Subject: [Mip6] comments to boostrapping (split)

From: Ryuji Wakikawa <[email-masked]>
Date: Wed, 30 Nov 2005 19:00:59 +0900

Hello Authors

Thanks for this documentation and sorry for my delay comments. 
Some comments maybe already pointed out.

Editorial
- MIP6 and Mobile IPv6 are mixed in the document.
- Mobile Node, Host, MN are also mixed.
  (This split scenario is applied to MR as well, using mobile host
  should be avoided. Mobile Node is safer)
- Fig3, 4 HA must send BA instead of BU.

Overall 

- The draft mentions localized HA for route optimization and load
  balancing etc.  The provided texts are a bit unclear. what is the
  relationship between home prefix and home agents? When MN gets a
  localized HA, will it associate different home network served by
  each localized HA?

- The section 5.3.2 for autoconfigured home address assignment looks
  weak.  Although the document recommends some operations, but what is
  the statement of DT? There are several limitation compared to IKE
  HoA assignment in terms of pre-configured homeprefix/length, assumed
  64 length. Shouldn't MIP6 use autoconfigured address?

- When HA assigns static HoA to MN (from HA's address pool), can HA
  skip proxy DAD? It looks redundant. 

- When the static address configuration through IKE, is it possible MN
  requests the previous used HoA to HA? (sorry I did not check IKE doc)

- For DNS refreshment, the document proposes a new timer for DNS
  address expiration. Why not HA delete the HoA from DNS when BC for
  the target MN is expired?

- For DNS refreshment, HA has to wait for sending BA till DNS update
  is completed. It depends on how long it takes for DNS update,
  but MN cannot start communication before the BA. I am not sure using
  BU and BA for DNS update is right way. Defining other message is
  possible solution.

- No alignment requirement for DNS update mobility option? 
- What the MN's operation when DNS update is fail?
  (i.e. return code 128-130).

- The document makes clear how to bootstrap when MN does not have any
  information. However, MN needs to do all the steps every time it
  boots up?  what is the trigger for the bootstrapping operation? 
  For example, my PDA often turn off the power (or WLAN goes to the
  dormant mode). When the node is up or WLAN is up, how does MN
  recover the MIP operation? Is this up to implementations?  Is it
  possible to cache bootstrapping information such as Home
  prefix/length, HA, etc?
  
- This document relies on IKEv2. It might be helpful if it gives
  information or pointer for the case of IKEv1.

regards,
ryuji

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From: Vijay Devarapalli <[email-masked]>
Date: Wed, 30 Nov 2005 11:28:40 -0800

Hi Ryuji,

>   localized HA, will it associate different home network served by

if the MN gets a local HA, then its home prefix and home address
will change. it will be from the local HA.

>   64 length. Shouldn't MIP6 use autoconfigured address?

the preferred solution is where the MN does not assume anything
about the home prefix length. in this case, the MN first sends
a MIP6_HOME_PREFIX attribute in the CFG_REQUEST messages, gets
the home prefix through the CFG_REPLY message, auto-configures
a HoA and then sets up IPsec SAs in the subsequent
CREATE_CHILD_SA exchange. maybe this should be made more
explicit.

>   skip proxy DAD? It looks redundant. 

unless you have MNs on the home link trying to configure
addresses from the same prefix as HA's address pool.

>   requests the previous used HoA to HA? (sorry I did not check IKE doc)

yes. it can propose a HoA in the INTERNAL_IP6_ATTRIBUTE
in the CFG_REQUEST message.

>   the target MN is expired?

this timer is more related to a cleanup the HA needs to
perform once in a while.

>   BU and BA for DNS update is right way. Defining other message is

this is only for the first registration. why do you think
DNS update would take a long time?

> - No alignment requirement for DNS update mobility option? 

nope. FQDN is just a string.

>   (i.e. return code 128-130).

the MN does not have a valid DNS entry if the DNS update
fails.

>   possible to cache bootstrapping information such as Home

I think this is deployment specific. its the configuration
on the mobile node and the HA that decides this.

>   information or pointer for the case of IKEv1.

draft-devarapalli-mip6-ikev1-bootstrap-00.txt :)

Vijay