10-11-2007 05:53 AM - edited 03-03-2019 07:07 PM
DSCP Value conversion to PHB Value mechanism and details required.
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10-12-2007 11:25 AM
Hello Guarav.
What zou are looking for is NOT mathematical. "AF" and "EF" is just a NAME defined in Standard. AF means Assured Forwarding, and EF means Expedited Forwarding. They could have named it "Very Important" and instead of EF we would use "VI"
So DSCP EF 46 is really DSCP 46. Standard defines how should numbers be used and what they are named. Please refer to the following documents:
AF: http://tools.ietf.org/html/rfc2597
EF: http://tools.ietf.org/html/rfc3246
DSCP: http://tools.ietf.org/html/rfc2474
Hope this helps.
Please rate all helpful posts
10-12-2007 11:40 AM
Hi,
It was detailed calculation:
AFXY, CSX and EF are just PHB codes for the corresponding DSCP in binary or decimal representation.
AFXY where X is the class (3bits)
Y is the priority (2bits)
AF calculation example: PHB codeAF33=011 11 0(binary)=30(decimal)
EF calculation example: PHB code EF =101 11 0(binary)=46(decimal)
101 is the precedence
11 is the class of service
0 remain 0
and so one for other values, I attached another more detailed table that resume all calculations of the DSCP binary and the equivalent decimal value from the precedence and class of service
10-11-2007 06:12 AM
10-11-2007 10:21 AM
Dear Parry,
Thats of great help but i am looking for mathematical calculas to do the conversion part.
i can do the DSCP to IP precedence but cld not achieve DSCP to PHB.
Can you help on this?
10-11-2007 09:36 PM
Hi matrin,
can you share the calculas of converting DSCP values to Assured Forwarding Classes and drop precedence.
DSCP 31 to AFxy.
How to convert 31 to xy? pls share the URL or method of doing it so.
10-12-2007 06:30 AM
Gaurav,
u may be looking for this:
http://www.cisco.com/en/US/products/ps6610/products_data_sheet0900aecd8031b36d.html
10-12-2007 07:29 AM
10-12-2007 09:46 AM
Hi abdel,
I am looking for methodology of calculating AFxy using given DSCP value instead of using table.
Like DSCP 46 means
a.) IP precedence =4
b.) TOS value = 184
c.) PHB = EF =101 but how have i derived 46 = EF?
Any possible calculation against this.
Please share.
10-12-2007 11:06 AM
10-12-2007 11:30 AM
Dear Sobair,
My apologies for writing IP precedence 4 instead of 5. But still my query hasn't been addressed.
How would i come to know that DSCP 36 is equal to AFxy?
how would i calculate that 36 = xy?
x= class service
y= drop precedence.
Hope you understand my question. please share any possible calculas.
10-12-2007 11:25 AM
Hello Guarav.
What zou are looking for is NOT mathematical. "AF" and "EF" is just a NAME defined in Standard. AF means Assured Forwarding, and EF means Expedited Forwarding. They could have named it "Very Important" and instead of EF we would use "VI"
So DSCP EF 46 is really DSCP 46. Standard defines how should numbers be used and what they are named. Please refer to the following documents:
AF: http://tools.ietf.org/html/rfc2597
EF: http://tools.ietf.org/html/rfc3246
DSCP: http://tools.ietf.org/html/rfc2474
Hope this helps.
Please rate all helpful posts
10-12-2007 11:40 AM
Hi,
It was detailed calculation:
AFXY, CSX and EF are just PHB codes for the corresponding DSCP in binary or decimal representation.
AFXY where X is the class (3bits)
Y is the priority (2bits)
AF calculation example: PHB codeAF33=011 11 0(binary)=30(decimal)
EF calculation example: PHB code EF =101 11 0(binary)=46(decimal)
101 is the precedence
11 is the class of service
0 remain 0
and so one for other values, I attached another more detailed table that resume all calculations of the DSCP binary and the equivalent decimal value from the precedence and class of service
10-12-2007 12:16 PM
Hi,
Great Explanation,
Deserve Full Rate.
Regards,
Mohamed Sobair
10-13-2007 07:50 AM
A little correction to Abdel's post: IP Precedence are not called CS0, CS1, and so forth. That's DSCP code. The following list describes the Codes (Names) of IP Precedence values in format "Binary (decimal) - Name":
000 (0) - Routine
001 (1) - Priority
010 (2) - Immediate
011 (3) - Flash
100 (4) - Flash Override
101 (5) - Critical
110 (6) - Internetwork Control
111 (7) - Network Control
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