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Cisco SG350 and Cisco C3750 for Yealink phones and voice vlan


i there,
is anybody out there with an official (or unofficial) documentation on how to priorize the traffic that comes from VOICE "Yealink" Phones on Cisco switches. We have little problems with the voice quality (Sometimes the voice gets really quiet)
We've enabled LLDP and "Voice vlan" on the ports of our edge switches (SG350)for our phones:

no snmp trap link-status
storm-control broadcast level 10
storm-control multicast level 10
port security max 2
port security mode max-addresses
port security discard trap 120
spanning-tree portfast
spanning-tree guard root
spanning-tree bpduguard enable
switchport mode trunk
switchport trunk native vlan 50
switchport trunk allowed vlan 50,333
no cdp enable


SwitchEdge01#show voice vlan
Administrate Voice VLAN state is auto-triggered
Operational Voice VLAN state is auto-enabled
Best Local Voice VLAN-ID is 333
Best Local VPT is 5 (default)
Best Local DSCP is 46 (default)
Agreed Voice VLAN is received from switch 44:3c:48:CE:8A:D7
Agreed Voice VLAN priority is 0 (active static source)
Agreed Voice VLAN-ID is 333
Agreed VPT is 5
Agreed DSCP is 46
Agreed Voice VLAN Last Change is 18-Jun-19 06:46:28

but there are still some issues. can one make sure that voice traffic is treated primary by the switch.
Furthermore we want to know how to configure the core switch (C3750) for these issues? The core switch is connected via a trunk with the edge switch.
I mean the edge switches with ports configured is just one part of the overall net design to priorize the voice traffic. But what about the core switchtes?
How do one prioritize the voice traffic when there is no phone connected directly?


1 Reply 1

Oleg Volkov

Is Your problem - voice quality or Your phones not put into voice vlan?


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