队列概念介绍

王朝other·作者佚名  2008-05-19
窄屏简体版  字體: |||超大  

FIFO Queueing - first in first out, no change in packet order. Just like a line at the bank

There is a single queue per interface.

There is no change in response to traffic.

It is the default queueing on non serial interfaces that are as fast as a T1 or above.

Its not recommended for X.25, SDLC, or compressed ppp.

It's the fastest queueing method utilising the least router resources.

No Starvation

All traffic could fail if network is saturated

Weighted Fair Queueing -Cisco algorythim that chooses packet priority. Just like triage in an emergence room more immeadiate traffic moves to the front of the line

WFQ adapts to changes in traffic

There is a single queue per interface with Cisco automagically choosing packet order.

Default queueing method for everything else (ie. serial and below T1)

Slower than FIFO

Small packets and low volume traffic go to the head of the queue.

Uses stateful inspection and conversations to classify traffic

Bandwidth is shared for remaining traffic

Starvation improbable, Failures improbable

Priority Queueing -Administrative control

:

4 queues: High, Medium, Normal, Low

No change in response to traffic

Slower than Weighted fair.

Must be programmed

High queue is emptied before any other queues are considered

Starvation is possible and likely if you have a lot or bursty high priority traffic

Custom Queueing -Administrative control

16 queues (10 in IOS 11.1 or earlier

No change in response to traffic

Just a guess that it's the slowest method

May have from 1 to 16 queues

Must be programmed

Doesn't empty queue before servicing other queues

Services queue in chunks (byte count) in order so every queue gets visited

Default byte count is 1500 ( same as Ethernet MTU )

Starvation is not possible but all traffic can become lagged in a saturated network.

*FIFO

(config-if)#FIFO

*weighted fair

(config-if)#fair-queue{congestive-discard-threshold}

*Priority

(config-if)#priority-group group_number(1-16)

(config)#priority-list list-number protocol protocol-name {high | medium | normal | low} queue-keyword

keyword-value

list-number interface interface-type interface-number {high | medium | normal | low}

(config)#priority-list list-number default {high | medium | normal | low}

*optional commands

!command to change the max number of packets in each queue.

(config)#priority-list list-number queue-limit high-limit medium-limit normal-limit low-limit

!default 20 40 60 80

!queue-keyword values

fragmens--number of fragments

gt--port num

lt--port num

list---access list

tcp--port num

udp--port num

*Custom

(config-if)#custom-queue-list list_number(1-16)

(config)#queue-list list-number protocol protocol-name {high | medium | normal | low} queue-keyword keyword-value

(config)#queue-list list-number interface interface-type interface-number queue-number

(config)#queue-list list-number default queue-number

-optional commands

!specify the max number of packets for a particular queue (limit-number 0 - 32,767)

(config)#queue-list list-number queue queue-number limit limit-number

!if max number of packets are set too low you will drop the excess traffic!!!!

!default limit-number is 20

(config)#queue-list list-number queue queue-number byte-count byte-count-number

!default byte count is 1500

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航