Subject: Re: IPv6 for mobile telephony

From: Hossam Afifi <[email-masked]>
Date: Mon, 28 Jun 1999 11:51:57 +0200

Thank you for your comments

 The drafts was written in a hurry to meet with the ietf submission deadline.

 What we propose for addressing  is the use of a 32 bit long prefix identifying
the MSC and
 the rest holding the user MS-ISDN number to keep track of his mobility through
different MSCs.

 In what concerns the security, we would like to be able de disable any packets
from outside the GSM
 network if the user wishes so. So we suggest a label that would be put in
every packet to filter the
 packets that are not welcomed and to protect your air resources.

 For the differences with GPRS we say that you should not have a separate
entity called GGSN because
 it will add complexity to the system and it will need updates between MSC and
GGSN. We would like
 to modify the CC and MM messages to include all that without the need of
encapsulation protocols as
 described in GPRS.

Hossam

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From: Thomas Eklund <[email-masked]>
Date: Mon, 28 Jun 1999 11:42:00 +0200

There is a lot of confusion in this draft.
To me it seams that you try to specify whats already in place in GPRS....
What is the benefit of yor proposal? I dont see it!

First of all in sec 2.2. you say that an IPv6 address is current MSC prefix
+ e.164 number that means that a MSC prefic could only be 8 bits long
(128-120) and that would take up a big space of the TLA domain...

I would suggest that you set one of the prefix bits in IPv6 to be assigned
for the e.164 addressing...:

011 + 5 bits unassigned + 120 bits e.164 addressing. And I think that the AD
should consider this! Because that means that the hole telecom world would
not need to renumber. 

Another thing in 3:
In GPRS today there is already specified how you connect a DHCP server for
address management in GGSN

Chapter4:
You will NEVER use IPsec over GSM or GPRS due to the overhead! You already
have ciphering today over the air and that does not introduce any
overhead... This is handeled at layer 2 in GSM/GPRS....

Chapter 5:
Does that mean that you suggest to always use  dynamic DNS in mobile IP
network? 

Best Regards 
 Thomas Eklund, SwitchCore

> -----Original Message-----
> From: Hossam Afifi [mailto:[email-masked]]
> Sent: Thursday, June 24, 1999 7:53 PM
> To: [email-masked]
> Subject: IPv6 for mobile telephony
> 
> 
> 
>  A draft has been sent to the internet draft secretary on 
> IPv6 in Mobile
> Telephony
>  the document is also available from
> http://www.rennes.enst-bretagne.fr/~afifi/e164ipv6.asc
> 
>  your comments are welcomed.
> 
> Hossam
>

---

From: Bill Sommerfeld <[email-masked]>
Date: Mon, 28 Jun 1999 10:21:00 -0400

> overhead... This is handeled at layer 2 in GSM/GPRS....

link-layer encryption is not end-to-end encryption; most importantly,
the trust properties are completely different.

Also NEVER is a very strong word.  Certainly, I can see that some
applications would be willing to pay the additional overhead when they
need end-to-end encryption (rather than sending in the clear over the
internet to the GSM base station and then trusting the GSM base
station to encrypt for them).

					- Bill

---

From: "Perry E. Metzger" <[email-masked]>
Date: 28 Jun 1999 11:49:53 -0400

> overhead... This is handeled at layer 2 in GSM/GPRS....

I must respectfully disagree with this statement.

0) GSM's link encryption is, to put it bluntly, garbage.
1) Link layer encryption is not a substitute for end to end
   encryption. Just protecting a single hop is not going 
   to cut it.
2) The overhead of IPSec is very modest in practice.

Perry

---

From: Lloyd Wood <[email-masked]>
Date: Mon, 28 Jun 1999 14:13:54 +0100 (BST)

> overhead... This is handeled at layer 2 in GSM/GPRS....

Er, what overhead?

The only real security is end-to-end security. Air-interface-only
encryption provided by someone else isn't security. How can you claim
that ciphering over the air not introduce any overhead, when you claim
that IPsec does?

IPSec _will_ be increasingly used over GSM and GPRS. Any drafts in
this area should address this.

L.

If you want secure voice communications over GSM, you might buy two of
these mobile handsets: http://www.crypto.ch/product/hc2000_e.html#end

> >  your comments are welcomed.

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>

---

From: Ignatios Souvatzis <[email-masked]>
Date: Tue, 29 Jun 1999 12:49:39 +0200

> 0) GSM's link encryption is, to put it bluntly, garbage.

... and only used (in practice) from your phone to the base station, but not
in between base stations. This is a feature demanded by the ... uhm... 
security agencies. At least in Europe.

That is: if you are near the line of sight between two base stations, you
can copy the traffic in clear{voice,text}.

	-is

---

From: Lloyd Wood <[email-masked]>
Date: Tue, 29 Jun 1999 12:06:04 +0100 (BST)

> can copy the traffic in clear{voice,text}.

http://catless.ncl.ac.uk/Risks/19.48.html#subj5.1

discusses this in some detail. I don't have a reference for the paper
promised at end.

L.

mobile air interface != other dumb things in the mobile provider network.