QoS Configuration for VoIP on Cisco Networks

VoIP traffic is delay and jitter sensitive. QoS marks, queues, and prioritizes voice packets end-to-end.

QoS Design Model (3-tier)

TEXT

Access Layer: Mark traffic (DSCP EF for voice, AF41 for video)
Distribution: Queue and schedule
Core: Honor markings, minimal queuing

DSCP Markings

Traffic	DSCP	Queue
VoIP RTP	EF (46)	Priority
VoIP Signaling	CS3 (24)	Expedited
Video Conferencing	AF41 (34)	Bandwidth
Business Data	AF21 (18)	Normal
Best Effort	BE (0)	Default

Classification and Marking (Access Switch)

TEXT

! Match VoIP phones by DSCP (phones mark themselves)
class-map match-any VOICE
 match dscp ef
 match dscp cs3

class-map match-any VIDEO
 match dscp af41

policy-map EDGE-MARKING
 class VOICE
  set dscp ef
 class VIDEO
  set dscp af41
 class class-default
  set dscp default

interface GigabitEthernet1/0/1
 service-policy input EDGE-MARKING

Queuing Policy (Router WAN interface)

TEXT

policy-map WAN-QOS
 class VOICE
  priority percent 20        ! LLQ — strict priority
 class VIDEO
  bandwidth percent 20
 class SIGNALING
  bandwidth percent 5
 class class-default
  fair-queue
  bandwidth percent 55

interface Serial0/0/0
 bandwidth 10000
 service-policy output WAN-QOS

MikroTik QoS for VoIP

BASH

# Mark VoIP RTP packets
/ip firewall mangle add chain=forward src-port=10000-20000 protocol=udp action=mark-packet new-packet-mark=voip

# Queue tree priority
/queue tree add name=voip parent=global packet-mark=voip priority=1 max-limit=2M
/queue tree add name=data parent=global priority=8 max-limit=8M

Verification

TEXT

show policy-map interface Serial0/0/0
show queue Serial0/0/0
ping 192.168.10.50 repeat 1000 size 160

Target VoIP metrics: Latency <150ms, Jitter <30ms, Packet loss <1%.