Quality of Service

What this topic solves

Classification, marking, DSCP, policing, shaping, queuing, scheduling and congestion management.

Follow state and packet path

Separate IP connectivity from the service itself. Capture the transaction and validate state, timers, relay/proxy functions and security policy.

Input → classification/state → decision → table → next-hop/output → counters

Design before configuration

• Define the failure domain and expected convergence behavior.
• Document addressing, identifiers, timers, MTU and policy boundaries.
• Prefer explicit, observable state over assumptions.
• Plan rollback and out-of-band access before risky changes.

Commands and verification

Command syntax varies by platform and software release. The examples below come from the existing portal content and must be validated against the target platform documentation before production use.

class-map match-any VOZ
 match dscp ef

policy-map WAN-OUT
 class VOZ
  priority percent 10
 class class-default
  fair-queue

interface GigabitEthernet0/0
 service-policy output WAN-OUT

show policy-map interface
show class-map
show policy-map

/ip/firewall/mangle/print detail stats
/queue/simple/print detail stats
/queue/tree/print detail stats
/queue/type/print detail
/ip/firewall/connection/print

# Mangle pode marcar connection/packet/routing
# e também modificar DSCP conforme política.

Evidence-driven workflow

1. Define source, destination, time window and exact symptom.
2. Establish the expected healthy state and compare it with the observed state.
3. Inspect counters, tables, logs and packet captures before resets.
4. Test one hypothesis at a time and prefer reversible changes.
5. Repeat the original test after correction and check side effects.

Standards and RFCs applicable to the technology

Use the current standard/RFC and the documentation for the exact software release being operated. Vendor syntax is an implementation detail; protocol behavior should be understood independently.

Prove the behavior in a controlled topology

Build the smallest topology that reproduces the mechanism, capture control and data traffic, introduce one deliberate failure and diagnose it before applying the fix.

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