Chapter 3 - Understanding Cisco IP Phones

Question 1

802.3af

Answer 1

Power over Ethernet; Industry-standard method of supplying power over an Ethernet cable to attached devices

Question 2

802.3at

Answer 2

A PoE standard that supports devices requiring more power (up to 25.5 W)

Question 3

Power over Ethernet (PoE)

Answer 3

The capability to send electricity over an Ethernet cable to power a connected device

Question 4

Cisco Inline Power

Answer 4

Cisco-proprietary, prestandard method of supplying power over an Ethernet cable to attached devices

Question 5

Cisco Discovery Protocol (CDP)

Answer 5

Protocol that allows Cisco devices to discover other, directly attached Cisco devices. Switches also use CDP to send voice VLAN information to attached IP phones

Question 6

Virtual LAN (VLAN)

Answer 6

A configuration used to break a switch into multiple broadcast domains

Question 7

Trunking

Answer 7

Allows VLAN information to be passed between switches

Question 8

802.1Q

Answer 8

An industry-standard trunking protocol that allows traffic for multiple VLANS to be sent between switches

Question 9

Dynamic Trunking Protocol (DTP)

Answer 9

Allows switches to dynamically negotiate trunk links

Question 10

Skinny Client Control Protocol (SCCP)

Answer 10

Cisco-proprietary voice-signaling protocol used to control Cisco IP phones

Question 11

Session Initiation Protocol (SIP)

Answer 11

Voice-signaling protocol created by the IETF as a light-weight alternative to H.323

Question 12

Network Time Protocol (NTP)

Answer 12

Synchronizes the clock of a network device to a more accurate NTP server.

Question 13

QoS

Answer 13

Quality of service is the ability of the network to provide better or special service to a set of users and applications at the expense of other users and applications.

Question 14

Link Efficiency

Answer 14

focuses on delivering network traffic in the most efficient way

Question 15

Classification

Answer 15

The first device that receives a packet identifies it using tools such as access-lists, incoming interfaces, or deep packet inspection.

Question 16

Marking

Answer 16

After a packet is identified, it is marked in Layer 2 or 3 so that switches or routers can read it. Devices then route the packet based on the marking.

Question 17

Policing

Answer 17

Limits the amount of bandwidth certain network traffic can use

Question 18

queuing

Answer 18

x

Question 19

LLQ

Answer 19

Low Latency Queuing - Same as CBWFQ but adds a priority queuing component. Guarantees bandwidth for selected traffic plus guarantees it the first bandwidth

Question 20

Priority Queuing

Answer 20

Guarantees first bandwdith

Question 21

WFQ

Answer 21

Weighted Fair Queuing - tries to balance available bandwidth among all senders evenly - often the default on Cisco routers

Question 22

CBWFQ

Answer 22

Class-based Weighted Fair Queuing - allows you to specify guaranteed amounts of bandwidth for your various classes of traffic

Question 23

Fragmentation

Answer 23

Chop large packets into smaller pieces before they are sent

Question 24

Interleaving

Answer 24

Send critical VOIP traffic in between fragmented data traffic

Question 25

DSCP

Answer 25

A 6-bit bit-pattern (called the Differentiated Services Code Point [DSCP]) in the IPv4 ToS Octet or the IPv6 Traffic Class Octet is used as shown in Figures 1, 2, and 3. Figure 1. IPv4 and IPv6 Headers. Figure 2. The Original IPv4 ToS Byte.

Question 26

AutoQoS

Answer 26

Cisco QOS implementation that allows you to enable a variety of QoS mechanisms with very little knowledge of QOS. Deploys a template QoS configuration in line with Cisco QoS best practices.