A simple summary of QoS

First, Service model for QOS:

1. Do your best

All data are equal, the tail drops are implemented when congestion occurs; forward --fifo

2. The Integration service model uses RSVP(Resource Reservation protocol)

Advantages :(1) can manage and control the network capital

(2) for each outgoing traffic can be deployed with different policies

(3) is based on each type of traffic definition

(4) based on QOSper stream, rather than per packet

(5) The established session is dynamic

3. Differentiated service Model EF,AF,CS,EB

Traffic classification can be implemented on a per-packet basis without the need for session maintenance of end to end traffic;

    using DSCP differentiate service coding points to prioritize packets, usually based on Span style= "Font-family:calibri;color:rgb (0,0,0); font-size:14px;" >per hop  behavior to classify;      0---

EF---Fast Forwarding------Voiceflow, maximum one-way delay not exceeding150ms, one-way jitter does not exceed30ms;----guarantee to forward;DSCPvalues are $;

af-- protection forwarding; AF1 af2 AF3 AF4

CS category Selector ---- with the IP priority is consistent;

be Do your best;

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DSCP value and PHB PHB AF-----DD Discard priority bit, 01 discard ratio 10

AF4 prior to AF3---AF2---AF1 ;

Second, queues:FIFO,PQ,CQ,WFQ,CBWFQ , LLQ

(1) FIFO: Advanced First Out

(2) PQ: Strict priority mechanism, high priority, medium priority, normal priority, low priority. High-priority queues must be processed before other queues are processed only when the high-priority queue is idle

(3) CQ: Custom queue, using a circular processing queue, regardless of priority, the average processing of each queue, each queue processing Bytes, if the size of a data more than a byte , the data must be fully processed before the next queue can be processed.

(4) WFQ: Weighted fair queue, different packets have different priority, priority high priority forwarding, priority high weight value is small, the weight value determines the service time, the default in the low-speed link has been enabled

(5) CBWFQ: Given different bandwidth guarantees based on different classifications, WFQ queue design for different classes, all non-system class bandwidth does not exceed the total bandwidth 75%

LLQ Low Latency queue: Mainly used for voice traffic, in order to ensure low latency and low jitter voice traffic is implemented, is a Pq+cbwfq approach, that is, according to the priority queue, according to the priority in the allocation of bandwidth ratio, As a safeguard, the bandwidth allocated at this time is strict (even in non-congested cases, the bandwidth of the guarantee is also unshared

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A simple summary of QoS