在Cisco 7500系列上采用分布式QoS的帧中继流量整形

简介

本文阐明了在具有通用接口处理器(VIP)的Cisco 7500系列路由器上和其他平台上将流量整形应用于帧中继接口之间的区别。其他平台包括Cisco 7200、3600和2600系列路由器。

先决条件

要求

本文档没有任何特定的要求。

使用的组件

本文档不限于特定的软件和硬件版本。

规则

有关文件规则的更多信息请参见“ Cisco技术提示规则”。

背景信息

自Cisco IOS®软件版本12.1(5)T起，服务质量(QoS)策略必须在VIP的分布式模式下运行；不再支持基于路由交换处理器(RSP)的QoS。因此，您必须使用模块化QoS命令行界面(MQC)的shape命令和其他命令，以便在Cisco 7500系列的VIP上为帧中继接口实施分布式流量整形(DTS)。DTS将通用流量整形(GTS)和帧中继流量整形（帧中继TS）相结合。 有关配置示例，请参阅配置分布式流量整形。

下表说明了如何配置帧中继TS，具体取决于平台：

^{1 dCEF} =分布式思科快速转发

注意：在Cisco 7500系列上，由于帧中继TS仅在非分布式模式下执行RSP，因此现在无法通过frame-relay traffic-shaping命令配置帧中继TS。使用dCEF和帧中继TS时，CEF“punt”邻接关系会导致RSP快速交换所有数据包，这对于最大转发性能而言是次优的。

配置步骤

使用以下步骤在基于VIP的帧中继接口上配置DTS:

1. 使用以下命令启用dCEF:

   router(config)# ip cef distributed
   

2. 确保已为分布式交换启用帧中继接口。

   router(config-if)# interface serial 8/0/0 
   router(config-if)# ip route-cache distributed
   
   router# show ip interface serial 8/0/0 
   Serial8/0/0 is up, line protocol is up 
     Internet address is 24.0.0.2/24 
     Broadcast address is 255.255.255.255 
    
   !--- Output suppressed.
    
     ICMP redirects are always sent 
     ICMP unreachables are always sent 
     ICMP mask replies are never sent 
     IP fast switching is enabled 
     IP fast switching on the same interface is disabled 
     IP Flow switching is disabled 
     IP CEF switching is enabled 
     IP Distributed switching is enabled 
     IP Fast switching turbo vector 
     IP CEF switching with tag imposition turbo vector 
     IP multicast fast switching is enabled 
     IP multicast distributed fast switching is disabled 
     IP route-cache flags are Fast, Distributed, CEF 
     Router Discovery is disabled 
     IP output packet accounting is disabled

3. 创建服务策略并将其应用于映射类。

   您可以实施以下策略之一：

   • 单级策略 — 将整形参数应用于虚电路(VC)流量

   • 分层策略 — 应用具有“父”级整形和“子”级排队的两级策略

     有关详细信息，请参阅将流量策略作为QoS策略（分层流量策略）示例。

   注意：虽然Cisco IOS软件版本12.1(2)T在Cisco 7500系列以外的平台上引入了对低延迟队列(LLQ)的支持，但VIP上的Cisco IOS软件版本12.1(5)T中引入了分布式LLQ(dLLQ)。分布式版本增强了此功能的性能。您可以为每个数据链路连接标识符(DLCI)配置唯一的服务策略。 您不需要使用映射类。您可以直接将service-policy命令应用到子接口或DLCI。但是，在映射类内配置dLLQ。

4. 使用以下命令验证服务策略的正确操作：

   • show policy-map interface

   • show interface shape

   • show vip full-qos

   使用分层策略配置DTS的示例

   ip cef distributed ! class-map 1 match <> !--- Define match-on criteria. class-map 2 match <> !--- Define match-on criteria. ! policy-map CBWFQ class 1 bandwidth <> !--- Define the value in kbps or percent. class 2 priority <> !--- Define the value in kbps or percent. ! policy-map SHAPE class class-default shape average service-policy CBWFQ ! int s0/0 encapsulation frame-relay ip route-cache distributed !--- Do not configure frame-relay traffic-shaping. ! int s0/0.1 point-to-point ip address a.b.c.d frame-relay interface-dlci xxx class cisco ! map-class frame-relay cisco service-policy output SHAPE

FRF.12 与 DTS

Cisco IOS软件版本12.1(5)T引入了分布式版本的帧中继分段FRF.12。将分布式FRF.12应用到帧中继接口时，必须定义映射类并在映射类下应用服务策略。如果尝试配置映射类并将服务策略直接应用到接口，则路由器会在启用日志记录控制台的情况下报告此错误消息：

Frame Relay fragmentation works with dTS only. 
Please remove traffic-shaping from the interface serial 1/0/0

本节中的配置和配置验证命令已在运行Cisco IOS软件版本12.2(5)T的Cisco 7500系列路由器（在RSP 8上）上进行测试。

注意：有关选择分段值的详细信息，请参阅具有服务质量(分段、流量整形、LLQ/IP RTP优先级)的帧中继VoIP。

interface Ethernet4/1/3 
 ip address 10.122.3.206 255.255.255.0 
! 
interface Serial5/0/0:0 
 no ip address 
 encapsulation frame-relay 
 load-interval 30 
 no fair-queue 

!--- Do not configure frame-relay traffic-shaping. 
! 
interface Serial5/0/0:0.1 point-to-point 
 ip address 10.1.1.2 255.255.255.0 
 frame-relay interface-dlci 16  
 class test 
 frame-relay ip rtp header-compression 
! 
map-class frame-relay test 
 no frame-relay adaptive-shaping 
 service-policy output llq-shape 
 frame-relay fragment 120 

!--- Apply the frame-relay fragment command to the !--- Frame Relay map class.

 access-list 101 permit udp any range 16384 32767 any  range 16384 32767

MS-7507-8A# show ip rtp head 
RTP/UDP/IP header compression statistics: 
DLCI 16 Link/Destination info: point-to-point dlci 
Interface Serial5/0/0:0: 
Distributed fast switched: 
4 seconds since line card sent last stats update 
Rcvd: 105475 total, 105472 compressed, 0 errors 
0 dropped, 0 buffer copies, 0 buffer failures 
Sent: 99451 total, 99447 compressed,  
3776208 bytes saved, 2187963 bytes sent 
2.72 efficiency improvement factor 
Connect: 256 rx slots, 256 tx slots,  
0 long searches, 3 misses 0 collisions, 0 negative cache hits 
99% hit ratio, five minute miss rate 0 misses/sec, 0 max 

MS-7507-8A# show policy-map  
Policy Map llq-shape 
 Class class-default 
  shape peak 256000 1024 1024 
  service-policy llq 
Policy Map llq 
 Class voip 
  priority percent 50 

MS-7507-8A# show policy-map interface s 5/0/0:0.1 
Serial5/0/0:0.1: DLCI 16 - 
Service-policy output: llq-shape 
  queue stats for all priority classes: 
  queue size 0, queue limit 32 
  packets output 147008, packet drops 0 
  tail/random drops 0, no buffer drops 0, other drops 0 
 Class-map: class-default (match-any) 
  148237 packets, 10393582 bytes 
  30 second offered rate 24000 bps, drop rate 0 bps 
  Match: any  
   queue size 0, queue limit 64 
   packets output 149563, packet drops 0 
   tail/random drops 0, no buffer drops 0, other drops 0 
  Shape: cir 256000, Bc 1024, Be 1024 
   lower bound cir 0, adapt to fecn 0 
   output bytes 6972057, shape rate 10000 bps 
Service-policy : llq 
  Class-map: voip (match-all) 
  146701 packets, 10325334 bytes 
  30 second offered rate 24000 bps, drop rate 0 bps 
  Match: access-group 101 
  Priority: 50% (128 kbps), burst bytes 3200, b/w  
  exceed drops: 0 
  Class-map: class-default (match-any) 
  1536 packets, 68248 bytes 
  30 second offered rate 0 bps, drop rate 0 bps 
  Match: any  
  queue size 0, queue limit 32 
  packets output 2555, packet drops 0 
  tail/random drops 0, no buffer drops 0, other drops 0 

MS-7507-8A# show frame pvc 16 
PVC Statistics for interface Serial5/0/0:0 (Frame Relay DTE) 
DLCI = 16, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial5/0/0:0.1 
input pkts 3036327   output pkts 199453 
in bytes 198958363  
out bytes 17271661   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 1071  out bcast bytes 371448  
5 minute input rate 0 bits/sec, 0 packets/sec 
5 minute output rate 35000 bits/sec, 50 packets/sec 
pvc create time 17:51:42, last time pvc status changed 17:50:53 
fragment type end-to-end fragment size 120  

MS-7507-8A# show interface shape 
Serial5/0/0:0 nobuffer drop 0 
Serial5/0/0:0.1(class 0): 
cir 256000, Bc 1024, Be 1024 
lower bound cir 0, adapt to fecn 0 
packets output 152104, bytes output 6985505 
queue limit 64, queue size 0, drops 0 
last clear = 16:58:59 ago, shape rate = 10000 bps

MS-7507-8A# show ip rtp head 
RTP/UDP/IP header compression statistics: 
DLCI 16 Link/Destination info: point-to-point dlci 
Interface Serial5/0/0:0: 
Distributed fast switched: 
4 seconds since line card sent last stats update 
Rcvd: 105475 total, 105472 compressed, 0 errors 
0 dropped, 0 buffer copies, 0 buffer failures 
Sent: 99451 total, 99447 compressed,  
3776208 bytes saved, 2187963 bytes sent 
2.72 efficiency improvement factor 
Connect: 256 rx slots, 256 tx slots,  
0 long searches, 3 misses 0 collisions, 0 negative cache hits 
99% hit ratio, five minute miss rate 0 misses/sec, 0 max 

MS-7507-8A# show policy-map  
Policy Map llq-shape 
 Class class-default 
  shape peak 256000 1024 1024 
  service-policy llq 
Policy Map llq 
 Class voip 
  priority percent 50 

MS-7507-8A# show policy-map interface s 5/0/0:0.1 
Serial5/0/0:0.1: DLCI 16 - 
Service-policy output: llq-shape 
  queue stats for all priority classes: 
  queue size 0, queue limit 32 
  packets output 147008, packet drops 0 
  tail/random drops 0, no buffer drops 0, other drops 0 
 Class-map: class-default (match-any) 
  148237 packets, 10393582 bytes 
  30 second offered rate 24000 bps, drop rate 0 bps 
  Match: any  
   queue size 0, queue limit 64 
   packets output 149563, packet drops 0 
   tail/random drops 0, no buffer drops 0, other drops 0 
  Shape: cir 256000, Bc 1024, Be 1024 
   lower bound cir 0, adapt to fecn 0 
   output bytes 6972057, shape rate 10000 bps 
Service-policy : llq 
  Class-map: voip (match-all) 
  146701 packets, 10325334 bytes 
  30 second offered rate 24000 bps, drop rate 0 bps 
  Match: access-group 101 
  Priority: 50% (128 kbps), burst bytes 3200, b/w  
  exceed drops: 0 
  Class-map: class-default (match-any) 
  1536 packets, 68248 bytes 
  30 second offered rate 0 bps, drop rate 0 bps 
  Match: any  
  queue size 0, queue limit 32 

  packets output 2555, packet drops 0 
  tail/random drops 0, no buffer drops 0, other drops 0 

MS-7507-8A# show frame pvc 16 
PVC Statistics for interface Serial5/0/0:0 (Frame Relay DTE) 
DLCI = 16, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial5/0/0:0.1 
input pkts 3036327   output pkts 199453 
in bytes 198958363  
out bytes 17271661   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 1071  out bcast bytes 371448  
5 minute input rate 0 bits/sec, 0 packets/sec 
5 minute output rate 35000 bits/sec, 50 packets/sec 
pvc create time 17:51:42, last time pvc status changed 17:50:53 
fragment type end-to-end fragment size 120 

MS-7507-8A# show interface shape 
Serial5/0/0:0 nobuffer drop 0 
Serial5/0/0:0.1(class 0): 
cir 256000, Bc 1024, Be 1024 
lower bound cir 0, adapt to fecn 0 
packets output 152104, bytes output 6985505 
queue limit 64, queue size 0, drops 0 
last clear = 16:58:59 ago, shape rate = 10000 bps

已知问题

如果仍使用Cisco IOS软件版本12.1E，则配置了帧中继封装的VIP接口可能会因总线错误而崩溃。如果在接口传递流量时应用服务策略，则会发生此崩溃。解决方法是在更新服务策略之前停止所有后台流量。或者，您可以升级到Cisco IOS软件版本12.2或更高版本。

有关详细信息，请参阅思科工具和资源页。

相关信息

• QoS 技术支持
• 技术支持和文档 - Cisco Systems