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Flashcards in Switching Deck (44)
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0
Q

Main role of LAN switch

A

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

1
Q

Bridge

A

A prelude to the switch; separates collision domains

2
Q

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

A

The switch creates an entry in its MAC address table

3
Q

Inactivity timer

A

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
Q

No destination MAC entry in table…

A

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

5
Q

Store-and-forward processing

A

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

6
Q

cut-through processing

A

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

7
Q

fragment-free processing

A

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

8
Q

Full-duplex

A

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

9
Q

LAN switching summary

A
  • 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
Q

Switches are in ________ of the OSI model

A

Layer 2

11
Q

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

A

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

12
Q

Hubs allow…..

A

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

13
Q

Only device that can separate broadcast domains are..

A

Routers

14
Q

Collision domain

A

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
Q

A LAN consists of….

A

all devices that are on the same broadcast domain

16
Q

Campus LAN

A

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

17
Q

Access switches

A

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

18
Q

Distribution switches

A

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

19
Q

Core switches

A

forward traffic between distribution switches

20
Q

Autonegotiation*

A

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

21
Q

10-BASE-T

A

CAT3 or better, two pair, 100m

22
Q

100-BASE-T

A

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

23
Q

1000BASE-T

A

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

24
Q

1000BASE-SX

A

Multimode fiber; 550 m

25
Q

1000BASE-LX

A

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

26
Q

1000BASE-LX

A

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

27
Q

IEEE autonegotiation rules

A

Use slowest speed

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

28
Q

Hub autonegotiation

A

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

29
Q

The switch CLI can be accessed by three methods…

A

Telnet, SSH, or the console

30
Q

Console requires…

A

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

31
Q

A difference b/n Telnet and SSH

A

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

32
Q

Switches can support up to __ simultaneous Telnet sessions

A

16

33
Q

SSH requires ____ for login

A

username and password

34
Q

Debug command

A

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

35
Q

Configuration commands

A

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

36
Q

Useful debug commands

A

no debug all
undebug all
debug

37
Q

RAM memory

A

Used for working storage (active configuration)

38
Q

ROM memory

A

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

39
Q

Flash memory

A

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

40
Q

NVRAM

A

stores the initial or startup configuration file

41
Q

reload command

A

erases RAM and copies start config into RAM

42
Q

erase startup-config or erase nvram

A

erases startup-configuration file

43
Q

terminal monitor (hint: debug)

A

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