Subject: Re: [MOBILE-IP] draft-malinen-mobileip-regreg6-00.txt

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Wed, 26 Jul 2000 05:27:15 +1000

Hello Jari and Charlie,

After reading your draft on regional registration for IPv6, I
came up with the following comments.

General comment:

I believe mandating hop by hop encapsulation-decapsulation between
regional routers will have the following effects:

- We end up with a reserved path in the network, hence you lose
the inherent redundancy that we get with IP routing. ie. if one
of the regional aware routers crash, the MN won't receive anything.

- Encapsulation-decapsulation at each node adds extra and unnecessary
delays.

BTW our draft allows the same scenario, but it also allows the MN
to receive directly from the MAP. So there is a choice and it
depends on the MNs preferences / configuration.

Other comments:

- I believe propagating the BU  in the hierarchy breaks the basic
design of MIPv6. Furthermore, it is not clear from the draft
how you can maintain the SA between the MN and each regional router
if the MN doesn't know they exist. As I understood it, the destination
address of the BU is the access router on the same link as the MN.
I assume from ch 7 that you will do some sort of key distribution
protocol. I still can't see how that would work and more importanly
don't see the need for it.
It seems this would add extra complexity / protocols, for no apparent
benefit.
Please elaborate if I missed something here.

- It is unclear to me how the regional BAck is processed. The draft assumes
there is only one sent back. Is it propagated down the hierarchy ?
If so then how would the SA work ?
If not then what happens if one router fails and the others succeed?

- By not processing the routing header in the regional router, you
are breaking the extension header processing rules in RFC 2460.
I also don't see why this is necessary.

- I have some concerns about the way the inbound packets are routed
within the hierarchy. You mention encapsulation in the draft, but
when it is described it doesn't actually say the same thing. It seems
that the destination address is modified in the original packet.
I know that end to end AH will still work, but this is not a normal
IPv6 stack behaviour and I don't see why it is necessary.

- If the MN decides to register its alt-COA with the HA. I believe
any Site-local packets forwarded by the HA to the MNs COA will be
dropped by the regional router (ie. the owner of the COA).
That's one of the reasons we attach a routing header between the HA
and the MAP.

Regards,
Hesham