Hi Satoru-san, Thank you for your question. Answer below.
Le 14 sept. 2011 à 05:28, Satoru Matsushima a écrit : > Hi Remi-san, I have one question. > > On 2011/09/14, at 2:42, Rémi Després wrote: > >> >> Le 13 sept. 2011 à 18:08, <[email protected]> a écrit : >> >>> Hi Rémi, >>> >>> Thank you or your answer but my question was not on the CPE side but the >>> operations at the border router side. >> >> The point is that, with the new 4rd, an AFTR that sends an IPv4 packet to a >> CPE doesn't need to know the length of the CPE IPv6 prefix of that BR. >> This is a major difference with the old 4rd where this length was a rule >> parameter. (It is now a parameter only with the CPE-cascade option, to be >> ignored for this discussion.) >> >> As detailed in Figure 2, the BR includes in the subnet prefix of the IPv6 >> address L bits from the A+P port. >> This length L is 14 bits unless it has to be limited for this prefix to fit >> into 64 bits. > > Regarding the 4rd CEs are not cascaded, do you assume that the BR imply 64 > bits length for all CE's prefix length if the absence of CE IPv6 prefix > length configuration? The AFTR doesn't need to imply any CPE prefix length to build the right DST subnet prefix (64 bits). Let's take the example of sec. 6 (A), namely: +--------------------+--------------------+-------------------------+ | Domain IPv4 prefix | Domain IPv6 prefix | AFTR IPv6 subnet (e.g.) | +--------------------+--------------------+-------------------------+ | 192.32../12 | 2001:db0::/28 | 2001:db0:aaaa:aaaa::/64 | +--------------------+--------------------+-------------------------+ +-------------------------+--------------+------------------+-------+ | CPE IPv6 prefix | CPE IPv4 | Port-set bit | Nb of | | | address | pattern | ports | +-------------------------+--------------+------------------+-------+ | 2001:db1:1111:/48 | 192.33.17.17 | NA | 64K | | 2001:db2:2222:2000::/52 | 192.34.34.34 | yyyyxxxxxxx0100x | 3840 | +-------------------------+--------------+------------------+-------+ Let's assume that the AFTR has A+P packets to send to CPE IPv4 addresses 192.33.17.17 and 192.34.34.34 respectively, and both with dst port 0x4445. The L port bits to be included in subnet prefixes are then 2888::/15 (reversed order port bits 0-14). Destination subnet prefixes then comprise: - The Domain IPv6 prefix 2001:db0::/28 - 32 - 12 = 20 rightmost bits of IPv4 addresses, 1111:1000::/20 and 2222:2000::/20 respectively - 2888::/15 - One padding bit set to 0 They are: - 2001:db1:1111:2888::/64 - 2001:db2:2222:2888::/64 Each one starts with the CPE IPv6 prefix of the right dst CPE, which is enough to reach it. Hope it clarifies. Kind regards, RD _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
