Subject: [Mip6] Comments on draft-ietf-mip6-nemo-v4traversal-05.txt (DSMIP6)

From: "Samita Chakrabarti" <[email-masked]>
Date: Tue, 11 Sep 2007 15:13:58 -0700

Hello Hesham:

I have been asked to provide review comments on this draft. I am about
a week late for the comments; sorry about that. Please note, some of
my comments may overlap with others' comments.

Overall: The document seems useful as it handles mobility for IPv4 and
IPv6 addressed nodes and traffic. It tries to avoid running multiple
mobility management protocols. But it is not clear from reading the
document how differently it takes care of NEMO situation than regular
MIP6 Home agent equipped with IPv4 packets handling capability.

1) Please provide a separate section on Applicability of this protocol.

2) Currenly MIP4 mobile clients and agents are in deployment; does
DSMIP6 suggest that those clients will have to change to be DSMIP6
compliant? How does running DSMIP6 be more efficient than just running
MIP6 client in addition to MIP4 client -- given that infrastructure
already exists for MIP4 in many deployments.

3) Please clarify in a separate paragraph or section whether DSMIP6
intends to replace MIP4 or it only facilitates IPv4 data traffic
transfer while MIP6 is in operation. Note if it intends to replace
MIP4 as well, then it might add another issue of transitioning of
regular MIP4 clients to DS-version one :-)

4) Is this draft standard track or experimental track (or
informational)? If it is standard track then I think this draft needs
more editorial changes for clarity and interoperability.

Some details:

pg 2:  s/to their home addresses, to their IPv4/IPv6
care-of-addresses/to their home addresses, as well as IPv4/IPv6
care-of-addresses/

The second paragraph in introduction:
The paragraph is unclear. First sentence says "mobile nodes would only
need Mobile IPv6 and [NEMO] to manage mobility while moving within the
Internet; hence eliminating the need to run two mobility management
protocols simultaneously."  The second sentence says "this
specification provides the extensions needed in order to allow Mobile
IPv6 only to be used by dual stack mobile nodes" .
s/sack/stack/

It is not clear which two mobility management protocol it is referring
to ? MIP6 and NEMO ? or MIP6 or MIP4?

Section 2.2 : Please clarify that a dual stack node is using IP6 ESP
transport mode over IP-in-IP (v4) tunnel for prefix soliciation and
advertisments when the mobile is in the IPv4 only network and still
runs MIP6. If this information appears in the beginning of the
paragraph, the readability gets better.

Section 2.3.1:
In which scenarios a mobileIPv6 capabile node would want to keep
corresponding with IPv4 traffic in the IPv6 foreign network? Does this
scenario cover starting a new IPv4 connection in addition to on-going
MIp6 connection? Does it support simultaneous mobility support of IPv4
and IPv6 packets as well ?
Note it adds complexity; it might be useful to state that the IPv4
tunnel, IPv4 home-address, Ipv4 care-of-address are optional features.

For each section of  2.3.1, 2.3.2, 2.3.2.1, 2.3.2.2 , please provide
the inner and outer IP source and destination addresses or provide a
pointer to the relevant example at the appendix.

Section 3.1.1 (IPv4 home address option)

Pref  field  description: What if it is set to zero ? Error condition ?

Section 3.2.1 -- Diagram is divided between two pages.

Section 3.2.2 :
Is it a MUST condition for HA if   a NAT is in path ? It should say
someting about that. If  HA is not behind a NAT, then it should not
send this option (clarify in the doc)

Section 4.1 :  Describe why the TLV formatting is necessary for GRE or
IPSec? Why do we need TLV formatting here ?
--------------------------------------------------------

Thanks,
-Samita

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