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Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
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Chapter 5 QoS in a SOHO Virtual Private Network for IP Telephony
Solutions
Solutions
Now that you understand the problems that you need to solve (classification, scheduling, and
provisioning) and the tools that you can use to resolve those problems (LLQ/CBWFQ for classification
and scheduling, MLPPP with fragmentations and interleave for LFI), as well as an understanding of the
bandwidth requirements of VoIP in an IPsec environment, let's see how you apply these tools in the
following environments:
·
DSL
·
Cable
·
Other
Application of QoS to DSL in a SOHO Environment
In SOHO VPN environments that use DSL as the transport, there are three alternatives for deployment
(as illustrated in
). They are a one-box solution, a two-box solution, and a solution that uses
a third-party modem.
Figure 5-4
Typical DSL Deployments
There are two commonly used methods of delivering DSL to the SOHO, DSL over ATM (PPPoA) and
DSL over Ethernet (PPPoE). PPPoA implementations are the only DSL environments where you have
the complete set of features required to address all of the QoS requirements of the solution. In a PPPoE
environment (as of the writing of this paper), the full set of features required to address QoS from the
CPE, or last mile, perspective does not exist.
IP
IP
IP
Two-box
Third-party modem
Single-box
3rd-party
DSL modem
Cisco
806/1710
Cisco 827
PIX 501
DSL
Backbone
To head
end
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