Subject: [netlmm] Comments on I-D: draft-ietf-netlmm-pmip6-ipv4-support-05.txt

From: Basavaraj Patil <[email-masked]>
Date: Thu, 23 Oct 2008 01:05:23 -0500

Hello,
 
Comments on I-D: draft-ietf-netlmm-pmip6-ipv4-support-05.txt

Set: 1

1. s/1) extending IPv4 home address mobility support to the
   mobile node/Enable IPv4 address assignment with mobility support
   for an MN. 

2. The I-D uses the term IPv4 home address for the address assigned by
   the LMA to an MN. Since there is really no IPv4 CoA for the MN, I
   think it is better to simply refer to it as the MNs IPv4
   address. 

3. I-D states: 
   "The mobile node is not required to be
      allocated or assigned an IPv6 address for enabling IPv4 home
      address support."

   Why not assign the MN an IPv6 prefix all the time? Even if the MN
   does not request the IPv6 prefix, it would be useful in some
   scenarios to have the BCE include the assigned prefix all the
   time. An example scenario is one where the MN (DS) attaches to the
   network but would be assigned an IPv4 address only when it is
   needed. In such a case the MAG/LMA create state for the MN and do
   not have to establish the binding only when the IPv4 address is
   requested. The MN does not really use the IPv6 prefix. But if the
   LMA does not assign an IPv6 preifx there would be no BCE for the MN
   if only a v4 address is requested. Is there a concern that
   assigning a v6 prefix in all instances would be considered a waste
   of resources? It is better to assign an MN a v6 prefix all the time
   and not worry about whether the MN is DS capable.

4. I-D states:
   "furthermore the
      mobile access gateway may be using an IPv4 private address and
      with NAT [RFC-3022] translation devices on the path to the local
      mobility anchor."

     Having a private IPv4 address assigned to the MAG and dealing
     with NATs on the path will make this solution complex. Is there
     really a need to have RFC1918 addresses assigned to the MAG?
     
5. s/mobile node can be operating in IPv4-only, IPv6-only or in
      dual mode/MN can be an IPv4 only or a dual-stack host

6. Statement:
   "For enabling IPv4 home address mobility support to a mobile node,
      it is not required that the IPv6 home address mobility support
      needs to enabled.  However, the respective protocol(s) support
      must be enabled on the access link between the mobile node and
      the MAG"

   What specifically are you expecting to be enabled on the access
   link between the MN and MAG? An example would be useful.

7. I-D states:
   "The mobile node can obtain an IPv4 address for its attached
      interface.  Based on the type of link, it may be able to acquire
      its IPv4 address configuration using DHCP [RFC-2131], IPCP [RFC-
      1332], IKEv2 [RFC-4306], static configuration or through other
      standard IPv4 address configuration mechanisms."

      What other standard IPv4 address config mechanisms are you
      refering to here? Are you refering to address assignment during
      PDP context establishment in GPRS networks?

8. s/more than one mobile node sharing different addresses
      from the same IPv4 subnet./multiple mobile nodes that are
      assigned IPv4 addresses from the same subnet.

9. Sec 2.2 IPv4-Proxy-CoA
   The I-D says that the IPv4 PCoA address in the case of a NAT being
   on the path is the address allocated by the NAT. But this address
   could change, right?

10. s/Further, if the mobile node connects to
      the Proxy Mobile IPv6 domain through multiple interfaces and for
      simultaneous access, each of the attached interface will be
      assigned a unique IPv4 home address./If the MN connects to the
      PMIP6 domain via multiple interfaces each of the interfaces are
      assigned a unique IPv4 address.

11. Encapsulation of IPv6 over IPv4 is not mentioned in the list of
    Encapsulation modes?

12. s/When an IPv4-enabled or a dual-stack enabled mobile node
    attaches to/When an IPv4 or DS MN attaches to

13. s/Upon the completion of the
   signaling, the local mobility anchor and the mobile access gateway
   will have the required routing states for allowing the mobile node to
   use its IPv4 home address from its current point of attachment./On
   successfull completion of PMIP6 signaling, the LMA and MAG
   establish routing states for the MN w.r.t the assigned IPv4
   address. 

14. It would be good to explain how you see IKEv2 being used between
    the MN and MAG for IPv4 address assignment. Generally the MN does
    not do IKEv2 signaling with its default router (MAG). But since
    you are covering the scenario where the VPN-GW acts as the DR/MAG,
    it needs to be clarified.

15. I-D states: 
    "A mobile node will be able to obtain
   IPv4-only, IPv6-only or dual IPv4/IPv6 address configuration for its
   attached interface."

   Maybe it would be worthwhile considering the BCE to be IPv6 only or
   IPv6/IPv4. An IPv4 only BCE may be dropped (?).

16. I-D states:
    "The mobile node's policy profile will determine
   if the mobile node is entitled for both the protocol versions or a
   single protocol version. "

   What exactly is the reason for having such authorization by the
   policy profile? The policy profile may not be aware of the MNs
   capability in terms of whether it is a dual-stack host or an IPv4
   only host. If mobility support is authorized for an MN, why control
   whether it is restricted to IPv6 or IPv4 only vs whatever the host
   is capable of.

17. s/Additionally, If the mobile node connects to the Proxy Mobile IPv6
   domain, through multiple interfaces and simultaneously through
   different access networks, each of the connected interfaces will
   obtain an IPv4 home address from different subnets.  In such
   scenario, there will be multiple Binding Cache entries for the mobile
   node on the local mobility anchor.  All the address (IPv4/IPv6)
   assigned to a given interface will be managed as part of one mobility
   session, as specified in Section 5.4 of [RFC-5213]./If the MN
   connects via multiple interfaces simultaneously, each interface is
   assigned a unique IPv4 address. The LMA creates multiple BCEs for
   the MN in such a scenario. Each BCE is viewed as being a separate
   mobility session as per Sec 5.4 of [RFC-5213].

Will send the rest shortly.

-Raj

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