hi Jacni,
在 2011年10月18日 上午11:54，Jacni Qin <[email protected]>写道：
>
>
> 1) list all mutually exclusive IPv4 networks to be involved in the residual
> deployment, i.e., Rule IPv4 prefixes;
> 2) calculate IPv6 prefix length for each Rule IPv4 prefix,
>
> For clarifications, you mean the "Rule IPv6 Prefix" length, right? since
> the length of Delegated Prefix should have been settled before this step.
>
>
sure. i meant the Rule IPv6 Prefix length. :)
there is still another issue, the MAX PSID. personally i like the algorithm
of making longest-match for the PSID. however, the position of the PSID is
somehow a problem. in the step 2) (or a little before), when you setting the
delegated prefix length, this length only covers the IPv4 suffix and the
PSID itself, right?
then if the length is, e.g., /64, and the PSID occupies the last 4 bits.
then the MAX PSID for a CE is put at 60 ~ 71 bits. this is fine with the
routing, which can get the encapsulated stuff to the right CE. however, it
may hurt the IID to some extent, for example, we have the PSID=0x4, while
for a certain packet, it contains destination port 0xe488, then the MAX PSID
= 0x488, and then the IID part for this packet towards the dst CE will be
not 200:5efe:: any more but
8800:5efe::
right? making the "u" bit destroyed, and the destination CE cannot identify
this is a packet for encapsulation or a packet for direct forwarding. it
also detroys the V-bit in the unified address format.
thus, may i understand that the planning should accommodate the MAX PSID in
the first 64 bits as well? if so, can we really satisfy the requirement R-1
at the Beijing interim, stating "Efficient bit representation. Address +
Port range in =/56", if the PSID is less than 4 bits?
sorry if i made anything, wrong. just try to understand the design, its
strength and limitations.
best,
maoke
>
> Cheers,
> Jacni
>
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