On 9/09/10 4:28 PM, "Alexandru Petrescu"
Le 09/09/2010 08:01, Hesham Soliman a écrit :
On 9/09/10 3:54 PM, "Wassim
On Sep 8, 2010, at 7:58 AM, Alexandru Petrescu wrote:
I agree mainly with the document draft-ietf-mext-nemo-pd.
It is good and needed to dynamically assign a Mobile Network
Prefix to the NEMO-enabled Mobile Router.
However, here are a couple of missing points.
One missing point is about how will the Mobile Router configure
its default route on the home link? I thought Prefix Delegation
would bring DHCP in the picture and would allow MR to synthesize
a default route even though RAs are absent. But I now realize
that a DHCPv6-PD implementation (and std?) does not allow a
router (MR) to synthesize its default route (neither RA does, nor
=> I think the MR can easily act as a host on its egress interface
and configure its default/next hop router that way. Of course the
other alternative is to use routing protocols, but I think using ND
should be sufficient.
Hesham - when at home, the MR acts as a router (ip_forward==1,
join all-routers group), as such ND is insufficient to obtain the
default route - it's a Router.
When at home, and using DHCPv-PD, the MR also acquires its Home Address
with DHCPv6. If so, then it doesn't use SLAAC to auto-configure neither
a Home Address nor a default route.
In implementation it is of course possible to dynamically change MR
behaviour from Host to Router: be at home, first act as host (fwd==0) to
acquire the Home Address and default route, then set fwd=1 and use
DHCPv6-PD to acquire a prefix (but not the Home Address) and take
advantage of the default route acquired previously as a Host. This is
one way of solving the issue.
However it is not specified.
=> Who cares, specify it in your product description. The IETF doesn't
specify how to build products. If you want to solve this with protocols then
use routing protocols. Of course you need to solve the security issues when
the MR moves.
I am not
sure how clean is it anyways to disregard that 'M' bit of RA anyways.
The alternative to using routing protocols (OSPF?) to communicate a
default route to the MR - I am not sure how this could work, never seen
it in practice.
=> For a good reason! You need to work out trust across domains.
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