Unit 1 LAN technologies

Flashcards for switching concepts, protocols, and standards.

Switches are _ based and utilize _ to help them make filtering decisions.

Hardware, integrated circuits

Switches move frames of information at __ the Layer of the OSI model.

Data Link

What is the difference between a hub and switch?

A hub operates at Layer 1 and simply repeats signals, while a switch operates at Layer 2 and forwards frames based on MAC addresses.

Allows direct local access to configure a switch using a terminal, or a computer using terminal emulation software for initial configuration. DoD policy states this must be password protected to prevent unauthorized changes. ____

Console Port

This part of the switch is where end devices such as computers and printers are connected. The number of interfaces can vary depending on the model.

Network interfaces

This is where the operating system is saved. Every time that the switch boots up, the flash memory will be accessed to load the OS into the running memory. ____

Flash Memory

Contains information such as the diagnostics and bootup routines. Cannot be accessed or changed.

ROM (Read-Only Memory)

Running memory that the switch uses for operations. Changes to the current configuration are stored in the “running-configuration”.

RAM (Random Access Memory)

Holds the startup-configuration, which is loaded to the RAM upon bootup and then becomes the running-config.

NVRAM (Non-Volatile RAM)

Establishes communication directly between two network devices without relying on any host or network system. Is a data link layer protocol that operates over a point-to-point link.

PPP (Point-to-Point Protocol)

Is a loop-prevention protocol that allows switches to communicate to prevent loops in a network. Defined by IEEE 802.1D.

STP (Spanning Tree Protocol)

Occurs when traffic in one of two directions fail on a link.

Unidirectional Link Failure

Vendor neutral neighbor discovery protocol.

LLDP (Link Layer Discovery Protocol)

Cisco proprietary neighbor discovery protocol that shares information of connected Cisco devices.

CDP (Cisco Discovery Protocol)

What are the two VLAN trunking methods for encapsulating frames? . Which one is non-proprietary? _

ISL and 802.1Q , 802.1Q

switches store the entire frame in internal memory and check the frame for errors before forwarding the frame to its destination.

Store-and-Forward

switching reduces latency; however, bad frames are forwarded, and the destination will ultimately have to request the source send the frame again.

Cut-Through

Switching is a hybrid of Store-and-Forward and Cut-Through switching. It stores the first 64 bytes before forwarding.

Fragment-Free

When two system transmissions occur at the same time, on shared bandwidth, the result is a .

Collision

A late collision indicates that another system attempted to transmit after a host has transmitted at least the .

First 64 bytes of its frame.

What address type does a switch use?

MAC address

Q: What device broadcasts to all ports?

A: Hub

Q: What is address learning?

A: The process of a switch recording MAC addresses and associated ports

Q: What is forwarding/filtering?

A: Sending frames to the correct port or flooding if the destination MAC is unknown

The switch have 5 performance

Hardware based bridging(MAC)

Wire speed

Low latency

Low cost

Broadcast control

Ethernet switches segment a network into multiple collision domains by forwarding frames between segments only when needed. All Layer 2 switches have three basic functions:

Address learning, forward/filtering and loop avoidance

As a result of

the multiple links or use of multiple switches, loops are created which can have a crippling effect on

network wide operation by endlessly repeating the retransmission of a frame. This can cause

instability in the switch’s MAC address table. The instability in turn may present itself as one of the

following problems:

• Broadcast storms

• Multiple frame copies

• Multiple loops

A ____ also known as a network storm, occurs when a network system is overwhelmed

by the continuous multicast of broadcast traffic.

Broadcast Storming

Another problem is a device can receive multiple copies of the same frame of information because

the frame can arrive from different LAN segments at the same time. What is this problem?

Multiple Frame Copies

This is one of the biggest problems is multiple loops generating throughout an internetwork. This means

that loops can occur within other loops.

Multiple Loops