Tom, > 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".
wouldn't it then be simpler to require that a MUST be either 0 or 6? (or only 6). the discussion we've had earlier was that the benefit of being able to easily recognise the PSID in a port, made up for the lost 3K ports. which is what lead to an a=4. cheers, Ole _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
