JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?=
<[EMAIL PROTECTED]> writes:
> I admit that DHCPv6 only with information resources is also simple.
> However, in order to apply DHCPv6 in the real network, we'll need
> - a DHCPv6 relay agent (basically) in every subnet, or
Not really a problem, as all routers today have relay agent
support. In DHCPv4, the issue is configuring them. With DHCPv6, they
don't need configuring, they use multicast to find the servers.
> - multicast routing when we use a well-known multicast addresses for
> DHCP servers
I'd like the WG to think about this point very carefully. In hallway
discussions in SLC, it was asserted to me that the existance of IP
multicast, in home or enterprise networks (as opposed to WANs and
backbones) was not something that IPv6 could depend on. For example, I
was told by one individual that SLP wasn't a viable solution for
service discovery because it relies in multicast. Hence, DNS Discovery
couldn't just use SLP.
The implications of this assertion are very significant. If site-wide
multicast cannot be assumed, it means basic infrastrcuture protocols
(like DHCP, SLP, etc.), *where* they depend on multicast, won't work,
and we may need to invent protocols (or extensions) that don't have
these shortcomings.
On the other hand, extending an existing protocol or inventing a new
one also has a cost associated with it - perhaps higher than the cost
of getting multicast into a state where it can be relied upon.
So, I'd like to ask the WG:
1) Do people think that the existance of multicast within a site
(e.g., home, enterprise, etc.) can be assumed?
Note: I'm assuming link-local multicast will always work, the
question is whether wider scope (beyond neighboring routers)
multicast is available.
2) If the answer is "can't assume multicast is present", what should
be done about it. e.g.,
- What are the barriers that are preventing multicast from being an
assumed part of the infrastructure? What is needed to remove
those barriers?
- Which infrastructure protocols does IPv6 rely on that assume the
existance of multicast, and how are they limited if multicast is
not available?
Thomas
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