Information Technology
Rrjeta Kompjuterike. Computer Networks.
Vetëm për qëllime edukative. For Educational Purposes Only.
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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.
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
17.
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.
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
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.
