Section 5.1.3 calls for the (optional) provisioning of a range of
excluded ports as part of a mapping rule. As my notes in Decemeber
hopefully made clear, the key issue is really whether system ports
(0-1023) are to be excluded or not. How many actually get excluded is a
function of block size, or of the sharing ratio if a = 0. The default
value of 4096 currently given in Section 5.1.3 is the block size implied
by an offset a = 4.
I would think an operator would not want to exclude any more ports than
necessary. Hence what needs to be provisioned is simply a Boolean
indication that system ports are to be excluded or not. If they are to
be excluded, then:
- for a = 0, as many PSIDs as necessary beginning with PSID = 0 MUST NOT
be used because the corresponding port ranges lie within the range 0-1023.
- for 1 <= a <= 6, the first block MUST NOT be used, because it contains
the system port range. The corresponding number of excluded ports
(including the system ports) ranges from 32768 for a = 1, down to
exactly 1024 for a = 6.
- a > 6, more than one block has to be excluded to make up the complete
range of 1024 ports.
The above bullets could be part of the explanation of the algorithm in
Section 5.1. Section 5.1.3 should change only by replacing "excluded
ports" by "whether system ports are excluded" and the default value of
that to "yes".
Tom Taylor
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