From: Mark Miller (markmiller@alltel.net)
Date: Tue Apr 15 2003 - 22:04:21 GMT-3
Scott,
I'm not sure what you're asking here, but I'll give it my best shot at
answering this question.
DSCP values are categorized into four 'Assured forwarding Classes, and
one 'Expedited forwarding' class.
Class 1 = AF11, AF12, AF13 -- maps to ip prec. 1
Class 2 = AF 21, AF22,AF23 -- maps to ip prec 2
Class 3 = AF31, AF32, AF33 -- maps to ip prec 3
Class 4 = AF41, AF42, AF43 -- maps to ip prec 4
Expedited Forwarding (EF) -- maps to ip prec 5
The bit values for all of these assured forwarding (AF) can
be 'summarized' into a specific class (Class 1, Class2, etc.).
Now I'm not really sure about what you mean by "aggregate DSCP
levels", but if you look at these bit values, that's how these
different AF levels are put into different Classes.
For example....
AF21 010010
AF22 010100
AF23 010110
These AF values are in Class2. The first three bits are the same to
map to ip prec of 2, and are defined as the class selector code.....
010 =2, or Class 2. The last three bits define a prefered drop
preference. AF23 will get dropped before AF22, etc.
I may be WAY OFF here, but if I were asked to "aggregate" some
dscp values, I would guess you were being asked to specify what
class (Class 1, Class 2, etc) to put all of them in.
In your example, however, you could not put these in one class
because a value of 32 moves into the Class 4 space.
I hope this helps. If I'm way off in left field from what you were asking
please disregard and have a nice day.
Mark :-)
----- Original Message -----
From: "Scott M. Livingston" <scottl@sprinthosting.net>
To: <ccielab@groupstudy.com>
Sent: Tuesday, April 15, 2003 4:20 PM
Subject: Aggregating DSCP values
> I am going to keep digging at it, but I am stumped now. I believe I
> understand how to aggregate precedence levels, but I am clueless on how
> to aggregate DSCP values. Is there a way to do this? I have browsed some
> url's and looked at the two RFC's, but nothing is jumping out at me yet.
> Guess I have to dig a little deeper.
>
> Let us say there is a task to group DSCP 28 through 32. How would one do
> this without having to create 5 ACL's for each value?
>
> Thank You,
> scott
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