http://datatracker.ietf.org/doc/draft-murakami-softwire-4rd/?include_text=1
Section 4
The IPv4 prefix, IPv4 address or shared IPv4 address for use at a
customer site is created by extracting the IPv4 embedded address (EA-
bits) from the IPv6 prefix delegated to the site. …
A mapping rule consist of the following elements: a Domain IPv6
prefix and prefix length, a Domain 4rd prefix and prefix length, CE
IPv6 Prefix length, and a Domain IPv6 suffix and length. …
Section 4.1
The only remaining provisioning information the CE requires in order
to calculate the 4rd address and enable IPv6 connectivity is an IPv6
prefix for the CE. This CE IPv6 prefix is configured as part of
obtaining IPv6 Internet access (i.e., configured via SLAAC, DHCPv6,
DHCPv6 PD, or otherwise).
----------------------------------------------------------------------------------------
Q1. Per the above description, the EA-bits of CE IPv6 prefix sounds from
IAPrefix (option 26) of IA_PD (option 25) in DHCPv6. And the length of CE IPv6
prefix sounds a different one with the length of IAPrefix. Will the length of
CE IPv6 prefix + the length of Domain IPv6 suffix = (be equal to) the length of
IAPrefix?
----------------
Section 5.1.1
<----------- CE IPv6 prefix (max 128) -------------->
+-------------------------------+------------------------+
|Domain IPv6 prefix | EA-bits |
+-------------------------------+------------------------+
...
Figure 1: From a CE IPv6 Prefix to a CE 4rd Prefix
Section 5.1.4
...
Domain IPv6 suffix
|
+- - - - - - - -----------+- -
------+--|-+----------------------------------+
|Domain IPv6 prefix| EA-bits| ' | 0 |
+- - - - - - - -----------+- -
------+----+----------------------------------+
<- - - - - ------- max 64 ------------>
<- - - - - ----------------- CE IPv6 address (128) --------------------->
Figure 4: From 4rd Prefix to IPv6 address (shared IPv4 address case)
--------------------------------------------------------------------------------------
Q2. There is a conflict in Fig.1 with Fig.5. I guess there is a typo in Fig.1.
The max. length of CE IPv6 prefix sounds 64, right?
Q3. BTW, what is the design purpose of Domain IPv6 suffix?
Best Regards,
Leaf
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