Cisco 7500系列上使用分散式QoS的訊框中繼流量調節

簡介

本文檔說明了將流量整形應用到具有多功能介面處理器(VIP)的Cisco 7500系列路由器和其他平台上的幀中繼介面之間的區別。其他平台包括Cisco 7200、3600和2600系列路由器。

必要條件

需求

本文件沒有特定需求。

採用元件

本文件所述內容不限於特定軟體和硬體版本。

慣例

如需文件慣例的詳細資訊，請參閱思科技術提示慣例。

背景資訊

自Cisco IOS®軟體版本12.1(5)T起，服務品質(QoS)原則必須在VIP上以分散模式執行；不再支援基於路由交換處理器(RSP)的QoS。因此，您必須使用shape命令和模組化QoS命令列介面(MQC)的其他命令，才能為Cisco 7500系列上的VIP上的訊框中繼介面實作分散式流量調節(DTS)。DTS結合了通用流量調節(GTS)和訊框中繼流量調節（訊框中繼TS）。 如需範例設定，請參閱設定分散式流量調節。

下表說明了如何配置幀中繼TS，這取決於平台：

¹ dCEF =分散式Cisco Express Forwarding

注意：在Cisco 7500系列上，由於幀中繼TS僅在非分散式模式下執行RSP，因此現在阻止了通過frame-relay traffic-shaping命令配置幀中繼TS的功能。使用dCEF和幀中繼TS時，CEF「punt」鄰接會導致RSP快速交換所有資料包，這對於最大轉發效能而言不是最理想的。

配置步驟

使用以下步驟在基於VIP的幀中繼介面上配置DTS:

1. 使用以下命令啟用dCEF:

   router(config)# ip cef distributed
   

2. 確保幀中繼介面已啟用分散式交換。

   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. 建立服務策略並將其應用於對映類。

   您可以實施以下策略之一：

   • 單級策略 — 將整形引數應用於虛電路(VC)流量

   • 分層策略 — 應用兩級策略，在「父」級別進行整形並在「子」級別進行排隊

     有關詳細資訊，請參閱作為QoS策略的流量策略（分層流量策略）示例。

   註：Cisco IOS軟體版本12.1(2)T在Cisco 7500系列以外的平台上引入了對低延遲佇列(LLQ)的支援，而分散式LLQ(dLLQ)在VIP的Cisco IOS軟體版本12.1(5)T中引入。分散式版本增強了此功能的效能。您可以為每個資料鏈路連線識別符號(DLCI)配置唯一服務策略。 您無需使用對映類。您可以將service-policy命令直接應用於子介面或DLCI。但是，請在對映類內配置dLLQ。

4. 使用以下命令驗證服務策略的正確操作：

   • show policy-map interface

   • 顯示介面形狀

   • show vip full-qos

   使用分層策略的DTS配置示例

   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和DTS

Cisco IOS軟體版本12.1(5)T引入了訊框中繼分段FRF.12的分散式版本。將分散式FRF.12套用到訊框中繼介面時，您必須定義對映類並在對映類下套用服務原則。如果嘗試使用直接應用到介面的服務策略來配置對映類，則路由器會在啟用日誌記錄控制檯的情況下報告此錯誤消息：

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

本節中的配置和配置驗證命令已在Cisco 7500系列路由器上測試，該路由器在RSP 8上運行Cisco IOS軟體版本12.2(5)T。

註：有關選擇分段值的詳細資訊，請參閱具有服務品質(分段、流量調節、LLQ/IP RTP優先)的幀中繼上的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

已知問題

如果仍然使用Cisco IOS軟體版本12.1E，則配置有幀中繼封裝的VIP介面可能會因匯流排錯誤而崩潰。如果在介面傳遞流量時應用服務策略，就會發生此崩潰。解決方法是在更新服務策略之前停止所有後台流量。或者，您可以升級到Cisco IOS軟體版本12.2或更高版本。

如需詳細資訊，請參閱思科工具與資源頁面。

相關資訊

• QoS技術支援
• 技術支援與文件 - Cisco Systems