5-15
Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
956467
Chapter 5 QoS in a SOHO Virtual Private Network for IP Telephony
Solutions
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 class-map VOICE, class-map VOICE-CONTROL, and service-policy WAN-EDGE
commands are responsible for providing LLQ/CBWFQ for preferential treatment of the VoIP bearer
and control traffic.
·
The policy-map CBS-256kbps and service-policy out CBS-256kbps commands are responsible
for shaping the traffic towards the SP link, protecting the VoIP traffic from unexpected loss and
queuing delays due to exceeding the SP guaranteed bandwidth.
Voice over ISDN
VoIP over ISDN is an acceptable solution for a SOHO solution.
illustrates how a SOHO
connected via ISDN would look from a device perspective.
Figure 5-12 VoIP over ISDN
This is not a solution where IPsec is encrypted through the Internet. It is a private network extension
using IDSN. Prior to IOS 12.2(7a), this was not a viable solution because the LLQ/CBWFQ Modular
QoS CLI service policies were not available for ISDN connections. With IOS 12.2(7a) and beyond, you
now have access to the full suite of tools required to guarantee voice quality over an ISDN connection.
illustrates the IOS configuration required to provide QoS in this environment.
Example 5-6
VoISDN QoS Configuration Example
class-map match-all VOICE
match ip dscp EF
class-map match-all VOICE-CONTROL
match ip dscp AF31
!
IP
Cisco 80x
To head
end
ISDN,
wireless, etc.
74929