Routing Cheat Sheet

Here’s a Routing Cheat Sheet:

  • What is Routing?
    • Routing is the process of selecting the path for sending network traffic between different networks or hosts.
  • Routing Types:
    • Static Routing: Manual configuration of routes by network administrators.
    • Dynamic Routing: Routes are automatically learned and updated by routers using routing protocols.
  • Routing Protocols:
    • OSPF (Open Shortest Path First): Interior Gateway Protocol, often used within an autonomous system.
    • BGP (Border Gateway Protocol): Exterior Gateway Protocol for routing between different autonomous systems.
    • RIP (Routing Information Protocol): Simple and distance-vector based.
    • EIGRP (Enhanced Interior Gateway Routing Protocol): Cisco proprietary protocol.
  • IP Routing Tables:
    • Destination IP Address: The target address for the route.
    • Next Hop: The IP address of the next router or destination.
    • Subnet Mask: Defines the network portion of the IP address.
    • Interface: The network interface through which the packet will be forwarded.
  • Routing Metrics:
    • Hop Count: Number of routers a packet must pass through.
    • Bandwidth: The available bandwidth on a route.
    • Delay: Time it takes for a packet to travel from source to destination.
    • Reliability: The reliability of the route.
  • Static Routing Configuration:
    • Command Example (Cisco):
ip route destination_network subnet_mask next_hop

Dynamic Routing Configuration

OSPF Example:

router ospf process_id
network network_address wildcard_mask area area_id

BGP Example:

router bgp autonomous_system_number
neighbor ip_address remote-as autonomous_system_number

Default Route

Static Default Route:

ip route 0.0.0.0 0.0.0.0 next_hop

Dynamic Default Route (OSPF):

ip route 0.0.0.0 0.0.0.0 [outgoing_interface]
  • Routing Troubleshooting
    • Ping and Traceroute: Useful tools for testing connectivity.
    • Check Routing Table: Verify correct routes are present.
    • Logs and Alerts: Monitor router logs for errors.
  • Routing Best Practices:
    • Security: Implement access control lists (ACLs) to control traffic.
    • Redundancy: Use multiple routes for critical connections.
    • Documentation: Maintain accurate documentation of routing configurations.
  • Common Issues:
    • Incorrect Routes: Check routing table entries.
    • Network Congestion: Monitor bandwidth usage.
    • Routing Protocol Issues: Verify routing protocol configurations.

This cheat sheet covers some essential concepts and commands related to routing. Please note that specific configurations may vary based on the routing equipment or software in use.