Applying QoS Features to Ethernet Subinterfaces

kenny.lei

In general, choosing where to apply a policy depends on the QoS features that your policy is activating. An Ethernet subinterface supports the following:

• 
  Class-based policing - If you apply a policy with the police command to both the interface and the subinterface, only the subinterface policer is active for the traffic that matches the class. Refer to
  Traffic Policing
  for more information.
  
• 
  Class-based marking—refer to
  Classification Overview
  for more information.
  
• 
  Class-based shaping—refer to
  Configuring Class-Based Shaping
  for more information.
  
• 
  Class-based queueing—Queueing is a special case for Ethernet subinterfaces. See the remainder of this section for more information.
  

A router begins to queue packets when the number of packets that needs to be transmitted out an interface exceeds the output rate of that interface. The excess packets are then queued. A queueing method can be applied to packets waiting to be transmitted.
Cisco IOS logical interfaces do not inherently support a state of congestion and do not support the direct application of a service policy that applies a queueing method. Instead, you first need to apply shaping to the subinterface using either generic traffic shaping (GTS) or class-based shaping. Refer to
Policing and Shaping
for more information.
The router prints this log message when an Ethernet subinterface is configured with a service policy that applies queueing without shaping:
router(config)# interface ethernet0/0.1
router(config-subif)# service-policy output test
CBWFQ : Not supported on subinterfaces
Note that the same rule applies to a Gigabit Ethernet subinterface.
c7400(config)# interface gig0/0.1
c7400(config-subif)# service-policy ou
c7400(config-subif)# service-policy output outFE
  CBWFQ : Not supported on subinterfaces
In other words, you must configure a hierarchical policy with the shape command at the parent level. Use the bandwidth command for CBWFQ, or the priority command for Low Latency Queueing (LLQ) at lower levels. Class-based shaping limits the output rate and (we can assume) leads to a congested state on the logical subinterface. The subinterface than applies "backpressure," and Cisco IOS begins queueing the excess packets that are held by the shaper.
大致的意思就是说 不是所有CISCO 逻辑接口,都支持拥塞配置和直接应用 policy-map,解决方法是要在 shaping 下重新引用 policy-map
第一步、建access-list
ip access-list extended test-VC
  permit ip any host 1.1.1.1
ip access-list extended test-VG
   permit ip any host 1.1.1.2
第二步、建class-map 来 match 第一步的 access-list
class-map match-all test-VC
  match access-group name test-VC
class-map match-all test-VG
  match access-group name test-VG
第三步、建policy-map
policy-map test-for-shape-use
  class test-VC
   bandwidth 384
  class test-VG
   bandwidth 384
第四步、建shaping 来引用 第三步的 policy-map
Policy-map test-shape-768K
    class class-default
      shape average 768000
      service-policy test-for-shape-use
最后应用 shaping policy-map 到子接口
interface g0/3.3
service-policy output test-shape-768K


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