1 Jul 2008 03:20
Re: new draft on IPv6 CPE router available for review
Hello, I have a comment on the transfered message by Wes, > From: Mikael Abrahamsson [mailto:swmike@...] > > > In section 5.3 I would definitely like a CPE to work without having a > WAN address (link local only). Actually, this does not work if a CPE use the strong host model implementation describing in RFC1122 or STD3 : Requirements for Internet Hosts - Communication Layers. > The rationale behind this is that we would like ISP routers have IPs > in a core IP-range (which will be protected from DDOS by ratelimiters or filters) > and have customers in their own IP space. > The handoff between distribution and CPE should be > done via something that is not reachable from the internet, ie the CPE > should never source packets from its WAN IP, instead it should source > packets destined to the internet from a loopback IP which it should > allocate to itself from DHCPv6-PD (it could also be a LAN interface IP). > So behavior would be "get link-local working, do DHCPv6-PD, allocate IP > to itself from PD range, then use THAT to provision itself further and > to communicate with everything". Originally, when we wrote RFC4241 (A Model of IPv6/IPv4 Dual Stack Internet Access Service) to start our IPv6/v4 dual stack native ADSL service, we also thought about same thing. So we can understand Mikael's will too. But now Microsoft Vista and Windows 2008 IPv6 implementation are based on(Continue reading)
> > I use that Vista is just as one example. The Strong Host Model is
> > defined in RFC1122 or STD3. That's a standard.
>
> But if it's a router (which I think is what is needed for a IPv6 CPE) then
> it should be able to act as one, and use loopback interfaces to source
> traffic.
Even in this case, some software which is going to send a packet to the network
from CPE, according to RFC3484 "Default Address Selection for IPv6",
there is a certain reason why the WAN I/F's IP address should be used as
its source address like follows.
---------------- from RFC3484 ----------------
It is RECOMMENDED that the candidate source addresses be the set of
unicast addresses assigned to the interface that will be used to send
to the destination. (The "outgoing" interface.) On routers, the
candidate set MAY include unicast addresses assigned to any interface
that forwards packets, subject to the restrictions described below.
Discussion: The Neighbor Discovery Redirect mechanism [14]
requires that routers verify that the source address of a packet
identifies a neighbor before generating a Redirect, so it is
advantageous for hosts to choose source addresses assigned to the
outgoing interface. Implementations that wish to support the use
of global source addresses assigned to a loopback interface should
behave as if the loopback interface originates and forwards the
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