Subject: [MEXT] NEMO-PD - DHCP support on Mobile Network

From: "Teco Boot" <[email-masked]>
Date: Thu, 6 Dec 2007 19:58:13 +0100

On the two drafts for NEMO prefix delegation, I wonder how we can support
DHCP on Mobile Network. I think there are two options, DHCP Relay or running
DHCP Server on MR itself. For the latter, we need not only a prefix, but
also data for DHCP options.

Remark on overhead, I think the prefix delegation signaling has low
overhead, depending on lifetimes. Lifetime can be a order longer that BU
(PD: hours, days, months; BU: seconds, minutes).

Teco.

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From: Alexandru Petrescu <[email-masked]>
Date: Thu, 06 Dec 2007 13:23:27 -0800

Teco Boot wrote:
> On the two drafts for NEMO prefix delegation, I wonder how we can 
> support DHCP on Mobile Network. I think there are two options, DHCP 
> Relay or running DHCP Server on MR itself. For the latter, we need
> not only a prefix, but also data for DHCP options.

I think one additional possibility suggested by Francis was to use a
DHCPv6 Relay co-located with a DHCPv6 Client - in the Mobile Router(!)

In my understanding, this would relieve from the potential problem of
putting the DHCPv6 Solicit multicast message in the MR-HA tunnel
(virtual interface) - because the DHCPv6 Relay (MR) would know the
unicast address of the DHCPv6 Server, no need to tunnel.  I'm not sure
though whether in IPv6 the Relay uses a unicast address to forward the
Solicit, or a multicast.

There are of course other possibilities for DHCPv6 with NEMO and I
currently think like many have their advantages.

Software availability should be taken into account too.

> overhead, depending on lifetimes. Lifetime can be a order longer that
> BU (PD: hours, days, months; BU: seconds, minutes).

I think a binding could last more than a few minutes.

I think we can try to compare number of signalling messages of using
DHCPv6-PD for delegating the MNP vs the MIPv6-BU-PD extensions.  I think
the signalling is probably on the same scale.

Alex

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From: "Templin, Fred L" <[email-masked]>
Date: Thu, 6 Dec 2007 13:26:36 -0800

> -----Original Message-----
> From: Alexandru Petrescu [mailto:[email-masked]] 
> Sent: Thursday, December 06, 2007 1:23 PM
> To: Teco Boot
> Cc: [email-masked]
> Subject: Re: [MEXT] NEMO-PD - DHCP support on Mobile Network
> 
> Teco Boot wrote:

This has been documented in 'draft-templin-autoconf-dhcp'
for some time.

Fred
[email-masked]

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From: Alexandru Petrescu <[email-masked]>
Date: Thu, 06 Dec 2007 14:13:32 -0800

> This has been documented in 'draft-templin-autoconf-dhcp'

Fred,

I agree.  It says so at top of page 10.  Looks as me having missed this 
earlier reference.

 From an implementation standpoint there are however some issues with 
this.  If the Relay uses a multicast address to talk to the Server then 
we'd still have some potential issues putting multicast packets 
(Solicit) in the MR-HA tunnel.  The other issue may be related to 
whether implementations of DHCPv6-PD support Relay or not and how.

Alex

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From: Francis Dupont <[email-masked]>
Date: Fri, 07 Dec 2007 01:01:19 +0100

In your previous mail you wrote:

   I'm not sure though whether in IPv6 the Relay uses a unicast
   address to forward the Solicit, or a multicast.
   
=> it uses what you have configured to use so if you give server address(es)
it uses it (them), if you leave it to guess it uses the multicast service
address...

[email-masked]

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From: Francis Dupont <[email-masked]>
Date: Fri, 07 Dec 2007 01:12:55 +0100

From an implementation standpoint there are however some issues with 
   this.  If the Relay uses a multicast address to talk to the Server then 
   we'd still have some potential issues putting multicast packets 
   (Solicit) in the MR-HA tunnel.

=> it is so easy to configure the relay with the address of the agent at
the HA side of the tunnel you should not expect it is not done.

   The other issue may be related to whether implementations of
   DHCPv6-PD support Relay or not and how.
   
=> IMHO a DHCPv6-PD implementation without Relay support is useless, not
as an implementation without Client or Server but near.

Thanks

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From: Alexandru Petrescu <[email-masked]>
Date: Thu, 06 Dec 2007 16:45:14 -0800

> the HA side of the tunnel you should not expect it is not done.

If so, then the issue is then how to quickly configure the HA address on 
the MR, prior to MR sending this Solicit.

> as an implementation without Client or Server but near.

One DHCPv6 implementation will simply crash the Relay when requesting a 
IPv6 prefix through it.  (state of affairs a few weeks ago).

Alex