Default/Recommended QoS Classification and Marking for Voice Packets

These are taken from the QoS SRND guide.

class-map match-all Voice
match ip dscp ef                          ! IP Phones mark Voice to EF (46)
class-map match-any Call Signaling
match ip dscp cs3                       ! Future Call-Signaling marking
match ip dscp af31                     ! IP Phones mark Call-Signaling (SCCP/MGCP)
policy-map WAN-EDGE
class Voice
priority percent 33                    ! Maximum recommended LLQ value
compress header ip rtp            ! Optional: Enables Class-Based cRTP
class Call Signaling
bandwidth percent 5                 ! BW guarantee for Call-Signaling
class class-default
fair-queue                                      ! All other data gets fair-queuing
Ok, now tell me why Auto QoS reserves 70% priority bandwidth for voice RTP class instead of 33% recommended? I’m still finding the answer…..

About Mijanur Rahman
Mijanur started blogging to save and share his study and research notes. A deep diver in technologies and loves to participate in technical brainstorming. Proud father of two wonderful daughters loves to spend time with them. He writes about the topics that people deal with every day mainly on technology arena. To get in touch contact him at

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