服务质量 (QoS) : QoS 拥塞管理(队列)

了解帧中继路由器接口上的队列

2015 年 8 月 28 日 - 机器翻译
其他版本: PDFpdf | 英语 (2015 年 4 月 22 日) | 反馈


目录


简介

此在serial interfaces的分层的排队体系结构配置与帧中继封装的本文探讨了。当配置与帧中继流量整形(FRTS),帧中继接口支持以下队列层:

  • PVC队列

  • 接口级别队列

先决条件

要求

本文读者应该熟悉以下知识:

使用的组件

用于本文的配置在一个Cisco 7200系列路由器捕获用以下硬件与软件:

  • PA-MC-4T1多信道T1端口适配器

  • Cisco IOS 软件版本12.2(6)

本文档中的信息都是基于特定实验室环境中的设备创建的。本文档中使用的所有设备最初均采用原始(默认)配置。如果您是在真实网络上操作,请确保您在使用任何命令前已经了解其潜在影响。

规则

有关文档规则的详细信息,请参阅 Cisco 技术提示规则

队列的层次

当FRTS应用对接口时,以下图说明两个队列的层次。应用FRTS和帧中继论坛实施协定(FRF.12)造成接口级别队列变成双重FIFO队列根据支持此排队技术的平台。两个队列包括高优先级队列运载VoIP和某些控制数据包和低优先级队列传送其他数据包。关于双重FIFO队列的更多信息,请参阅双重FIFO部分。

framerelayqueues.gif

帧中继接口支持接口队列以及PVC队列,当FRTS和PVC排队启用。如果PVC队列配置作为WFQ,每个PVC队列也支持一个分开的加权公平排队(WFQ)系统。

PVC 排队

帧中继和ATM接口可以支持多个虚拟电路(VC)。根据硬件,这些接口支持PVC队列,保证一拥塞的VC不浪费所有内存资源并且影响其他(非拥塞的) VC。

frame-relay traffic-shaping命令启用流量整形和PVC排队所有VC的在帧中继接口。PVC流量整形在个人VC提供对通信流的更多控制。流量整形与VC队列限制结合了单个VC的接口带宽消耗。没有任何shaping, VC能使用所有接口带宽和使其他VC挨饿。

如果不指定整形值,平均速率和突发流量大小的默认值应用。当对VC的流入负载超过整形值时,多余数据包在VC的信息包缓冲队列存储。一旦数据包缓冲,您能运用排队机制和有效控制从VC队列离队的数据包定货到接口队列。默认情况下, PVC队列以40数据包队列限制使用先来先服务的队列。请使用frame-relay holdq命令在映射组配置模式更改此值。交替地,您能应用低延迟队列(LLQ)或基于类别的加权公平队列(CBWFQ)使用用模块化QoS命令行界面(CLI) (MQC)的命令配置的服务质量(QoS)策略。另外,您能应用WFQ直接地在映射类别里面用fair queue命令。此命令在他们自己的子队列配置您的路由器根据流分类流量并且安置这些流。因此, fair queue命令创建一个WFQ系统每个VC。

PVC队列的详细的排队机制下述。

  1. 执行show frame-relay pvc 20命令。帧中继数据链路连接标识符(DLCI)由20识别。因为FRTS没有启用,不以下表示排队信息。

    Router# show frame PVC 20
     
    PVC Statistics for interface Serial6/0:0 (Frame Relay DTE)
      
    DLCI = 20, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial6/0:0.1
    
      input pkts 0              output pkts 0             in bytes 0
      out bytes 0               dropped pkts 0            in FECN pkts 0
      in BECN pkts 0            out FECN pkts 0           out BECN pkts 0
      in DE pkts 0              out DE pkts 0             out bcast pkts 0
      out bcast bytes 0
      
      PVC create time 00:00:38, last time PVC status changed 00:00:25
  2. 配置FRTS使用frame-relay traffic-shaping命令在接口配置模式在物理接口下。再执行show frame-relay PVC [dlci]命令

    Router# show frame-relay PVC 20
     
    PVC Statistics for interface Serial6/0:0 (Frame Relay DTE)
     
    DLCI = 20, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial6/0:0.1
     
      input pkts 0              output pkts 0           in bytes 0
      out bytes 0               dropped pkts 0          in FECN pkts 0
      in BECN pkts 0            out FECN pkts 0         out BECN pkts 0
      in DE pkts 0              out DE pkts 0
      out bcast pkts 0          out bcast bytes 0
      PVC create time 00:04:59, last time PVC status changed 00:04:46
      cir 56000     bc 7000    be 0       byte limit 875     interval 125 
      
    !--- Shaping parameters.
    
      mincir 28000       byte increment 875     Adaptive Shaping none
      pkts 0          bytes 0        pkts delayed 0         bytes delayed 0
      shaping inactive
      traffic shaping drops 0
      Queueing strategy: fifo               
    !--- Queue mechanism.
    
      Output queue 0/40, 0 drop, 0 dequeued 
    !--- Queue size.
    
    
  3. 默认情况下, PVC队列使用40数据包输出队列限度。请使用frame-relay holdq命令配置非默认值。

    Router(config)# map-class frame-relay shaping
    Router(config-map-class)# no frame-relay adaptive-shaping
    Router(config-map-class)# frame-relay holdq 50
       
    Router(config)# interface serial 6/0:0.1
    Router(config-subif)# frame-relay interface-dlci 20
    %PVC is already defined
    Router(config-fr-dlci)# class shaping
    Router(config-fr-dlci)# end
    Router# sh frame PVC 20
    
    PVC Statistics for interface Serial6/0:0 (Frame Relay DTE)
    
    DLCI = 20, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial6/0:0.1
    
       input pkts 0            output pkts 0            in bytes 0
       out bytes 0             dropped pkts 0           in FECN pkts 0
       in BECN pkts 0          out FECN pkts 0          out BECN pkts 0
       in DE pkts 0            out DE pkts 0
       out bcast pkts 0        out bcast bytes 0
       PVC create time 00:11:06, last time PVC status changed 00:10:53
       cir 56000    BC 7000      be 0         byte limit 875      interval 125
       mincir 28000    byte increment 875    Adaptive Shaping none
       pkts 0      bytes 0           pkts delayed 0          bytes delayed 0
       shaping inactive
       traffic shaping drops 0
       Queueing strategy: FIFO
       Output queue 0/50, 0 drop, 0 dequeued 
    !--- Queue size.
    
    
  4. PVC队列也支持CBWFQLLQ,使用服务策略和MQC的命令,您能配置。在QoS服务策略应用后,以下输出示例:在帧中继PVC捕获。

    Router(config)# class-map gold
    Router(config-cmap)# match ip dscp 46
    Router(config-cmap)# class-map silver
    Router(config-cmap)# match ip dscp 26
    Router(config-cmap)# policy-map sample
    Router(config-pmap)# class gold
    Router(config-pmap-c)#  priority 64
    Router(config-pmap-c)# class silver
    Router(config-pmap-c)#  bandwidth 32
    
    Router(config)# map-class frame-relay map1
    Router(config-map-class)# service-policy output sample
    
    Router(config-if)# frame-relay interface-dlci 20
    Router(config-fr-dlci)# class map1
    Router# show frame-relay PVC 20
      
    PVC Statistics for interface Serial6/0:0 (Frame Relay DTE)
     
    DLCI = 20, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial6/0:0.1
     
      input pkts 0             output pkts 0            in bytes 0
      out bytes 0              dropped pkts 0           in FECN pkts 0
      in BECN pkts 0           out FECN pkts 0          out BECN pkts 0
      in DE pkts 0             out DE pkts 0
      out bcast pkts 0         out bcast bytes 0
      PVC create time 00:12:50, last time PVC status changed 00:12:37
      cir 56000     bc 7000     be 0         byte limit 875    interval 125
      mincir 28000     byte increment 875   Adaptive Shaping none
      pkts 0      bytes 0   pkts delayed 0   bytes delayed 0
      shaping inactive
      traffic shaping drops 0
      service policy sample 
      
    Service-policy output: sample
    
       Class-map: gold (match-all)
         0 packets, 0 bytes
         5 minute offered rate 0 bps, drop rate 0 BPS
         Match: ip dscp 46
        Weighted Fair Queueing
          Strict Priority
          Output Queue: Conversation 24
          Bandwidth 64 (kbps) Burst 1600 (Bytes)
          (pkts matched/bytes matched) 0/0
          (total drops/bytes drops) 0/0
    	  
       Class-map: silver (match-all)
         0 packets, 0 bytes
         5 minute offered rate 0 BPS, drop rate 0 BPS
         Match: ip dscp 26
        Weighted Fair Queueing
          Output Queue: Conversation 25
          Bandwidth 32 (kbps) Max Threshold 64 (packets)
    !--- Queue information.
    
          (pkts matched/bytes matched) 
          (depth/total drops/no-buffer drops) 0/0/0
    
       Class-map: class-default (match-any)
         0 packets, 0 bytes
         5 minute offered rate 0 BPS, drop rate 0 BPS
         Match: any
        Output queue size 0/max total 600/drops 0 
    !--- Queue size.
    
    

最初, frame-relay holdq <size>映射种类命令用于配置大小仅FIFO流量整形队列。最大大小是512。在Cisco IOS软件版本12.2和从IOS软件版本12.2(4)此命令也影响在CBWFQ数据流整形队列的最大缓冲区,如启用由service-policy output map-class命令。最大大小当前是1024。默认,依然是不可更改,是40 FIFO的和600 CBWFQ的。

接口级排队

在帧中继帧在PVC队列后排队,他们离队对接口级别队列。从所有VC的流量穿过接口级别队列。

根据配置的功能,帧中继接口级别队列使用以下机制之一。

功能 默认排队机制
FRTS FIFO
FRF.12 双重 FIFO
PIPQ PIPQ

注意: PIPQ (PVC接口优先级排列)改写FIFO和双重FIFO。换句话说,如果启用FRF.12,接口排队策略依然是PIPQ。

FIFO 队列

以下步骤解释FRTS配置如何修改已应用排队机制对FIFO。

  1. 使用channel-group命令,创建信道化接口。

    Router(config)# controller t1 6/0
    Router(config-controller)# channel-group 0 ?
      timeslots  List of timeslots in the channel group
       
    Router(config-controller)# channel-group 0 timeslots ?
      <1-24> List of timeslots which comprise the channel
      
    Router(config-controller)# channel-group 0 timeslots 12
    
  2. 执行show interface serial 6/0:0命令并且确认T1接口使用默认“排队策略:加权公平”。首先,数据包被排列对在VC级别的一个花梢队列。它然后发送对接口队列。在这种情况下, WFQ将应用。

    Router# show interface serial 6/0:0
    Serial6/0:0 is up, line protocol is up (looped)
      Hardware is Multichannel T1
      MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
         reliability 253/255, txload 1/255, rxload 1/255
      Encapsulation HDLC, crc 16, Data non-inverted
      Keepalive set (10 sec)
      Last input 00:00:08, output 00:00:08, output hang never
      Last clearing of "show interface" counters never
      Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 
      Queueing strategy: weighted fair                           
    !--- Queue mechanism.
    
      Output queue: 0/1000/64/0 (size/max total/threshold/drops) 
    !--- Queue size.
    
         Conversations  0/1/16 (active/max active/max total)     
    !--- Queue information.
    
         Reserved Conversations 0/0 (allocated/max allocated)    
    !--- Queue information.
    
         Available Bandwidth 48 kilobits/sec                     
    !--- Queue information.
    
      5 minute input rate 0 bits/sec, 0 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         5 packets input, 924 bytes, 0 no buffer
         Received 0 broadcasts, 14 runts, 0 giants, 0 throttles
         14 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
         17 packets output, 2278 bytes, 0 underruns
         0 output errors, 0 collisions, 0 interface resets
         0 output buffer failures, 0 output buffers swapped out
         0 carrier transitions
      no alarm present
      Timeslot(s) Used:12, subrate: 64Kb/s, transmit delay is 0 flags 
    !--- Queue information.
    
    
  3. 当排队策略是WFQ时,您能使用show queueingshow queue命令确认。

    Router# show queueing interface serial 6/0:0
    Interface Serial6/0:0 queueing strategy: fair
      Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
      Queueing strategy: weighted fair
      Output queue: 0/1000/64/0 (size/max total/threshold/drops)
         Conversations  0/1/16 (active/max active/max total)
         Reserved Conversations 0/0 (allocated/max allocated)
         Available Bandwidth 48 kilobits/sec
    	 
    Router# show queue serial 6/0:0
      Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
      Queueing strategy: weighted fair
      Output queue: 0/1000/64/0 (size/max total/threshold/drops) 
         Conversations  0/1/16 (active/max active/max total)
         Reserved Conversations 0/0 (allocated/max allocated)
         Available Bandwidth 48 kilobits/sec
    
    
  4. 使用frame-relay traffic-shaping命令在接口配置模式,应用FRTS。

    Router(config)# interface serial 6/0:0
    Router(config-if)# frame-relay traffic-shaping
    
  5. 应用FRTS提示路由器改变在接口级别队列的排队策略到FIFO。

    Router# show interface serial 6/0:0
    Serial6/0:0 is up, line protocol is down (looped)
      Hardware is Multichannel T1
      MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
         reliability 255/255, txload 1/255, rxload 1/255
      Encapsulation FRAME-RELAY, crc 16, Data non-inverted
      Keepalive set (10 sec)
      LMI enq sent  13, LMI stat recvd 0, LMI upd recvd 0, DTE LMI down
      LMI enq recvd 19, LMI stat sent  0, LMI upd sent  0
      LMI DLCI 1023  LMI type is CISCO  frame relay DTE
      Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
      Last input 00:00:06, output 00:00:06, output hang never
      Last clearing of "show interface" counters 00:02:16
      Queueing strategy: FIFO      !--- queue mechanism
      Output queue 0/40, 0 drops; input queue 0/75, 0 drops
      5 minute input rate 0 bits/sec, 0 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         19 packets input, 249 bytes, 0 no buffer
         Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
         19 packets output, 249 bytes, 0 underruns 
         0 output errors, 0 collisions, 0 interface resets
         0 output buffer failures, 0 output buffers swapped out
         0 carrier transitions
      no alarm present
      Timeslot(s) Used:12, subrate: 64Kb/s, transmit delay is 0 flags
  6. 因为排队策略当前是FIFO, show queue and show queueing命令输出更改。

    Router# show queueing interface serial 6/0:0
    Interface Serial6/0:0 queueing strategy: none
    Router#
    
    Router# show queue serial 6/0:0
    'Show queue' not supported with FIFO queueing.

Cisco IOS软件版本12.2(4)T介绍针对接口拥塞的自适应帧中继流量整形功能,设计最小化延迟的导致的作用和丢包由接口拥塞。针对接口拥塞的自适应帧中继流量整形功能帮助保证丢包发生在VC队列。

当此新特性启用时,流量整形机制监控接口拥塞。当拥塞程度超过呼叫的配置值队列深度时,发送的速率所有PVC减少到最低的承诺信息速率(mincir)。当接口拥塞下降在队列深度下面,流量整形机制更改PVC的发送的速率回到承诺信息速率(CIR)。当有接口拥塞时,此进程保证PVC的mincir。

双重 FIFO

帧中继队列,在输出出现show interface serial命令中作为双重FIFO,使用两个优先级。高优先级队列处理语音数据包和控制数据包例如本地管理接口(LMI)。低优先级队列处理分片数据包(数据或非语音信息包)。

当您启用以下功能之一时,接口级排队机制自动地更改双倍FIFO :

  • FRF.12 分段--这用frame-relay fragment命令启用在映射组配置模式。数据包大于在frame-relay fragment命令指定的数据包大小首先被排列对WFQ子队列。他们然后离队并且被分段。在分段以后,第一分段传送。等待该VC的下个可用的传输时间,如整形算法取决于剩余分段。这时,小语音信息包和分段的数据数据包从其他PVC被插入。

  • 实时传输协议(RTP)优先级--最初,小数据包也分类如属于高优先级队列由于他们的大小。使用RTP优先级(VoIPoFR)功能, Cisco IOS软件版本12.0(6)T更改此行为。它预留仅语音和LMI控制数据包的高优先级队列。VoIPoFR通过匹配分类VoIP信息包在帧中继映射种类定义的RTP UDP端口范围。在此端口范围内的所有RTP流量排队对VC的一个优先级队列。另外,语音数据包努力去做到高优先级队列在接口级。其他数据包努力去做到非优先的队列在接口级。

    注意: 此功能假设, FRF.12配置。

请使用show interface命令查看两个队列的大小。下面的步骤显示双重FIFO队列并且描述如何更改队列大小。

  1. 执行show interface serial命令。高优先级队列使用两次是低优先级队列限制的大小的队列限制。

    Router# show interface serial 6/0:0
    Serial6/0:0 is up, line protocol is down
      Hardware is Multichannel T1
      MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
         reliability 255/255, txload 1/255, rxload 1/255 
      Encapsulation FRAME-RELAY, crc 16, Data non-inverted
      Keepalive set (10 sec)
      LMI enq sent  236, LMI stat recvd 0, LMI upd recvd 0, DTE LMI down
      LMI enq recvd 353, LMI stat sent  0, LMI upd sent  0
      LMI DLCI 1023  LMI type is CISCO  frame relay DTE
      Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
      Last input 00:00:02, output 00:00:02, output hang never
      Last clearing of "show interface" counters 00:39:22
      Queueing strategy: dual FIFO!
    --- Queue mechanism.
    
      Output queue: high size/max/dropped 0/256/0 
    !--- High-priority queue.
    
      Output queue 0/128, 0 drops; input queue 0/75, 0 drops 
    !--- Low-priority queue.
    
      5 minute input rate 0 bits/sec, 0 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         353 packets input, 4628 bytes, 0 no buffer
         Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
         353 packets output, 4628 bytes, 0 underruns
         0 output errors, 0 collisions, 0 interface resets
         0 output buffer failures, 0 output buffers swapped out
         0 carrier transitions
      no alarm present
      Timeslot(s) Used:12, subrate: 64Kb/s, transmit delay is 0 flags
  2. 请使用hold-queue {value} out命令更改接口队列大小。

    Router(config)# interface serial 6/0:0
    Router(config-if)# hold-queue ?
      <0-4096>   Queue length
      
    Router(config-if)# hold-queue 30 ?
      in   Input queue
      out  Output queue
      
    Router(config-if)# hold-queue 30 out
    
  3. 再执行show interface serial命令并且注意“输出队列”最大值如何更改。

    Router# show interface serial 6/0:0
    Serial6/0:0 is up, line protocol is up
      Hardware is Multichannel T1
      MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
         reliability 255/255, txload 1/255, rxload 1/255
      Encapsulation FRAME-RELAY, crc 16, Data non-inverted
      Keepalive set (10 sec)
      LMI enq sent  249, LMI stat recvd 0, LMI upd recvd 0, DTE LMI down
      LMI enq recvd 372, LMI stat sent   0, LMI upd sent  0
      LMI DLCI 1023   LMI type is CISCO    frame relay DTE 
      Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
      Last input 00:00:02, output 00:00:02, output hang never
      Last clearing of "show interface" counters 00:41:32
      Queueing strategy: dual FIFO                          
    !--- Queue mechanism.
    
      Output queue: high size/max/dropped 0/60/0            
    !--- High-priority queue.
    
      Output queue 0/30, 0 drops; input queue 0/75, 0 drops 
    !--- Low-priority queue.
    
      5 minute input rate 0 bits/sec, 0 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         372 packets input, 4877 bytes, 0 no buffer
         Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
         0 input errors, 0 CRC, 0 frame, 0 overrun,  0 ignored, 0 abort
         372 packets output, 4877 bytes, 0 underruns 
         0 output errors, 0 collisions, 0 interface resets
         0 output buffer failures, 0 output buffers swapped out
         0 carrier transitions
      no alarm present
      Timeslot(s) Used:12, subrate: 64Kb/s, transmit delay is 0 flags
    

PIPQ

帧中继PIPQ为方面独立的VC运载单个流量类型的配置设计在,例如语音或数据。这给您分配优先级值对每个PVC。PIPQ最小化序列化或排队延迟在接口级通过保证高优先级VC首先被服务。PIPQ通过解压缩DLCI和查寻在适当的PVC结构的优先级分类数据包。PIPQ机制不查看数据包内容。所以,它不做出根据数据包内容的决策。

请使用以下命令配置PIPQ。

  1. 启用PIPQ用frame-relay interface-queue priority命令在主接口。

    Router(config)# interface serial 6/0:0
    Router(config-if)# frame-relay interface-queue priority
    Router(config-if)# end
    
  2. 请使用show interface serial命令确认“排队策略:DLCI优先级”。此命令也显示丢包当前大小和数量每个队列的。

    Router# show interface serial 6/0:0
    Serial6/0:0 is up, line protocol is up
      Hardware is Multichannel T1
      MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
         reliability 255/255, txload 1/255, rxload 1/255 
      Encapsulation FRAME-RELAY, crc 16, Data non-inverted
      Keepalive set (10 sec)
      LMI enq sent  119, LMI stat recvd 0, LMI upd recvd 0, DTE LMI down
      LMI enq recvd 179, LMI stat sent  0, LMI upd sent  0
      LMI DLCI 1023 LMI type is CISCO  frame relay DTE 
      Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
      Last input 00:00:06, output 00:00:06, output hang never
      Last clearing of "show interface" counters 00:19:56
      Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
      Queueing strategy: DLCI priority 
    !--- Queue mechanism.
    
      Output queue (queue priority: size/max/drops):
         high: 0/20/0, medium: 0/40/0, normal: 0/60/0, low: 0/80/0  
    !--- Queue size.
    
      5 minute input rate 0 bits/sec, 0 packets/sec
      5 minute output rate 0 bits/sec, 0 packets/sec
         179 packets input, 2347 bytes, 0 no buffer
         Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
         0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
         179 packets output, 2347 bytes, 0 underruns
         0 output errors, 0 collisions, 0 interface resets
         0 output buffer failures, 0 output buffers swapped out
         0 carrier transitions
      no alarm present
      Timeslot(s) Used:12, subrate: 64Kb/s, transmit delay is 0 flags
  3. 使用frame-relay interface-queue priority命令{高,建立帧中继映射种类并且指定优先级到VC|介质|正常|低}。默认PVC优先级是正常。在同一优先级的所有PVC共享同一个FIFO优先级队列。运用映射类别对VC。在以下输出示例:中, PVC用DLCI号码21分配到高优先权接口队列。

    Router(config)# map-class frame-relay high_priority_class
    Router(config-map-class)# frame-relay interface-queue priority high
    Router(config-map-class)# exit
    
    Router(config)# interface serial 6/0:0.2 point
    Router(config-subif)# frame-relay interface-dlci 21
    Router(config-fr-dlci)# class ?
      WORD  map class name
       
    Router(config-fr-dlci)# class high_priority_class
    
  4. 请使用show frame-relay PVC [dlci]show queueing interface命令确认您的配置更改。

    Router# show frame PVC 21
    
    PVC Statistics for interface Serial6/0:0 (Frame Relay DTE)
    
    DLCI = 21, DLCI USAGE = LOCAL, PVC STATUS = INACTIVE, INTERFACE = Serial6/0:0.2
    
       input pkts 0            output pkts 0           in bytes 0
       out bytes 0             dropped pkts 0          in FECN pkts 0
       in BECN pkts 0          out FECN pkts 0         out BECN pkts 0
       in DE pkts 0            out DE pkts 0
       out bcast pkts 0        out bcast bytes 0
       PVC create time 00:00:17, last time PVC status changed 00:00:17
       cir 56000     BC 7000      be 0         byte limit 875    interval 125
       mincir 28000     byte increment 875   Adaptive Shaping none
       pkts 0         bytes 0         pkts delayed 0         bytes delayed 0
       shaping inactive
       traffic shaping drops 0
       Queueing strategy: FIFO
       Output queue 0/40, 0 drop, 0 dequeued 
       
    !--- Size of the PVC queue.
    
       priority high
       
    !--- All frames from this PVC are dequeued to the high-priority queue
    
       
    !--- at the interface.
    
    
    Router# show queueing interface serial 6/0:0
    Interface Serial6/0:0 queueing strategy: priority
     
    Output queue utilization (queue/count)
           high/13 medium/0 normal/162 low/0
    
  5. 随意地,请配置大小每个接口队列用以下命令。高、介质、正常和低优先级队列的默认容量分别为20, 40, 60和80数据包。要配置一个不同的值,请使用frame-relay interface-queue priority命令[<high limit><medium limit><normal limit><low limit>]在接口配置模式。

    一旦启用, PIPQ改写所有其他帧中继接口排队机制,包括双重FIFO。如果随后启用FRF.12或FRTS,接口级排队机制不会恢复双倍FIFO。另外,如果一个非默认异样的排队机制在接口,已经配置PIPQ不可能启用。如果WFQ是默认接口排队方法,它可以在WFQ面前启用。删除PIPQ配置更改接口级排队对默认或双倍FIFO,如果FRF.12启用。

    PIPQ应用严格优先级队列。如果流量不断地离队对高优先级队列,排队调度程序将安排高优先级队列,并且可能有效使低优先级队列挨饿。所以,请保重在分配PVC的到高优先级队列。

调整 TX 环

TX环是用于的不可优先化的FIFO缓冲区在发射前存储帧。帧中继接口使用由所有VC共享的单个TX环。默认情况下, TX环大小是更高速度的串行广域网接口的64数据包,包括PA-T3+, PA-MC-2T3+和PA-H。低速度WAN端口适配器自动地当前调低TX环对值2数据包。换句话说,接口驱动程序设置根据带宽数量的唯一默认TX环值。

队列 位置 排队方法 应用服务策略 调整命令
硬件队列或传输环路每个接口 端口适配器或网络模块 仅 FIFO tx-ring-limit
第3层队列每个VC 第 3 层处理器系统或接口缓冲区 FIFO、WFQ、CBWFQ或者LLQ 随排队方法变化:

注意: 不同于ATM接口例如PA-A3,帧中继接口使用单个传输环路接口。他们不建立每个VC的一个独立的环。

知道是重要的TX环是FIFO,并且不可以支持一备选排队机制。因此,调低TX环对值为2在低速接口有效移动大多数数据包缓冲向异样的排队机制和QoS服务策略应用的PVC队列。

下表列出7x00系列的串口适配器自动调的低传输环路。

端口适配器零件# TX环限速自动调整
高速串行端口适配器
PA-H和PA-2H
PA-E3和PA-T3
PA-T3+
多信道串口适配器
PA-MC-2T3+
PA-MC-2T1(=), PA-MC-4T1(=), PA-MC-8T1(=), PA-MC-8DSX1(=)
PA-MC-2E1/120(=), PA-MC-8E1/120(=)
PA-MC-T3, PA-MC-E3
PA-MC-8TE1+
PA-STM1
串口适配器
PA-4T, PA-4T+
PA-4E1G
PA-8T-V35, PA-8T-X21, PA-8T-232

当一个语音优化功能启用时,传输环路的大小自动地调低。另外,应用PIPQ造成传输环路自动地调低。

以下输出在运行Cisco IOS软件版本12.2(6)的7200系列路由器捕获。

7200-16# show controller serial 6/0:0
Interface Serial6/0:0
  f/w rev 1.2.3,   h/w rev 163, PMC freedm rev 1 idb = 0x6382B984
  ds = 0x62F87C18, plx_devbase=0x3F020000, pmc_devbase=0x3F000000 
    Enabled=TRUE, DSX1 linestate=0x0,
  Ds>tx_limited:1 Ds>tx_count:0 Ds>max_tx_count:20
  
  alarm present
  Timeslot(s) Used:1-24, subrate: 64Kb/s, transmit delay is 0 flags 
  Download delay = 0, Report delay = 0
  IDB type=0xC, status=0x84208080
  Pci shared memory = 0x4B16B200
  Plx mailbox addr  = 0x3F020040
  RxFree queue=0x4B2FA280, shadow=0x62F9FA70
  Rx freeq_wt=256, freeq_rd=256,  ready_wt=1, ready_rd=0
  TxFree queue=0x4B2FAAC0, shadow=0x62F8FA44
  TX freeq_wt=4099, freeq_rd=4099,  ready_wt=4, ready_rd=3 
  # of TxFree queue=4095
  Freedm FIFO (0x6292BF64), hp=0x6292C034 indx=26,  tp=0x6292CF5C indx=511
   reset_count=0 resurrect_count=0
  TX enqueued=0, throttled=0, unthrottled=0, started=10
  tx_limited=TRUE tx_queue_limit=2
  
!--- Note "tx_limited=TRUE" when PIPQ is enabled. The "tx_queue_limit" value

  
!--- describes the value of the transmit ring.
 
  
  7200-16(config)# interface serial 6/0:0
  7200-16(config-if)# no frame-relay interface-queue priority
  7200-16(config-if)# end
  7200-16# show controller serial 6/0:0
  Interface Serial6/0:0
    f/w rev 1.2.3,  h/w rev 163, PMC freedm rev 1 idb = 0x6382B984
    Ds = 0x62F87C18, plx_devbase=0x3F020000, pmc_devbase=0x3F000000
     Enabled=TRUE, DSX1 linestate=0x0,
    Ds>tx_limited:0 Ds>tx_count:0 Ds>max_tx_count:20
     alarm present
     Timeslot(s) Used:1-24, subrate: 64Kb/s, transmit delay is 0 flags
     Download delay = 0, Report delay = 0
     IDB type=0xC, status=0x84208080
     Pci shared memory = 0x4B16B200
     Plx mailbox addr  = 0x3F020040
     RxFree queue=0x4B2FA280, shadow=0x62F9FA70
     Rx freeq_wt=256, freeq_rd=256,  ready_wt=1, ready_rd=0
     TxFree queue=0x4B2FAAC0, shadow=0x62F8FA44
     TX freeq_wt=4099, freeq_rd=4099,  ready_wt=4, ready_rd=3 
     # of TxFree queue=4095
     Freedm FIFO (0x6292BF64), hp=0x6292C034 indx=26,  tp=0x6292CF5C indx=511
      reset_count=0 resurrect_count=0
     TX enqueued=0, throttled=0, unthrottled=0, started=11
     tx_limited=FALSE 
!--- Transmit ring value has changed.

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Document ID: 22304