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QOS CONFIGURATION
Only make adjustments if you understand how these features work.
Diffserv Configuration
DiffServ Code Point (DSCP) or ToS establishes the priority of voice packets. Compatible routers apply the
DSCP for packet priority, handling higher priority packets first. However, at congested routers, higher
priority packets are discarded first. Thus, a median value for DSCP is recommended.
IEEE 802.1Q
The VLAN tag defines the priority for Ethernet frames and the VLAN ID based on IEEE 802.1p/q. If using
with FortiVoice phone systems, 802.1p/q tagging is not currently supported. The phone PC and LAN (voice)
ports use separate VLAN tags. With a VLAN ID assigned, only frames with the ID are accepted and frames
sent from the phone include the LAN port ID and priority. In addition, the PC, LAN ports and the default
gateway must be assigned to employ the VLAN tags for proper operation.
Jitter Buffer Configuration
A jitter buffer stores incoming packets to allow for re-sequencing of packets received out of order. The jitter
buffer configuration controls the size of the buffer used. The minimum, normal and maximum delays
expected can be changed. Using larger values produce less packet loss as the phone waits longer to receive
packets before processing. Note that large values may delay voice packet processing and smaller values may
produce more packet loss but quicker voice packet processing. We recommend you use the default settings.
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Troubleshooting
