Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
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<strong>QoS</strong> <strong>Design</strong> Overview<br />
2-12<br />
<strong>Enterprise</strong> <strong>QoS</strong> <strong>Solution</strong> <strong>Reference</strong> <strong>Network</strong> <strong>Design</strong> <strong>Guide</strong><br />
Chapter 2 Campus <strong>QoS</strong> <strong>Design</strong><br />
Cisco 7905G—The 7905G is a basic IP phone that addresses the voice communication needs of a<br />
cubicle worker who conducts low to medium telephone traffic. The Cisco 7905G has only a single<br />
10BASE-T Ethernet port on the back of the phone; therefore, there is no hardware support to connect<br />
a PC to it.<br />
Cisco 7910G and 7910G+SW—The 7910G and 7910G+SW IP phones address the<br />
voice-communication needs associated with a reception area, lab, manufacturing floor, or employee<br />
with a minimal amount of telephone traffic. The only difference between the Cisco 7910G and the<br />
Cisco 7910G+SW is that the former has a single 10BASE-T Ethernet port (therefore, there is no<br />
hardware support to connect a PC to it), and the latter has two 10/100BASE-T Ethernet ports, which<br />
allow a PC to be connected to the IP phone.<br />
Cisco 7912G—The 7912G is a basic IP phone that addresses the voice-communication needs of a<br />
cubicle worker who conducts low to medium telephone traffic. The 7912G supports inline power<br />
and an integrated 10/100 Ethernet switch for connecting a PC. The switch used in the 7912G has the<br />
capability to mark CoS and DSCP of Voice and Call Signaling traffic that originates from the IP<br />
phone, but the Cisco 7912G does not have the capability to re-mark CoS values of PC-generated<br />
traffic.<br />
Cisco 7940G—The 7940G IP phone is suited best for an employee in a basic office cubicle<br />
environment—a transaction-type worker, for example—who conducts a medium amount of business<br />
by telephone. The 7940G supports inline power and has an integrated 10/100 Ethernet switch for<br />
connecting a PC.<br />
Cisco 7960G—The 7960G is designed to meet the communication needs of a profes¬sional worker<br />
in an enclosed office environment—an employee who experiences a high amount of phone traffic in<br />
the course of a business day. The 7960G supports inline power and has an integrated 10/100 Ethernet<br />
switch for connecting a PC.<br />
Cisco 7970G—The 7970G not only addresses the needs of the executive or major decision maker,<br />
but also brings network data and applications to users without PCs. This IP phone includes a backlit,<br />
high-resolution color touch-screen display. Cur¬rently, Cisco 7970G is the only Cisco IP phone that<br />
supports both Cisco prestandard Power over Ethernet (PoE) and the IEEE 802.3af PoE. The 7970G<br />
has an integrated 10/100 Ethernet switch for connecting a PC.<br />
All of the IP Phones listed above have the ability to mark 802.1Q/p CoS values for both VoIP and call<br />
signaling (default values are 5 and 3, respectively). Furthermore, they also have the ability to mark DSCP<br />
values for both VoIP and call signaling (current defaults are EF and AF31, respectively; future software<br />
releases will change these values to EF and CS3, respectively).<br />
IP Phone models 7902G, 7905G and 7910G lack the hardware to connecting a PC behind the Cisco IP<br />
Phone. All other IP Phone models listed above (except the 7912G) have the hardware support to connect<br />
a PC behind the IP Phone and also support 802.1Q/p CoS remarking of tagged packets that may originate<br />
from such PCs.<br />
The 10/100 Ethernet switch built into the 7912G does not have the support to re-mark CoS values that<br />
might have been set by a PC, as illustrated in Figure 2-7. This re-marking limitation represents a<br />
potential security hole for enterprises deploying these IP phones. However, this hole can be plugged, for<br />
the most part, with access-edge policers, as will be detailed in this chapter. It is important to note that if<br />
7912G IP phones are deployed to users that move locations, all user switch ports within the enterprise<br />
should have access-edge policers set on them to ensure mobility and security if a 7912G user moves the<br />
phones to another port.<br />
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