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traffic disappeared after DSCP is applied with traffic policy as wrong understanding of qos

Publication Date:  2012-07-27 Views:  39 Downloads:  0
Issue Description
The detail network topology and diagnoise infomation please see the attachment. 
The brief topology infomation is as following:
            ----->    (   G 1/0/0.254  ) NE20 (G 1/0/0.408 )------>
After customer config traffic policy on outbound interface on G1/0/0.408,
some  packet with special dscp value will be always dropped.
Alarm Information
 Some packets will be dropped with special dscp value which can be seen in the attachment of  "scp test.doc". 
      
Handling Process
  
   After check the full configuration, we find the reason.
 RFC recommends code points for BE, EF, Afij and CSCP as below. CSCP is designed to be compatible with the IPv4 precedence model. 
l BE: DSCP=000000
l EF: DSCP=101110
l AFij code point: 
If j=1, the packet is marked with green color; if j=2, yellow color, and if j=3, red color.
However, the policy of defined in the configuration one outbound interface  is discard. So the packet will be dropped.
traffic behavior MLAN_CAR15.5Mbps_OUT
car cir 15872 cbs 12288 green pass yellow remark red discard  // For red, it is dropped even without configuration as it is default value. 
      
Root Cause
   1. Software bug.
   2.Configuration.
 
   3.Design fault.
      
Suggestions
    In fact, on NE20, there are two type QOS, if use "trust upstream", it will 
use self defined table which is different with differserv domain definition.
That's the reason I want share this case as not everybody know this even 
for R&D is also get the conclusion after test in lab. 

END