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Chapter 4 Switched Networks

Chapter 4 Switched Networks. CIS 82 Routing Protocols and Concepts Rick Graziani Cabrillo College graziani@cabrillo.edu Version 6. Chapter 4 - Sections & Objectives. 4.1 LAN Design Explain how switched networks support small to medium-sized businesses.

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Chapter 4 Switched Networks

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  1. Chapter 4Switched Networks CIS 82 Routing Protocols and Concepts Rick Graziani Cabrillo College graziani@cabrillo.edu Version 6

  2. Chapter 4 - Sections & Objectives • 4.1 LAN Design • Explain how switched networks support small to medium-sized businesses. • Explain how data, voice, and video are converged in a switched network. • Describe a switched network in a small to medium-sized business. • 4.2 The Switched Environment • Explain how Layer 2 switches forward data in a small to medium-sized LAN. • Explain how frames are forwarded in a switched network. • Compare a collision domain to a broadcast domain.

  3. LAN Design

  4. Growing Complexity of Networks Next-generation networks need to: • Be secure, reliable, and highly available • Support a globalized workforce • Integrate legacy devices

  5. Elements of a Converged Network • Converged network solutions integrate: • voice systems • IP phones • voice gateways • video support • video conferencing • Primary benefit of the converged network - just one physical network to install and manage.

  6. Multiple Networks • Different services on different networks.

  7. Converged Networks • Different services on the same network.

  8. Cisco Borderless Networks • The Cisco Borderless Network has the following features: • Allows organizations to connect anyone, anywhere, anytime, on any device; securely, reliably, and seamlessly.

  9. Cisco Borderless Networks • Provides the framework to unify wired and wireless access including: • policy-based networking • access control • performance management across many different device types • Provides network services, and user and endpoint services that are all managed by an integrated management solution.

  10. Hierarchy in the Borderless Switched Network • Borderless switched network design guidelines are based on the following principles: • Hierarchical - Facilitates understanding the role of each device at every tier. • Modularity - Allows seamless network expansion and integrated services. • Resiliency – Provides an always available network. • Flexibility - Allows intelligent traffic load sharing. • The three tiers of the hierarchical model are Access, Distribution and Core layers.

  11. Switching • A campus network describes the portion of an enterprise infrastructure that interconnects end devices to services such as intranet resources(residing in the data center) or the Internet. • End devices: computers, laptops, and wireless access points • Intranet resources: web pages, call center applications, file and print services, etc.

  12. Hierarchical Network Design

  13. Flat Networks • Network were first implemented in a “flat” manner where all PCs, servers, and printers are connected to each other using Layer 2 switches. • No subnets for any design purposes. • All devices in the same broadcast domain. • Broadcast packets received by an end device wastes available bandwidth and resources. • This is not significant with a few devices. • However, this is a significant waste of resources and bandwidth in large networks.

  14. Hierarchical Design • Access layer: Grant the user access to network applications and functions. • Distribution layer: Aggregates the access layer switches wiring closets, floors, or other physical domain by leveraging module or Layer 3 switches. • Core layer (backbone): High-speed backbone, which is designed to switch packets as fast as possible. • Routing capabilities (also at distribution) • High level of availability and adapt to changes quickly • It also provides for dynamic scalability

  15. Hierarchical Model • Scalable networks are implemented in a hierarchical manner. • A hierarchical model has the following advantages: • Provides modularity • Increases flexibility • Eases growth and scalability • Provides for network predictability • Reduces troubleshooting complexity

  16. Cisco Campus Designs • This model provides a modular framework that enables flexibility in network design and facilitates implementation and troubleshooting. • Each layer can be focused on specific functions. • The Cisco Campus Architecture fundamentally divides networks or their modular blocks into the following hierarchical layers: • Building Core Layer: • High-speed campus backbone designed to switch packets fast. • Provides high availability and adapts quickly to changes. • Building Distribution Layer: • Aggregates wiring closets and use switches to segment workgroups and isolate network problems • Building Access Layer: • Grant user access to network devices.

  17. Access Layer • The access layer is dedicated to meeting the functions of end-device connectivity. • Connects a wide variety of devices including Layer 2 switches (e.g. Catalyst 2960) connecting workstations, servers, printers, APs, cameras, …. • The access layer is a feature-rich section of the campus network because it is a best practice to apply features (VoIP, PoE, etc.) as close to the edge as possible.

  18. Access Layer Capabilities – What we want(Not necessarily implemented at the access layer)

  19. Distribution Layer • The distribution layer acts as a service and control boundary between the access and core layers. • It consolidates the wiring closets using switches to segment workgroups and isolate network problems in a campus environment.

  20. Distribution Layer • Acts as a services and control boundary between the access layer and the core. • Access layer and the core are dedicated special-purpose layers. • Access layer - Meets the functions of end-device connectivity • Core layer – Provides nonstop connectivity across the entire campus network. • Distribution layer - Serves multiple purposes.

  21. Distribution Layer Summary • When Layer 3 routing is not configured in the access layer, distribution layer: • Provides high availability and equal-cost load sharing by interconnecting the core and access layer via at least dual paths • Generally terminates a Layer 2 domain of a VLAN (subnet) • Routes traffic from terminated VLANs to other VLANs and to the core • Summarizes access layer routes • Implements policy-based connectivity such as traffic filtering, QoS, and security • Provides for an FHRP

  22. Core Layer • Backbone for campus connectivity • High level of redundancy and adapt to changes quickly • Event of the failure of any component (switch, supervisor, line card, or fiber interconnect, power, and so on) • Permit the occasional, but necessary, hardware and software upgrade or change • Minimal control plane configuration

  23. Core Layer • Backbone (core) that binds together all the elements of the campus architecture to include the WAN, the data center, etc. • Core layer interconnects with a data center and edge distribution module to interconnect WAN, remote access, and the Internet. • The network module operates out of band from the network but is still a critical component.

  24. Core Layer Summary • Provides interconnectivity to the data center, the WAN, and other remote networks • High availability, resiliency, and the ability to make software and hardware upgrades without interruption • Designed without direct connectivity to servers, PCs, access points, and so on • Requires core routing capability • Architected for future growth and scalability • Leverages Cisco platforms that support hardware redundancy

  25. Role of Switched Networks • A hierarchical switched LAN allows more flexibility, traffic management, and additional features: • Quality of service • Additional security • Support for wireless networking and connectivity • Support for new technologies.

  26. Form Factors Stackable Configuration Fixed Configuration • Considerations when selecting switches: • Cost • Port Density • Power • Reliability • Port Speed • Frame buffers • Scalability Modular Configuration

  27. The Switched Environment

  28. Frame ForwardingSwitching as a General Concept in Networking and Telecommunications • A LAN switch makes decisions based on two criteria: • Ingress port - where a frame enters the device • Destination address • A LAN switch maintains a table that it uses to determine how to forward traffic. • In the diagram, If a message enters switch port 1 with a destination address of EA, then the switch forwards the traffic out port 4. • Layer 2 Ethernet switches forward frames based on the destination MAC address.

  29. Frame ForwardingVideo Demonstration - MAC Address Tables on Connected Switches • The video explains how a switch builds its MAC address table by recording the MAC address of each device connected to each of its ports.

  30. 5.2.1.4 - MAC Address Tables on Connected Switches

  31. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  32. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  33. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  34. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  35. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 1 00-0A 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  36. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 1 00-0A 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  37. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 1 00-0A 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 X MAC 00-0D C B A X MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0B Source MAC 00-0A FCS Type Data

  38. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 1 00-0A 00-0A 1 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0A Source MAC 00-0B FCS Type Data

  39. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 1 00-0A 00-0A 1 00-0B 3 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0A Source MAC 00-0B FCS Type Data

  40. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address Internet 1 00-0A 00-0A 1 00-0B 3 Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0A Source MAC 00-0B FCS Type Data

  41. 5.2.1.5 - Sending a Frame to the Default Gateway

  42. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  43. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  44. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  45. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D X C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  46. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D X C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  47. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D X C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  48. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D X X B C A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0D Source MAC 00-0A FCS Type Data Destination IP address on a remote network

  49. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 00-0B 3 Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0A Source MAC 00-0D FCS Type Data Source IP address on a remote network

  50. S1 MAC Address Table S2 MAC Address Table Port Port MAC Address MAC Address 1 00-0A 00-0A 1 4 00-0B 3 00-0D Internet Router 3 4 2 1 3 4 2 S1 1 S2 1 2 MAC 00-0D C B A MAC 00-0B MAC 00-0A MAC 00-0C Destination MAC 00-0A Source MAC 00-0D FCS Type Data Source IP address on a remote network

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