2013-02-11 23:51, Usman Latif <osma...@yahoo.com> : > Hi Remi, > > > > On 11/02/2013, at 9:13 PM, Rémi Després <despres.r...@laposte.net> >> ... >>> So if I understand it correctly, if a PE-CE link already has a /127 prefix >>> assigned to it- and we wanted to use the CE as a 4rd CE, we'll have to >>> assign an additional IPv6 prefix to the CE with 64-bit IIDs? >>> >>> Pls share little detail with me in a scenario where a SP already has /127 >>> with CEs and 4rd is needed from the CE >> >> According to RFC 6164, /127 prefixes are used ONLY on inter-router link. >> They cannot be used as customer-site IPv6 prefixes which, to comply with >> https://tools.ietf.org/html/rfc4291#section-2.5.1, MUST permit 64-bit IIDs. >> >> Each 4rd CE MUST therefore be delegated at least one IPv6 prefix having at >> most 64 bits (this doesn't depend on its WAN link having or not a /127). >> >> RD > > > Yes 6164 is only for inter-router links > I was under the impression that 4rd CE might use the WAN IPv6 address for > stateless tunnelling of IPv4 inside IPv6 > Maybe this was a misunderstanding(?)
In the 4rd specification, CE IPv6 prefixes are at most /64. See Figure 5 in particular: +----------+---+-+-+------+---+ +--------------+-+-+------+---+ |CE v6 prfx| 0 |V|0|v4 add|CNP| |BR IPv6 prefix|V|0|v4 add|CNP| +----------+-|-+-+-|+-----+---+ +--------------+-+-+------+---+ : =<64 : | :8:8: 32 :16 : : 64 :8:8: 32 :16 : | Padding to /64 RD > Or is it really upto the operator whether he wants to leverage the CE WAN > IPv6 prefix or the allocated IPv6 prefix routed to the CE site > If the CE WAN happens to be a /64 prefix, could the 4rd leverage that? > What is the recommendation there > > > Regards, > Usman > > >
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