Chapter 6 - Sheet1 Flashcards Preview

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Flashcards in Chapter 6 - Sheet1 Deck (53):
1

Switches enable ____ duplex between host and switch

full duples

2

The role of the ethernet switch

Forward ethernet frames to the right destination MAC address

3

3 goals of switches

Forward / Filter decisions, MAC Address learning, Loop avoidance

4

Switch's MAC Address Table AKA

Switching table, bridging table, content addressable memory (CAM) table

5

Inactivity Timer

For switch MAC address tables, a timer associated with each entry that counts time upward from
0 and is reset to 0 each time a switch receives a frame with the same MAC address. The entries
with the largest timers can be removed to make space for additional MAC address table entries if needed. Entries will high timers may be removed whether or not it's needed.

6

Unonwn Unicast Frames

An Ethernet frame whose destination MAC address is not listed in a switch’s MAC address
table, so the switch must flood the frame.

7

True/False:: Broadcast Frames are not forwarded by switches

FALSE. They are forwarded by switches

8

Protocol used to prevent layer 2 loops

Spanning Tree Protocol

9

STP causes each interface on a swtich to settle into which states?

Either blocking or fowarding

10

Blocking state of STP

Interface cannot forward or recieve data frames

11

Forwarding state of STP

Interface c an send and receive data frames.

12

3 internal processing methods for switches

Store-and-forward processing, cut-through, fragment-free

13

Store-and-forward processing

One of three internal processing options on some Cisco LAN switches in which the Ethernet
frame must be completely received before the switch can begin forwarding the first bit of the
frame.

14

Cut-through processing

frame is forwarded as soon as enough of the Ethernet header has been received for the switch to
make a forwarding decision, including forwarding the first bits of the frame before the whole
frame is received. Propagates errors, as bits are sent before FCS arrives

15

Fragment-free processing

first bits of
the frame can be forwarded before the entire frame is received, but not until the first 64 bytes of
the frame are received, in which case, in a well-designed LAN, collision fragments should not
occur as a result of this forwarding logic

16

ASIC

Application-specific integrated circuits. Switches make decisions based on ASIC chips (hardware) instead of software, like how bridges operate

17

Typical internal processing method for a switch

Store and forward. Improved latency from the other two methods is negligible, now that switches have ASIC chips and fasther uplilink connections and connections to hosts.

18

Features offered by a switch not offered by hubs or bridges

Microsegmentation, providing dedicated bandwidth to each host / multiple concurrent conversations between devices on different ports / ports connected to a singel device support full-duplex, doubling amt of bandwidth / rate adaption - devices can use different ethernet speeds to communicate

19

If a switch's address table lists the receiving interface as the interface connected to the destination MAC address, what does it do?

The switch filters the frame -- ignores it.

20

How can a collission still occur with a switch

If the host and switch are configured to half-duplex (instead of full-duplex) and they send and receive at the same time. So unlikely, but possible.

21

Collission Domain

set of network interface cards (NIC) 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.

22

Broadcast Domain

set of NICs for which a broadcast frame sent by one NIC is received
by all other NICs in the same broadcast domain

23

Effect of full-duplex on a switch

Doubling capacity -- a 100mbps connection becomes 200mbps.

24

Hub, Switch, Router: Which of these three allow for greater cabling distances?

Hub, Switch, Router

25

Hub, Switch, Router: Which of these three creates multiple collision domains?

Switch, Router

26

Hub, Switch, Router: Which of these three increases bandwidth?

Switch, Router

27

Hub, Switch, Router: Which of these three creates multiple broadcast domains?

Router

28

LAN, from the perspective of VLANs

A LAN consists of all devices in the same broadcast domain

29

campus lan

LAN created to support larger buildings

30

Autonegotiation

An IEEE standard mechanism (802.3u) with which two nodes can exchange messages for the
purpose of choosing to use the same Ethernet standards on both ends of the link, ensuring that the
link functions and functions well.

31

3 terms to describe the role of each switch in a campus LAN

access, distribution, core

32

Access Switch on a Campus LAN

Connect directly to end users, providing user device access to the LAN.

33

Distribution Switch on a Campus LAN

Provide a path through which the access switches can forward traffic to each other. Access switches connect to at least on distribution switch.

34

Core Switch on a Campus LAN

Forward traffic between distribution switches. Example: Campus with multiple buildings, each with several distribution switches, needs core switches to connect it all together.

35

3 most common types of Ethernet today

10Base-T, 100Base-T, 1000Base-T

36

Max length of 10Base-T, 100Base-T, 1000Base-T ethernet

100 meters

37

What organization defines ethernet cableing standards

EIA/TIA

38

What category of cabling does 10Base-T call for

Cat3 or higher (two pair)

39

What category of cabling does 100Base-T call for

Cat5 or higher (two pair)

40

What category of cabling does 1000Base-T call for

Cat5e or Cat 6 (four pair)

41

Max distance for 10Base-T

100 meters (328 ft)

42

Max distance for 100Base-T

100 meters (328 ft)

43

Max distance for 1000Base-T

100 meters (328 ft)

44

Max distance for 1000Base-SX

550 meters (1804.5 ft)

45

Max distance for 1000Base-LX

550 meters (1804.5 ft)

46

Max distance for 1000Base-LX Single Mode

5km (3.1 miles)

47

Media for 1000Base-SX

Multimode fiber

48

Media for 1000Base-LX, multimode

Multimode fiber

49

Media for 1000Base-LX, singlemode

9 micron single-mode fiber

50

IEEE rules if autonegotiation fails

Use your slowest supported speed. If speed is 10 or 100, use half-duplex. Otherwise, use full-duplex

51

Cisco rules if autonegotiation fails

Cisco devices can sense speed used by another node. Speed: Sense the speed. If that fails, use IEEE default. Duplex: Use IEE defaults

52

Duplex Mismatch

When a host's duplex is set to a value different from a connected host or switch .Example: Half duplex on a host, full duplex on a switch. This wil lresult in one client (host) using CSMA/CD and sensing collisions that don't exist. The link will be online, but perform poorly.

53

Autonegotiation response from hubs

They don't respond. Devices are forced to use IEEE defaults, often resulting in 10mbps and half-duplex speeds