Networking Chapter 6: Routing Concepts

Chapter 6: Routing Concepts

• Routing is the process of forwarding traffic between networks
• Routers are specialized computers responsible for routing traffic between networks
• Routers use routing tables to determine the best path to send packets
• Routers encapsulate packets and forward them to the appropriate interface
• Routers use static routes and dynamic routing protocols to learn about remote networks and build their routing tables
• Routers use information in data packets to make forwarding decisions
• Routers have multiple interfaces connected to different IP networks, allowing them to connect multiple networks
• Routers use encapsulation and de-encapsulation processes to switch packets between interfaces
• Configuring interfaces with IP addresses and subnet masks enables network access
• Devices need IP addresses, subnet masks, and default gateways to enable network access
• Routers are computers with components like a CPU, OS (Cisco IOS), RAM, ROM, NVRAM, Flash, and hard drive.
• Router components store information like running IOS, configuration file, IP routing, ARP tables, basic diagnostic software, and more

Chapter 6: Objectives

• Configure a router to route between multiple directly connected networks.
• Describe the primary functions and features of a router.
• Explain how routers use information in data packets to make forwarding decisions in a small- to medium-sized business network.
• Explain encapsulation and de-encapsulation process used by routers when switching packets between interfaces.
• Explain routing table entries for directly connected networks, and how a router builds a routing table of directly connected networks
• Explain how to build a routing table using static routes.
• Explain how to build a routing table using a dynamic routing protocol.

Functions of a Router

• Routers interconnect networks through multiple interfaces on different IP networks.
• Routers choose best paths by using static routes and dynamic routing protocols to determine optimal routes to send packets.

Connect Devices

• Configure IP addresses, subnet masks, and default gateways on devices to enable network access.

Document Network Addressing

• Network documentation includes device names, interfaces, IP addresses, subnet masks, and default gateways.

Enable IP on a Switch

• Network infrastructure devices require IP addresses for remote management.
• Switch management IP addresses are assigned on virtual interfaces.

Basic Settings on a Router

• Naming devices distinguishes them, and secures management access (EXEC, user EXEC, and Telnet).
• Routers use banners to provide legal notification of unauthorized access.
• Saves configurations for future use

Configure an IPv4 Router Interface

• Router interfaces must be configured with addresses and subnet masks for availability.
• Activation prevents shutdown and ensures LAN/WAN interfaces are activated
• Optional descriptions can be used for further clarity.

Verify Connectivity of Directly Connected Networks

• Show commands for interface operations and configurations
• Show commands (show ip interfaces brief; show ip route; show running -config) for more detailed information about interfaces

Switching Packets between Networks

• Routers encapsulate packets at layers for switching between networks.
• Routers use a process to forward packets to the next hop, including Layer 2 and Layer 3 data, the MAC (physical address), and router routing table information.

Switching Packets between Networks

• R3 forwards the packet to PC2, encapsulated and de-encapsulated in each network based on routing table information

Path Determination

• Routers determine the best path based on the routing protocol metric
• Dynamic protocols include RIP (Hop count), OSPF (Cost-based cumulative bandwidth), and EIGRP (Bandwidth, delay, load, and reliability)

Load Balancing

• Routers forward packets using multiple paths equally with equal cost load balancing.

Path Determination of the route

• If multiple paths to a destination are configured on a router, the path with the lowest administrative distance (AD) is used.

The Routing Table

• Routing tables in RAM contain information about directly connected routes, remote routes, and network/next-hop associations

Routing Table Sources

• The show ip route command displays the content of the routing table. Includes local routes from interfaces.

Remote Network Routing Entries

• Remote network entries show how the router learned about the network, the destination network, the route source administrative distance, the metric to reach the remote network, the next-hop IP address, time since the network was discovered, and the outgoing interface to reach the remote network.

Directly Connected Routes

• Newly deployed routers without configured interfaces have empty routing tables.
• Active, configured directly connected interfaces create routing table entries.

Static Routes

• Configuration method for specifying explicit paths between devices.
• Static routes are manually configured and require manual updates for topology changes.
• Benefits include security and resource control.
• Command to configure static routes is ip route network mask next-hop-ip /exit-intf.

Static Default Routes

• Default static routes are configured when no routing table path is present for a destination network using ip route 0.0.0.0 0.0.0.0 {exit-intf | next-hop-ip} command

Dynamic Routing Protocols

• Routers share information about reachability and status of remote networks.
• Dynamic routing protocols perform network discovery and maintain routing tables, examples include EIGRP, OSPF, IS-IS, and RIP.

Dive into the fundamentals of routing in networking with this quiz! Explore how routers forward traffic between networks, utilize routing tables, and leverage both static and dynamic protocols. Test your understanding of encapsulation, IP addresses, and subnetting as you learn the intricacies of network connectivity.