Frame Relay For Voip Configuration Example - Cisco WS C4224V 8FXS - 200Mbps Ethernet Switch Software Configuration Manual

Configure Frame Relay for VoIP

Frame Relay for VoIP Configuration Example

Catalyst 4224 Access Gateway Switch Software Configuration Guide
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Shape the traffic—Use adaptive traffic shaping to slow the output rate based
•
on the backward explicit congestion notification (BECN). If the feedback
from the switch is ignored, packets (both data and voice) might be discarded.
Because the Frame Relay switch does not distinguish between voice and data
packets, voice packets could be discarded, which would result in a
deterioration of voice quality.
– Use RSVP, compressed RTP, reduced MTU size, and adaptive traffic
shaping based on BECN to hold the data rate to CIR.
– Use generic traffic shaping to obtain a low interpacket wait time. For
example, set committed burst (Bc) to 4000 to obtain an interpacket wait
time of 125 milliseconds.
In Cisco IOS Release 12.0 T, Frame Relay traffic shaping is not compatible with
RSVP. Cisco suggests one of the following workarounds:
Provision the Frame Relay permanent virtual circuits (PVC) to have the CIR
•
equal to the port speed.
Use generic traffic shaping with RSVP.
•
For Frame Relay, it is customary to configure a main interface and several
subinterfaces with one subinterface per PVC. The following example configures
a Frame Relay main interface and a subinterface so that voice and data traffic can
be successfully transported:
interface Serial0
mtu 300
no ip address
encapsulation frame-relay
no ip route-cache
no ip mroute-cache
fair-queue 64 256 1000
frame-relay ip rtp header-compression
interface Serial1 point-to-point
mtu 300
ip address 40.0.0.7 255.0.0.0
ip rsvp bandwidth 48 48
no ip route-cache
no ip mroute-cache
bandwidth 64
Chapter 6 Configuring VoIP
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