WEEK 10-11

Week 10-11 Routing Protocols

• Routing protocols facilitate routing information exchange between routers. They allow routers to dynamically learn about remote networks and automatically update their routing tables.
• Static routes:
  • Routers can learn static routes in two ways: by examining active interfaces, or by manual configuration.
  • A default route, also known as the gateway of last resort, is a special static route.
• Dynamic routes:
  • Routers learn dynamic routes by running routing protocols.
  • Routing protocols allow routers to communicate with each other and learn about network routes.
  • Protocols learn routes from other neighboring routers that run the same protocol.
  • Routing protocols exchange routing information when topology changes requiring automatic learning of new networks.

Learning Outcomes

• Understanding routers as computers with operating systems and hardware.
• Demonstrating device configuration skills and address application.
• Explaining how routers forward packets to their destinations.
• Discussing administrative distance (AD).
• Describing Switch 2960.

Routing Protocol Types

• Routed protocols: IP, IPX, AppleTalk
• Routing protocols: RIP, IGRP, OSPF, EIGRP, BGP, IS-IS, RIP, NLSP, EIGRP, RMTP, AURP, EIGRP

Dynamic Routing Protocols

• Plays crucial role in today's networks
• Offer dynamic learning, adapting to topology changes.
• Often used with static routes in many networks.

Evolution of Dynamic Routing Protocols

• Presented in a table format: interior gateway protocols (IGP), exterior gateway protocols (EGP), Distance Vector Routing Protocols, Link State Routing Protocols, Path Vector.
  • Protocols and their associated years of development are listed.
  • Specific versions are noted (RIPv1, RIPv2, OSPFv2, BGP, etc.)
  • The classification of protocols (Classful, Classless, IPv6 support) is included in the table.

Role of Dynamic Routing Protocols

• Routing protocols facilitate the exchange of routing information between routers.
• Dynamically learn information about remote networks.
• Determine the best path to each network and update the routing table.
• Automatically learn about new networks and find alternate paths in case of link failure.
• Have less administrative overhead compared to static routing, but use network resources (CPU, bandwidth).

Network Discovery and Routing Table Maintenance

• Discover and maintain up-to-date remote network information.
• Select the best path to destination networks.
• Adapt routing tables based on topology changes.
• Key components of a routing protocol include data structures, algorithms, and routing protocol messages.

Dynamic Routing Protocol Operation

• Routing messages are sent and received on router interfaces.
• Routing information is shared with other compatible routers.
• Routers exchange routing information to learn about remote networks.
• The dynamic protocols react to topology changes.

Static Routing Protocol Advantages & Disadvantages

• Advantages: Less cost, easy maintenance, easier to implement in small networks that aren't predicted to grow.
• Disadvantages: Requires administrator intervention when changes occur, inflexible for growing networks, requires administrator knowledge of the entire network, can be cumbersome to maintain.

Dynamic Routing Protocol Advantages & Disadvantages

• Advantages: Less administrative overload, can automatically adapt to network changes, scalable for growing networks.
• Disadvantages: More intricate implementation, greater CPU utilization, requires administrator skill.

Classifying Dynamic Routing Protocols

• Routing protocols can be categorized by characteristics like IGP/EGP, distance vector/link-state, and classful/classless.

Commonly Used Routing Protocols

• RIP (distance vector), IGRP (distance vector), OSPF (link-state), IS-IS (link-state), EIGRP (advanced distance vector), and BGP (path vector).

Autonomous Systems

• Autonomous systems (AS) group networks under a common administrative control.
• An AS defines boundaries for routing protocols.
• This setup gives organizational benefits with IGPs and EGPs.

IGP versus EGP Routing Protocols

• IGPs operate within a single autonomous system.
• EGPs operate between different autonomous systems, commonly BGP.

Distance Vector and Link-State Routing Protocols

• Distance vector protocols advertise routes based on distance and direction.
• Link-state protocols create a network topology map for optimal path selection.

Classful and Classless Routing Protocols

• Classful: Subnet mask is consistent across the topology.
• Classless: Variable subnet masks.

Dynamic Routing Protocols and Convergence

• Convergence is when all routers' routing tables are consistent.

Metrics

• Various metrics determine the best path (hop count, bandwidth, delay, load, reliability, cost).

Administrative Distance (AD)

• AD values define preference order for routing sources.
• Lower AD values are preferred when there's a selection to choose from different routing sources.
• Directly connected networks have administrative distance 0 which cannot change.
• 255 signals that a source is not trustworthy.

Static Routes and Administrative Distance

• Static routes are manually configured.
• Static routes have an AD value.

Directly Connected Networks and Administrative Distance

• Directly connected networks have a very specific AD.