From: Boyan Krosnov (bkrosnov@lirex.bg)
Date: Sat Sep 20 2003 - 20:40:19 GMT-3
I just love posting links :)
-------------------
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_
reference_chapter09186a0080087f36.html#1017390
-----------------
Use the mask keyword to assign multiple IP precedences or MPLS
experimental field values to the same rate-limit access list. To
determine the mask value, perform the following steps:
------------------------------------------------------------------------
--------
Step 1 Decide which precedences you want to assign to this rate-limit
access list.
Step 2 Convert the precedences or MPLS experimental field values into
an 8-bit numbers with each bit corresponding to one value. For example,
an MPLS experimental field value of 0 corresponds to 00000001, 1
corresponds to 00000010, 6 corresponds to 01000000, and 7 corresponds to
10000000.
Step 3 Add the 8-bit numbers for the selected MPLS experimental field
values. For example, the mask for MPLS experimental field values 1 and 6
is 01000010.
Step 4 The command expects hexadecimal format. Convert the binary mask
into the corresponding hexadecimal number. For example, 01000010 becomes
42. This value is used in the access-list rate-limit command. Any
packets that have an MPLS experimental field value of 1 or 6 will match
this access list.
------------------------------------------------------------------------
--------
A mask of FF matches any precedence, and 00 does not match any
precedence.
-------------------------------------
the answer is "access-list rate-limit 1 mask 62" in my book.
BR,
Boyan Krosnov, CCIE#8701
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf Of Shawn Yang
> Sent: Sunday, September 21, 2003 2:11 AM
> To: ccielab@groupstudy.com
> Subject: access-list rate-limit with precedence mask
>
>
> Hi there,
>
> The question says:
>
> "
> configure CAR to police up to 10Mbps of inboud traffic
> with the precedence bit value from 1 to 5.
> "
>
>
> The solution has such an access-list created.
>
> access-list rate-limit 1 mask 31.
>
>
> My questions is why a mask of 31 correspond to values
> of 1-5?
>
> Could not find any detailed doc about how the mask
> should be derived in this case.
>
> Any help is appreciated!
>
> Shawn
>
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