for formatting

# List of VLANs
vlans = [10, 20, 30, 40, 50]
print(f"First VLAN: {vlans[0]}")  # Access by index

# List of interfaces
interfaces = ["Ethernet1", "Ethernet2", "Management1", "Loopback0"]
print(f"Management interface: {interfaces[2]}")

# Dictionary for device information
device = {
    "hostname": "thedoodswitch",
    "model": "DCS-7280SR-48C6",
    "mgmt_ip": "10.0.0.1",
    "version": "4.28.1F",
    "location": "DOOD-DC1"
}
print(f"Device IP: {device['mgmt_ip']}")

# Check interface status
interface_status = "up"
interface_errors = 0

if interface_status == "up" and interface_errors == 0:
    print("Interface is healthy")
elif interface_status == "up" and interface_errors > 0:
    print("Interface is up but has errors")
else:
    print("Interface is down")

# Check device model for feature compatibility
model = "DCS-7280SR"
if "7280" in model:
    print("Device supports advanced routing features")

# For loop to check multiple interfaces
interfaces = ["Ethernet1", "Ethernet2", "Ethernet3", "Ethernet4"]
for interface in interfaces:
    print(f"Checking configuration on {interface}")

# While loop for a retry mechanism
max_retries = 5
retry_count = 0
connected = False

while not connected and retry_count < max_retries:
    print(f"Attempting to connect (attempt {retry_count + 1})")
    # Connection logic would go here
    connected = True  # Assuming success for this example
    retry_count += 1

def check_vlan_exists(switch_config, vlan_id):
    """
    Check if a VLAN exists in the switch configuration
    
    Args:
        switch_config (str): The switch configuration text
        vlan_id (int): The VLAN ID to check for
        
    Returns:
        bool: True if VLAN exists, False otherwise
    """
    vlan_line = f"vlan {vlan_id}"
    return vlan_line in switch_config

# Example usage
config = """
vlan 10
   name Finance
vlan 20
   name Engineering
vlan 30
   name Marketing
"""

print(check_vlan_exists(config, 20))  # True
print(check_vlan_exists(config, 50))  # False

# Try/except to handle connection issues
import requests

def get_device_info(ip_address):
    try:
        response = requests.get(f"https://{ip_address}/api/v1/device", 
                               verify=False, timeout=5)
        return response.json()
    except requests.exceptions.ConnectionError:
        print(f"Cannot connect to {ip_address}")
        return None
    except requests.exceptions.Timeout:
        print(f"Connection to {ip_address} timed out")
        return None
    except Exception as e:
        print(f"Unexpected error: {str(e)}")
        return None

# Reading a configuration file
def read_config_file(filename):
    try:
        with open(filename, 'r') as file:
            return file.read()
    except FileNotFoundError:
        print(f"Config file {filename} not found")
        return ""

# Writing a backup configuration
def backup_config(device_name, config):
    from datetime import datetime
    timestamp = datetime.now().strftime("%Y%m%d-%H%M%S")
    filename = f"{device_name}-{timestamp}.conf"
    
    with open(filename, 'w') as file:
        file.write(config)
    
    print(f"Backup saved to {filename}")
    return filename