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a port is d ynamically allocated.
The frames in the buffer are linked dynamically to the destination port.

Allows the packet to be received on one port and th en transmitted on another port, without moving it to a different
queue.

Layer 2 and Layer 3 Switching
Layer 2 Switching: (CISCO Catalyst 2960 Series)
Performs switching and filtering based only on the OSI Data Link layer (Layer 2) MAC address.
Completely transparent to network protocols and use r applications.
Remember that a Layer 2 switch builds a MAC address table that it uses to make forwarding decisions.
Layer 3 Switching: (CISCO Catalyst 3560 Series)
Functions similarly to a Layer 2 switch but instead of using only the Layer 2 MAC address a Layer 3 sw itch can also
use IP address information.
A Layer 3 switch can also learn which IP addresses are associated with its interfaces.
This allows the Layer 3 switch to direct traffic th roughout the network based on IP address informatio n.
However, Layer 3 switches do not completely replace the need for routers on a network.
Routers perform additional Layer 3 services that La yer 3 switches are not capable of performing.

Switch Concepts and Configuration
Navigating Command-Line Interface Modes
CLI itself is basically the same as a router:
Access modes with a password.
Help Facility and Command History
Configure console and telnet access.
Commands to configure options for each interface.
Commands to verify the status of the switch.
The difference is the functions to be configured:
Commands to create and control VLANs (Chapter 3)
Configure a default gateway.
Manage the MAC Address table.
Switch security.
Access Levels:
User EXEC.
Privileged EXEC.
Configuration Modes:
Global Configuration Mode.
Interface Configuration Mode (and more….)

GUI-Based Alternatives to the CLI:
Cisco Network Assistant.
Configure and manage groups of switches or standalo ne switches.
Free from www.cisco.com with a Cisco ID and Password.
Navigating Command-Line Interface Modes
Cisco View.
Displays a physical view of the switch that you can use to set configuration parameters.
View switch status and performance information.
Purchased separately.
Can be a standalone application or part of a Simple Network Management Protocol (SNMP) platform.
Cisco Device Manager.
Web-based software that is stored in the switch mem ory.
Configure and manage switches.
Access from anywhere in your network through a web browser.
SNMP Network Management.
You can manage switches from a SNMP-compatible mana gement station, such as HP OpenView.
The switch is able to provide comprehensive managem ent information.
SNMP network management is more common in large ent erprise networks.

Using the Help Facility
Word / Command line syntax Help:
Console Error Messages:

Switch Boot Sequence
Switch loads the Boot Loader program.
Small program stored in NVRAM.
CPU Initialization.
POST.
Initializes flash memory.
Loads a default OS image into memory and boots the switch.
The OS then initializes the interfaces using the Ci sco IOS commands found in the operating system conf iguration
file config.text, stored in the switch flash memory.

Prepare to Configure the Switch
A PC connected to the console port.
A terminal emulator application (e.g.. HyperTerminal) is running and configured co rrectly.
Attach the power cord to the switch.
Some Catalyst switches, including the 2950 and 2960 series switches do not have a power button .
Observe the Boot Sequence.
When the switch is powered on, the POST begins.
During POST, the LEDs blink while a series of tests determine that the switch is functioning properly.
Successful: the SYST LED rapidly blinks green.
Fails: the SYST LED turns amber.

The Port Status LEDs turn amber for about 30 seconds as the switch discovers the n etwork topology and searches
for loops.
If the Port Status LEDs turn green, the switch has established a link between the por t and a target, such as a
computer.
Basic Switch Configuration
Key Configuration Sequences:
Switch Management Interface:
To manage a switch remotely using TCP/IP, you need to assign the switch an IP address.
An access layer switch is much like a PC in that yo u need to configure an IP address, a subnet mask, a nd a default
gateway.