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Flashcards in Switching Deck (44):
0

Bridge

A prelude to the switch; separates collision domains

1

Main role of LAN switch

Forward Ethernet frames using logic:
1. Decides to forward or filter frame via Dest. MAC
2, Learning MAC address via Source MAC
3. Creating loop free environment via STP
4. Supports full-duplex, doubling its bandwidth available to the device

2

If a frame enters the switch and no source MAC is in the table....

The switch creates an entry in its MAC address table

3

Inactivity timer

Timer for each MAC address entry in the MAC address table of switch; resets back to 0 if it receives frame from same MAC address

4

No destination MAC entry in table...

Switch floods unknown unicast, multicast, and broadcast frames to all ports except the incoming port

5

Store-and-forward processing

switch receives the entire frame before forwarding the first bit of the frame

6

cut-through processing

starts sending the frame out the outport asap; propogates errors b/c FCS is in the Ethernet trailer

7

fragment-free processing

receives the first 64 bytes of the frame before forwarding it, reducing errors

8

Full-duplex

allows devices to transmit and receive at the same time, doubling bandwidth

9

LAN switching summary

-Each port provides dedicated bandwidth to a single device
-Allows multiple simultaneous conversations b/n devices on different ports
-Supports rate adaptation (different Ethernet speeds supported)

10

Switches are in ________ of the OSI model

Layer 2

11

If frame is a known unicast address, but outgoing interface is the same is incoming interface....

switch will filter frame, meaning that the switch simply ignores the frame and doesn't forward it

12

Hubs allow.....

a collision domain to spread from one side of the device to another

13

Only device that can separate broadcast domains are..

Routers

14

Collision domain

a set of NICs for which a frame sent by one NIC could result in a collision with a frame sent by any other NIC in the same collision domain

15

A LAN consists of....

all devices that are on the same broadcast domain

16

Campus LAN

created to support multiple buildings that are in close proximity to each other

17

Access switches

Switches connected directly to end users, providing user access to the LAN

18

Distribution switches

provide a path through which the access switches can forward traffic to each other

19

Core switches

forward traffic between distribution switches

20

Autonegotiation*

each node picks the best options that both nodes support: the fastest speed and the best duplex setting

21

10-BASE-T

CAT3 or better, two pair, 100m

22

100-BASE-T

Fast Ethernet; CAT5 UTP or better; two pair; 100 m

23

1000BASE-T

Gigabit Ethernet; CAT5e UTP or better, four pair; 100 m

24

1000BASE-SX

Multimode fiber; 550 m

25

1000BASE-LX

Multimode fiber; 550 m; 50- and 62.5-micron fiber

26

1000BASE-LX

9-micron single-mode fiber (laser); 5 km

27

IEEE autonegotiation rules

Use slowest speed
If speed is 10, 100 use half duplex; otherwise use full duplex

28

Hub autonegotiation

uses the IEEE rules for choosing default settings, which often results in devices using 10 Mbps and half-duplex

29

The switch CLI can be accessed by three methods...

Telnet, SSH, or the console

30

Console requires...

A connection betweent the serial port of PC and the switch's console port; rollover cable is needed

31

A difference b/n Telnet and SSH

Telnet sends all data as clear-text data while SSH encrypts this

32

Switches can support up to __ simultaneous Telnet sessions

16

33

SSH requires ____ for login

username and password

34

Debug command

Asks the switch to continue monitoring different processes in the switch.

35

Configuration commands

Are commands that tell the switch the details of what to do and how to do it; changes switch configuration immediately

36

Useful debug commands

no debug all
undebug all
debug

37

RAM memory

Used for working storage (active configuration)

38

ROM memory

stores bootstrap program that finds the full Cisco IOS image and manages the process of loading Cisco IOS into RAM

39

Flash memory

Stores Cisco IOS images and default location where the switch gets its Cisco IOS at boot time

40

NVRAM

stores the initial or startup configuration file

41

reload command

erases RAM and copies start config into RAM

42

erase startup-config or erase nvram

erases startup-configuration file

43

terminal monitor (hint: debug)

EXEC (enable) command that sends a copy of all syslog messages, including debug messages, to the Telnet or SSH user who issues this command