5-10
Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
956467
Chapter 5 QoS in a SOHO Virtual Private Network for IP Telephony
Solutions
Example 5-2
DSL QoS Configuration with a Third-party Modem
class-map match-any CBS-256kbps
match any
class-map match-all VOICE
match ip dscp EF
class-map match-all VOICE-CONTROL
match ip dscp AF31
!
policy-map WAN-EDGE
class VOICE
priority percent 33
class VOICE-CONTROL
bandwidth percent 2
class class-default
fair-queue
random-detect dscp-based
policy-map CBS-256kbps
class CBS-256kbps
bandwidth 256
shape peak 256000
service-policy WAN-EDGE
!
interface Ethernet1
ip address dhcp
service-policy out CBS-256kbps
In this example:
·
The concept of hierarchical service policies and classed-based policing is introduced. The
class-map match-any
and policy-map commands are used to provide class-based policing. The
symbolic name of "CBS-256kbps" represents class-based shaping (CBS) and the link speed.
Note
This configuration addresses most of the QoS requirements of a solution where you are not in direct
control of the DSL termination. However, LFI is not addressed, so large data packets could introduce
variability in delay and affect voice quality.
Application of QoS to Cable in a SOHO Environment
In SOHO VPN environments that use Cable 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.