QoS principles and configuration examples

Aggregatable Networks:

Coexistence between voice and video traffic

Lack of bandwidth, end-to-end latency, jitter delay, packet loss

Addressing bandwidth scarcity:

1, Update bandwidth

2, forwarded as important traffic

3, 2-layer compression

4, compressed 3 laminar

Delay:

1, processing delay

2, Queue delay

3, serial delay (8bit converted to one byte)

4, Link delay

To resolve the delay:

1, Update bandwidth

2, forward the important traffic

3, compression 2-layer load

4, compressed IP header

Packet loss rate:

1,tail drops: Packets that exceed a certain depth queue are discarded

1,network Audit Network Audit

2,business Audit Business Audit

3,service levels required service level

QoS Model Classification:

1, best effort Model: no QoS service applied

2, Integration Service model: Before Application sender protocol, start signaling request service to Network

3, Differential service model: classifying traffic

Best Effort Service

Integration Services: guaranteed and predictable. End-to-end signaling protocol. Resource Reservation

1, providing multiple service levels 2

2, requires a signaling protocol

3, Resource Reservation protocol RSVP

4, using smart queues

Classification:

1, Guaranteed rate service

2, Load Control Service

Differentiated services: Classify services and have different service levels for different traffic

Differentiated Service Model:

Classifying traffic at the edge of the network

DSCP: Differential Service code point: based on each packet's

Per-hop behaviors: per-hop behavior

1, support various strategies

2, Service and application separation

3, back compatible with nodes that do not support differential services

4, Support incremental deployment

DSCP encoded Address:

IPv4 Baotou Format:

Versionlength ToSByte len ID offset ttl proto FCS Ipsa IPDA data

There are three bits of IP priority. Produces eight numeric values, the higher the value, the higher the priority, is only a token way.

DiffServ field: Using the TOS fields in IPv4

DSCP: 6bit using DiffServ field for the election of PHB (methods of forwarding and queuing)

Per-hop Behaviors

101110DSCP

Top three digits

000=default (Fifo,tail drop)be: No differential service model applied

101=expedited forwardingEF

001,010,011,or 100=assured forwardingAF

After three bits

000=class selector (IP precedence)CF

EF: Accelerated Forwarding 101110

1, guaranteed minimum forwarding rate

2, bandwidth is protected, priority forwarding

3, bandwidth allocation has a regulatory effect

Bits 5 to 7: ' 101 ' =5 uses the same as the IP TOS

Bits 3 to 4: ' One ' = NO DROP probability

Bits 2: ' 0 '

AF: Bandwidth Protection 100110

1, guaranteed minimum forwarding rate

DSCP VALUE RANGE:

Aaadd0

Four categories:

Af1,af2,af3,af4

ClassValue

AF1001 DD 0

af2010 DD 0

AF3011 DD 0

AF40 DD

The smaller the DD value, the greater the likelihood of being discarded.

The greater the AF value, the more resources you get

cf:xxx000 three bits are always 0, exactly as the IP tos

The greater the XXX gets the higher the bandwidth resources

QoS Mechanisms:

1, Category: DSCP, MQC

2, Mark

3, congestion management (queue mechanism): queue priority scheduling; Router out interface is in effect; FIFO/WFQ/CBWFQ/LLQ/PQ/CQ

4, congestion avoidance: avoid tail drop, wred

5, traffic control (speed limit) and shaping; The interface of the router is in effect (control), the outbound interface of the router is in effect (shaping)

6, Link validity: Shard, cross-transfer, compression

INPUT INTERFACE:

Classify, mark, policing

OUTPUT INTERFACE:

Congestion management, mark, congestion avoidance, shaping, policing, compressing, fragmentation and interleaving

QoS implementation methods:

1,qos CLI (emphasis)

2,auto QoS

3,sdm

4, Traditional QoS command line: no unified model

QOS CLI:

1, establish model definition traffic classification: class A, Class B, class C

Definition class Map,class MAP No serial number, case sensitive, default is match all

Match all: All conditions must match

Match any: At least one condition must be matched

Class-map can also be nested

2. Building module definition policy and specifying traffic classification to policy

Define policy MAP, case sensitive, call up to 256 class classes, can be nested

Policy Map yy

Class XX

bandwidth for a gigabit bandwidth

Class Class-default default traffic

Police 10000

Service-policy policy-name nested policy map

3, apply the policy to the interface

Define Service POLICY

Service-policy {Input|output} policy-map-name

Classification and marking in the use of link layers

802.1P is a high three bit (COS) in the 802.1Q tag

Mapping between the two-and three-layer markers

Rate-limit can be called directly under the interface

int s0/0

Rate-limit input|output ...

ACL that matches the interface MAC address

Access-list Rate-limit XX:XX:XX

Pq

PQ is the priority queue, when the PQ is congested, the sub-priority data is transmitted only when the high-priority data is all passed

However, you can limit the number of packets transferred per queue

Configuration case:

1, put the source IP 20.1.1.0/24 data into the queue high

Access-list Permit 20.1.1.0 0.0.0.255

Priority-list 1 Protocol IP High list 20

2, put the source IP 21.1.1.0/24 data into the queue medium

Access-list Permit 21.1.1.0 0.0.0.255

Priority-list 1 Protocol IP Medium List 21

3, put the port number of TCP 23 into the queue normal

Priority-list 1 Protocol IP normal TCP 23

4, the other data is put into the queue low

Priority-list 1 Default Low

5, limit the maximum number of packets per queue

Priority-list 1 queue-limit 400 300 200 100

6, applying PQ to interface

int s0/0

Priority-group 1

View PQ Parameters

Show Queueing priority

CQ

CQ has 1 to 16 total 16 queues, each of which can limit the total number of packets that can be transmitted, but real-time data cannot be guaranteed

When the network congestion, the first queue of data, when uploaded to the number of rated packets, and then pass the second queue of data

Queue No. 0 is a super-priority queue, and routers always send the data in queue No. 0 before processing packets from 1 to 16 queues

After configuring the 1 to 16th queue, the user can configure the ratio at which each queue can occupy the interface bandwidth at the same time, equivalent to the speed limit

Configuration case:

1, put the source IP 20.1.1.0/24 data into queue 1

Access-list Permit 20.1.1.0 0.0.0.255

Queue-list 1 Protocol IP 1 list 20

2, put the source IP 21.1.1.0/24 data into queue 2

Access-list Permit 21.1.1.0 0.0.0.255

Queue-list 1 Protocol IP 2 List 21

3, put the port number of TCP 23 into queue 3

Queue-list 1 Protocol IP 3 TCP 23

4, the rest of the data is put into queue 4

Queue-list 1 Default 4

5, limit the maximum number of bytes that each queue can pass. When the maximum number of bytes is reached, the next queue is transferred

Queue-list 1 Queue 1 byte-count 100

Queue-list 1 Queue 2 Byte-count 200

Queue-list 1 Queue 3 Byte-count 300

Queue-list 1 Queue 4 byte-count 400

6, limit the maximum number of packets that each queue can pass.

Queue-list 1 Queue 1 limit 10

Queue-list 1 Queue 2 limit 20

Queue-list 1 Queue 3 limit 30

Queue-list 1 Queue 4 limit 40

7, Application CQ to the interface

int s0/0

Custom-queue-list 1

View CQ Parameters

Show Queueing Custom

CBWFQ

The system follows the IP priority of each stream according to all available bandwidth of the interface, and gives a fair distribution to each stream

CBWFQ extends and optimizes wfq to divide specific bandwidth for specific traffic so that specific traffic can only be allocated from specific bandwidths of these partitions when allocating bandwidth

Configuration case:

1, matching the source address to 20.1.1.0/24 traffic through the ACL

Access-list Permit 20.1.1.0 0.0.0.255

2, match the source address to 20.1.1.0/24 traffic via Class-map

Class-map CLASS20

Match Access-group 10

3, bandwidth is divided for traffic 20.1.1.0/24 the source address

Policy-map Policy20

Class CLASS20

Bandwidth 1000

4, all other traffic is allocated from all remaining available bandwidth

Policy-map Policy20

Class Class-default

Bandwidth remaining percent use percent, you must set the bandwidth as a percentage before setting the

5, apply CBWFQ under the interface

int s0/0

Max-reserved-bandwidth the total available bandwidth of the modified interface

Service-policy Output Policy20

LLQ

LLQ for specific traffic to divide the specific bandwidth, the bandwidth allocated to a particular traffic is guaranteed, regardless of how busy the interface, traffic in the LLQ is able to transfer priority, but the bandwidth of these traffic can not exceed the allocated bandwidth, if more than, it is not related, These excess traffic is discarded only when it is congested.

Configuration case:

1, matching the source address to 10.1.1.0/24 traffic through the ACL

Access-list Permit 10.1.1.0 0.0.0.255

2, matching the source address to 20.1.1.0/24 traffic through the ACL

Access-list Permit 20.1.1.0 0.0.0.255

3, match the source address to 10.1.1.0/24 traffic via Class-map

Class-map net10

Match Access-group 10

4, match the source address to 20.1.1.0/24 traffic via Class-map

Class-map net20

Match Access-group 20

5, use LLQ to assign a Mbit to the source address of 10.1.1.0/24 traffic

Policy-map Band

Class Net10

Priority percentthe bandwidth allocated for traffic in LLQ, and the percentage after percent is the percentage of total interface bandwidth

6, use CBWFQ to allocate 50% of the remaining available bandwidth to traffic at the source address of 20.1.1.0/24

Policy-map Band

Class net20

Bandwidth remaining percentremaining percent is the proportion of the remaining bandwidth allocated from the distribution to LLQ

7, the total available bandwidth of the interface is 80Mbit

int s0/0

Max-reserved-bandwidth 80

8, Application queue to interface s0/0

int s/0

Service-policy Output Band

As long as there is CBWFQ, the direction can only be out

IP RTP

RTP-protected data flows can be wired before any traffic, even if LLQ and RTP occur simultaneously, RTP traffic takes precedence over LLQ delivery. Not all traffic is protected by RTP, only data with a UDP target port number of 16384 to 32767 can be protected and the port number range is freely defined

Congestion avoidance

Tail Drop

When an excuse is congested, the last packet that arrives is always discarded until there is no congestion

WRED

When the interface is congested, it always first guarantees the transfer of the high priority data, and discards the normal data.

Configuration:

1, enable IP priority-based wred under the interface

int s0/0

Random-detect

2, open the DSCP-based wred under the interface

int s0/0

Random-detect dscp-based

3, View wred

Show Queueing Random-detect

4, configure the wred under CBWFQ

Policy-map WWW

Class Class-default

Bandwidth 100000

Random-detect configured CBWFQ for all traffic via command bandwidth, and the IP priority-based wred is enabled through the command random-detect

Wred-explicit Congestion Notification

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QoS principles and configuration examples