Subject: [Idr] New method for format of ExtCommunity then ExtCommunity can carry TOS of IP header and keep the ability for classifing route information

From: zhangzhifeng <[email-masked]>
Date: Thu, 10 Nov 2005 10:37:09 +0800

Dear all:

   If BGP Extended Community can map TOS value of IP header at the same time and keep the ability for classifing route 

information,the QoS policy based on BGP will be simple.

The format of ExtCommunity is as following:

Format of BGP ExtCommunity
 
   The BGP Extended Community is encoded as an eight octet quantity.
   We define the Format of the BGP Extended Community 
   as follows:
    
                - Type Field      : 1 octets
                - TOS Value Field : 1 octets
                - Value Field     : Remaining octets
  
        Type Field - the value mark the IANA regist information of BGP    
                     Extended Community and the format of the Value Field
 
        TOS Value Field - the value mark the TOS value that will be carried  
                          by the stream matched correlation networking 
                          information 
                         
        Value Field - the value mark the classified route imformatin 

      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Type Field    |TOS Value Field|          Value Field          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Value Field                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
The Type Field
 
   The size of Type Field for Regular types is 1 octet，as shown below：
 
             0 1 2 3 4 5 6 7
            +-+-+-+-+-+-+-+-+
            |I|T|  spare  |V|
            +-+-+-+-+-+-+-+-+

            I - IANA authority bit
            T - TOS bit
                Value 0: The TOS Value Field mark the default value 0
                value 1: The TOS Value Field mark the value which would
                         be remarked the IP packet 
            V - The value of this bit which can identify the format of
                the Value Field   
                 
                Value 0: The high-order two octets of the Value Field is
                         administrator Field, the remaining octets is
                         sub-administrator Field
 
                Value 1: The high-order four octets of the Value Field 
                         is administrator Field, the remaining octets is
                         sub-administrator Field

TOS Value Field
 
   The default value of TOS Value Field is 0. When the route information
   be imported into BGP, we can define the TOS Field value that the route 
   informatin should carried.
 
   According to defined DSCP value, we will define such BGP Extended 
   Community:

   ExtCommunity name    the high-order     DSCP classes     DSCP values
                        six bits of TOS
                        Value Field                        
   ExtCom-EF             101110               EF              101110
   ExtCom-AF41           100010               AF41            100010
   ExtCom-AF42           100100               AF42            100100
   ExtCom-AF43           100110               AF43            100110
   ExtCom-AF31           011010               AF31            011010
   ExtCom-AF32           011100               AF32            011100
   ExtCom-AF33           011110               AF33            011110
   ExtCom-AF21           010010               AF21            010010
   ExtCom-AF22           010100               AF22            010100
   ExtCom-AF23           010110               AF23            010110
   ExtCom-AF11           001010               AF11            001010
   ExtCom-AF12           001100               AF12            001100
   ExtCom-AF13           001110               AF13            001110
   ExtCom-BF             000000               BF              000000
 
   The remaining bits of TOS Value Field use 0 as value. 
 
Value Field   
   
   The Value Field used for identifing the route infomation which belong
   to different community. 
 
   We can set and change the value of the Value Field, and can't impact 
   the other Field.      

If you have any advice or suggestion, please contact me directly.
Thanks a lot!

zhangzhifeng
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