Switched networks (LAN Switching – Switches)
- 1. SWITCHED NETWORKS LAN SWITCHING – SWITCHES Pristina, November 2015 Lecturer: Fleurat Govori CompTIA A+
- 2. CONTENT • Converged network • “Hubbed” network • Switched network • Types of Switches • Switch procedures (Boot sequence, bootloader and LED indicators) • Hierarchy in the Switched Network (Core, Distribution and Access) • MAC Address Table • Symmetric and Asymmetric switching • Frame Forwarding Methods • Memory buffering on switches • Multilayer Switch
- 3. INTRODUCTION • A switched network is a computer network which uses only network switches rather than network hubs on Ethernet local area networks. The switches allow for a dedicated connection to each workstation. A switch allows for many conversations to occur simultaneously.
- 4. CONVERGED NETWORK • Converged network deliver voice, video streams, text and graphics between many different types of devices over the same communication channel and network structure.
- 5. “HUBBED” NETWORK • Advantages - Cheap • Disadvantages - Everything
- 6. SWITCHED NETWORK • A switched LAN allows more flexibility, traffic management, and additional features, such as: • Quality of service • Additional security • Support for wireless networking and connectivity • Support for new technologies, such as IP telephony and mobility services Disadvantages - More expensive
- 8. HUBS VS SWITCHES Hub Switch Layer Layer 1 devices of the OSI model. Layer 2 of the OSI model. Ports 4/12 ports 24/48 ports Device Type Passive Device (Without Software) Active Device (With Software) Data transmission Electrical signal or bits Frame (L2 Switch) & Packet (L3 switch) Security No privacy More secure Table Cannot learn or store MAC addresses. MAC address table is key factor in Switches Transmission Mode Half duplex Half/Full duplex Broadcast
- 9. TYPES OF SWITCHES • Fixed Configuration Switches - Features and options are limited to those that originally come with the switch. • Modular Configuration Switches - The chassis accepts line cards that contain the ports • Stackable Configuration Switches - Stackable switches, connected by a special cable, effectively operate as one large switch.
- 15. SWITCH BOOT SEQUENCE 1. Power-on self test (POST). 2. Run boot loader software. 3. Boot loader performs low-level CPU initialization. 4. Boot loader initializes the flash file system 5. Boot loader locates and loads a default IOS operating system software image into memory and passes control of the switch over to the IOS.
- 16. SWITCH LED INDICATORS • Each port on switches have status LED indicator lights. • The following modes are available on switches: - System LED - Redundant Power System (RPS) LED - Port Status LED - Port Duplex LED - Port Speed LED - Power over Ethernet (PoE) Mode LED Presentation
- 18. ACCESSING BOOTLOADER (RECOVERING FROM A SYSTEM CRASH) • The boot loader can also be used to manage the switch if the IOS cannot be loaded. • The boot loader can be accessed through a console connection by: 1. Connecting a PC by console cable to the switch console port. Unplug the switch power cord. 2. Reconnecting the power cord to the switch and press and hold the Mode button. 3. The System LED turns briefly amber and then solid green. Release the Mode button. And the boot loader is loaded.
- 20. HIERARCHY IN THE SWITCHED NETWORK • Core Layer - The core layer is the network backbone. • Distribution Layer - The distribution layer interfaces between the access layer and the core layer to provide many important functions • Access Layer - The primary function of an access layer switch is to provide network access to the user.
- 23. MAC ADDRESS TABLE • Switches use MAC addresses to direct network communications through the switch to the appropriate port toward the destination. Step 1: The switch receives a frame from PC1 on Port 1
- 24. Step 2: The switch examines the source MAC address and compares it to MAC address table.
- 25. Step 3: After the switch has recorded the source address information, the switch examines the destination MAC address and generates an ARP request (if MAC isn’t present in Table)
- 26. Step 4: The destination device (PC3) replies to the frame with a unicast frame addressed to PC1
- 27. • Step 5: The switch enters the source MAC address of PC3 and the port number of the ingress port into the address table. The destination address of the frame and its associated egress port is found in the MAC address table
- 28. Step 6: The switch can now forward frames between these source and destination devices without flooding, because it has entries in the address table that identify the associated ports
- 29. SYMMETRIC AND ASYMMETRIC SWITCHING • Symmetric switching • Asymmetric switching Note: Most switches are now 10/100/1000, which allow you to use them symmetrically or asymmetrically.
- 30. FRAME FORWARDING METHODS ON SWITCHES • Switches use one of the following forwarding methods for switching data between network ports: -Store-and-forward switching - A store-and-forward switch receives the entire frame, and computes the CRC. If the CRC is valid, the switch looks up the destination address, which determines the outgoing interface. The frame is then forwarded out the correct port. -Cut-through switching - Forwards the frame before it is entirely received. At a minimum, the destination address of the frame must be read before the frame can be forwarded.
- 33. MEMORY BUFFERING ON SWITCHES • Port-based Memory Buffering - Frames are stored in queues that are linked to specific incoming and outgoing ports. • Shared Memory Buffering - deposits all frames into a common memory buffer that all the ports on the switch share.
- 34. • Shared Memory Buffering• Port-based Memory Buffering
- 36. SUMMARY In this presentation you learned: • Hub vs Switch network • Switch procedures (Boot sequence, bootloader and LED indicators) • MAC Address Table • Symmetric and Asymmetric switching • Frame Forwarding Methods • Memory buffering on switches • Multilayer Switch
- 37. REFERENCES • http://www.diffen.com • http://www.netacad.com • http://moodle.ubt-uni.net/
- 38. QUESTIONS?
Editor's Notes
- #16: Step 1. First, the switch loads a power-on self-test (POST) program stored in ROM. POST checks the CPU subsystem. It tests the CPU, DRAM, and the portion of the flash device that makes up the flash file system. Step 2. Next, the switch loads the boot loader software. The boot loader is a small program stored in ROM and is run immediately after POST successfully completes. Step 3. The boot loader performs low-level CPU initialization. It initializes the CPU registers that control where physical memory is mapped, the quantity of memory, and memory speed. Step 4. The boot loader initializes the flash file system on the system board. Step 5. Finally, the boot loader locates and loads a default IOS operating system software image into memory and hands control of the switch over to the IOS.