Le 20/08/2010 20:47, Thomas Narten a écrit :
Sri Gundavelli<sgund...@cisco.com> writes:
Couple of comments on Section 9.0 (Mobility):
draft-ietf-6man-node-req-bis-05
1.) When Mobile IPv6 was designed, one important feature that made
into the protocol is the support for Route Optimization. The
ability for a mobile node to provide the information on the direct
(non-anchor or non-triangular) path to a Correspondent Node. This
was not possible in Mobile IPv4, as any change requirement to IPv4
did not make much sense.
Actually, this explanation is not consistent with history. RO was
not added to MIP4 because there was no customer for the work. MIP has
been implemented and deployed in IPv4. But those using it had no
need for and didn't seem to have a business case for RO. There was
an ID for RO for MIP4 at one time, but the WG abandoned the draft
when it became clear no one had interest in actually deploying it.
I think this point is very much worth noting. We can jump up and
down all day and say some feature is really cool and beneficial, but
what really matters is whether someone will actually deploy and use
it, based on the value they see.
Also, deploying MIP is much more complicated than deploying other
IPv6 protocol features.
Hm, depends on the perspective.
Sure, if one compares success of MIP6 vs e.g. that flash of ND one is
quickly deceived, seeing ND there everywhere whereas MIP6 only recently
getting tract in the mainline open unix distribs.
However, if one compares MIP6 deployment success to that of DHCPv6, one
gets a different picture.
RO is different yet. Discouraging is to know that every single CN would
need it. Encouraging is to see that only recently google and social
nets went IPv6 - on this scale we should wait a few more years to see
first signs of RO deployment.
Alex
You need an HA and associated AAA infrastucture. This is just for
base MIP, without even getting to RO.
To date, I am not aware of any plans to deploy MIPv6. Sure, one can
argue that we have to get IPv6 deployed first, and then folk will
use MIPv6 as well, but I think that is also simplistic thinking. I
believe deploying and using MIPv6 (and the RO functionality
specifically) is still something we lack significant experience
with.
This is one feature of Mobile IPv6 that stands out.
Yes. But only for those who think MIPv6 is something they want to
use.
I think the IPv4 experience with MIPv4 suggests that there are
target scenarios where MIP technology is quite useful, but at the
same time, there is no broad general need for MIP. The vast majority
of the Internet seems to be doing Just Fine without using MIP.
WEll. I wanted to remark to this specific point. I
The semantics of RO, say Type-II RH, is part of the basic IPv6
feature. Most IPv6 stacks have support for these options and in
most cases the RO procedure as well. Given this, It is very
important that the IPv6 Correspondent Node functionality is
mandated on every IPv6 node. However, the Home Agent functionality
on IPv6 routers, or the Mobile Node stack on a IPv6 node, can be
optional, that is fine. But, its important that the end-points has
natural RO support.
I'm strongly opposed to mandating CN support for RO on general
purpose nodes (clients and servers) until:
a) we have significant experience with the technology showing that
it works in practice (i.e, in significant operational deployments),
and
b) there is a more realistic sense that the technology would
actually get used, if it were available.
MIP appears to (possibly) be a "nice to have" feature. But it is not
a critical part of IPv6. It is not the job of the IETF to broadly
mandate functionality that is not clearly necessary.
2.) I'd additionally remove the comments around lack of deployment
experience around the protocol. This comment applies to practically
every IPv6 feature, SEND or other extensions. In fact with Mobile
IPv4 being a core mobility protocol in CDMA, we probably have bit
more related experience on the node requirements from IPv6 node
perspective.
We do not have experience with the RO part of MIP. that is new not
only to IPv6, but to IP overall.
SEND is also (IMO) not something we can recommend. We need more real
deployment/usage experience with it before it is appropriate to
mandate it.
Indeed, per previous discussions on this list, SEND is listed only
as a MAY in the current node requirements ID.
Thomas
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