Le 20/10/2012 23:51, Thierry Ernst a écrit :
Dear Alex,
Would you explain why the vehicle would need to get a new prefix (and
thus I assume configure all the nodes in the vehicle) every time it
enters a new area ?
Well, whenever MR of a vehicle changes its attachment point it would get
a new different address, right? I can only suppose it would get a
different delegated prefix as well. It's hard to imagine that it would
get a different address but a same delegated prefix, no? (it's hard to
make same prefix valid at so many different places, harder than doing it
with addresses and it's not done with them).
Or do you ask why LV gets a new prefix when IV changes its prefix? I
think this is obvious, no? (for topological correctness, right?)
Or do you ask from the NEMO perspective?
In this V2V2I work we first consider there's no MIP nor NEMO neither on
IV nor on LV. We'll see later about adding MIP. We can discuss it as
well, see how MIP would fit in this.
Is this answering in the direction you made the question?
Alex
Thierry
On 20/10/12 20:10, Alexandru Petrescu wrote:
Le 20/10/2012 18:42, Mikael Abrahamsson a écrit :
On Sat, 20 Oct 2012, Alexandru Petrescu wrote:
One point that guided towards choosing ND over DHCP is
topology. DHCP topology can be relatively complex with
Client/Relay/Server, whereas ND is simpler one-on-one.
There is nothing saying DHCPv6-PD can't be done in a single
device (the router itself). That's what I do in my home, cisco
router, local DHCPv6-PD pool, local DHCPv6-PD server, also
installing routes into RIB.
YEs, because at home one typically puts up the interface once a
month and gets typically the same prefix from ADSL operator as 1
year before.
But with vehicles, one connects a vehicle here and gets a prefix,
then moves in that area and gets another prefix. At that point, if
the router obtaining a prefix wants to delegate further to another
vehicle needs to change the delegated prefix.
This dynamic change between the received prefix and the delegated
prefix is not a matter of DHCP. It can be implemented by like
scripting which are independent of DHCP implementation. One has to
touch the conf files be it of DHCP or of ND.
_and_ Relay (or Server). This may be feasible in practice but
I think it would be cleaner to have distinct protocols on a
same machine for receiving a prefix and for sending a prefix.
What is cleaner is to use existing standards where there already
is running code.
Right, there is cleanliness in reuse. Reuse as much as possible.
There is also the question of availability of DHCP software on
smaller platforms which have no SIM card. It may be easier to
do this with ND in smaller settings.
I'd imagine that there already are 2-3 existing FOSS available
implementations that do what you need for DHCPv6-PD client and
server. Instead you want to invent a new standard and create new
code.
In addition to FOSS (what is FOSS?) DHCP one also needs to
dynamically change the delegated prefix when the assigned prefix
changed.
I'm not saying this shouldn't be done, I'm just saying I don't
really see the rationale for it. I used to hate DHCPv6 role in
IPv6, but after a few years of being exposed to it, I've come to
accept that this is the way it is. There is code going back to a
standard Windows Vista that correctly implements DHCPv6-PD
client, and that is what, 5-6 years ago it was released? I've had
PD in my home on Cisco code for 3-5 years already, with no server
infrastructure at all, just single device doing "everything" for
the role needed.
If this was 2002, I'd agree with you that ND PD could be
feasable, but I believe the train has already left the station
and we should focus on keeping IPv6 stable when it comes to how
it works, and get implementations going, not new standards.
WEll yes, I agree that IPv6 should be kept stable and part of that
may be that we try to make sure that a new proposal does not break
existing implementation. This is a matter of further work.
Alex
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