CCNA/CCNP preparation notes

by Andreas Ryf

FIFO

First In First Out

standard behaviour of switches & routers without any different configuration.

Priority Queuing

4 categories/Queues:

High priority

Medium priority

Normal priority

Low priority

Custom Queuing

Bandwidth guaranteed, but no delay guarantee.

Round robin procedure

no queue gets forgotten

Not recommended for VoIP as no delay guarantee.

16 queues

Weighted Fair Queuing

No delay guarantee

No bandwidth guarantee

uses IP preceedence markings

small packets are handeled with priority

Not recommended for VoIP

Class Based Weighted Fair Queuing CBWFQ

256 classes

No delay guarantee

Bandwidth guaranteed

Low Latency Queuing LLQ

Priority queuing & CBWFQ combined

One priority queue

Rest is queued by CBWFQ

Priority queue is "policed", which limits clearly it's bandwidth, in order not to starve the other traffic.

Delay guarantee for priority queue only

Bandwidth guaranteed

Priority queue should not exceed 33% of total bandwidth

Total guaranteed bandwidths should not exceed 75% of total bandwidth

You are here: Home-ONT-Queuing

Previous Topic: Cisco AutoQoS Next Topic: Congestion