Subject: [MEXT] DSMIPv6 Dynamic Prefix Allocation/Home Address & Prefix Length

From: Joel Hortelius <[email-masked]>
Date: Thu, 26 Jun 2008 11:15:19 +0000

Hi;

A question regarding the home address/home address ack options;

In the ACK option, if I request a home address(not a prefix), will it be
set to '32' or will it be set to the subnet length of the network the
home address belongs to?

If its set to the network subnet length, which would provide more
information and making "returning home" much easier, I can see no way I
can differ it from a dynamic prefix allocation in the same request; that
is if I request 0.0.0.0/32, and 0.0.0.0/24 with P flag set, there's no
way currently to figure which of the ack options contain the reply,
since both may be returned with /24 prefix length?

Why does not the ack also contain the PREFIX flag, if it's in reply to a
PREFIX allocation?

Regards,
Joel Hortelius.

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From: Hesham Soliman <[email-masked]>
Date: Thu, 26 Jun 2008 22:14:00 +1000

> set to '32' or will it be set to the subnet length of the network the

=> It will be set to 32.

> information and making "returning home" much easier,

=> The spec does not detect "returning home" using IPv4. This spec assumes
the home network MUST be IPv6 enabled, therefore movement detection for the
home network is done according to DNAv6 and RFC3775.

> Why does not the ack also contain the PREFIX flag, if it's in reply to a

=> Because it adds no information for the purpose of the spec.

Hesham

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From: Joel Hortelius <[email-masked]>
Date: Thu, 26 Jun 2008 14:02:35 +0000

Still; If you use a v4 home address, you need to set up routing for that
particular domain as well when returning home; v6 is not an issue,
that's properly resolved, but for v4 you'd either need to resolve the
prefix length somehow (using DHCP, perhaps), or have it statically
configured; otherwise it'd be difficult to resolve what subnet mask to
assign to the "returned home" interface for the v4 address.

As it stands now, the information received through the DSMIPv6 options
allows me to easily set up tunneling regarding the v4 domain; but not as
easily set up a working "home" environment, which I assume should also
be possible; I only have address/32; which is not really assignable on
an interface if you want it usable.

Regards,
/J.

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From: Sri Gundavelli <[email-masked]>
Date: Thu, 26 Jun 2008 09:24:49 -0700 (PDT)

>> set to '32' or will it be set to the subnet length of the network the

Since, the (P) flag is there, to indicate if its a host address or
a prefix, returning the actual prefix length will be useful, instead
of returning 32, and HA has the prefix length.

Sri

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From: "Vijay Devarapalli" <[email-masked]>
Date: Thu, 26 Jun 2008 21:01:07 -0400

One possible simplification is to set the 'P' flag in both the request
and the reply whenever a prefix is requested/returned.

In case a single address is being sent, the "prefix-len" field would be
used to carry the network subnet length. The 'P' flag would be unset.

Comments?

Vijay

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf
> Of Sri Gundavelli
> Sent: Thursday, June 26, 2008 9:25 AM
> To: Hesham Soliman
> Cc: [email-masked]
> Subject: Re: [MEXT] DSMIPv6 Dynamic Prefix Allocation/Home Address &
> Prefix Length
> 
> 
>

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From: Sri Gundavelli <[email-masked]>
Date: Thu, 26 Jun 2008 18:06:42 -0700 (PDT)

That's what I'm suggesting as well.

Sri