Subject: (ngtrans) PREFIX usage in NAT-PT

From: "Arun Kumar Dheena" <[email-masked]>
Date: Fri, 6 Jul 2001 16:13:37 +0800

Hi,
     I have question regarding the format of the PREFIX used in NAT-PT (rfc 2766).

The NAT-PT states that, the PREFIX::/96 (the prefix appended to the v4 address in IPv6 packets) can be "any routable prefix the network administrator chooses".

The SIIT (rfc 2766), introduces "IPv4 mapped address",  addresses of the form 0::ffff:a.b.c.d , to used in IPv6 packets to refer to an IPv4 node.    
The question is, does the PREFIX has to be an "IPv4 Mapped address" type? If yes, then the PREFIX cannot be "any routable prefix". Am I missing something?

Secondly, Is it necessary to advertise the PREFIX if the PREFIX is an IPv4 Mapped Address type. ?

(The NAT-PT states that the PREFIX "is" advertised in the stub domain by the NAT-PT and that the packets addressed to this PREFIX will be routed to the NAT-PT). 

Thanks in advance
regards.
arun

---

From: George Tsirtsis <[email-masked]>
Date: Sat, 7 Jul 2001 06:04:34 -0400

-----Original Message-----
From: Arun Kumar Dheena [mailto:[email-masked]]
Sent: Friday, July 06, 2001 9:14 AM
To: [email-masked]
Subject: (ngtrans) PREFIX usage in NAT-PT

Hi,
     I have question regarding the format of the PREFIX used in NAT-PT (rfc
2766).
 
The NAT-PT states that, the PREFIX::/96 (the prefix appended to the v4
address in IPv6 packets) can be "any routable prefix the network
administrator chooses".
 
The SIIT (rfc 2766), introduces "IPv4 mapped address",  addresses of the
form 0::ffff:a.b.c.d , to used in IPv6 packets to refer to an IPv4 node.    
The question is, does the PREFIX has to be an "IPv4 Mapped address" type? If
yes, then the PREFIX cannot be "any routable prefix". Am I missing
something?

GT> Both statements in SIIT and NAT-PT drafts are valid...SIIT, apart from
basic translation provides some hints regarding address usage and what I
would call the default case for the NAT-PT PREFIX too...

Secondly, Is it necessary to advertise the PREFIX if the PREFIX is an IPv4
Mapped Address type. ?

(The NAT-PT states that the PREFIX "is" advertised in the stub domain by the
NAT-PT and that the packets addressed to this PREFIX will be routed to the
NAT-PT). 

GT> The PREFIX in NAT-PT can be any valid prefix and should be advertised in
the stub domain. This way packets to be translated can be directed to a
specific NAT-PT box...and indeed you could configure different parts of a
network to use different NAT-PTs by providing different such PREFIXs. No
need to do that if you use the mapped address per SIIT...which is also a
'valid' PREFIX.

I hope this helps
George

---

From: [email-masked]
Date: Fri, 6 Jul 2001 14:06:28 +0300

Hi,
 
Anyway, the prefix -- "any routable prefix the network administrator
chooses" will give much more convenience to administrator while there are
lots of nodes need to be control. On other hand, chosen prefix can give the
ability of load balance, and it is not a heavy work in implement NAT-PT.
 
BR
Howard

-----Original Message-----
From: ext Arun Kumar Dheena [mailto:[email-masked]]
Sent: 2001?7?6? 16:14
To: [email-masked]
Subject: (ngtrans) PREFIX usage in NAT-PT

Hi,

 

Thanks in advance
regards.
arun

---

From: "Arun Kumar Dheena" <[email-masked]>
Date: Tue, 10 Jul 2001 14:09:12 +0800

> network to use different NAT-PTs by providing different such PREFIXs.

But,  Is it possible to have more than one NAT-PT in a stub domain. (as there are
topology limitations)? If we have more than one, then
how will we guarantee the IP packets "destined" to (some part of) the domain
to traverse that particular NAT-PT. ?

If the NAT-PT is unique to a stub domain, then is it necessary to have the
PREFIX as any valid routable prefix?

>No need to do that if you use the mapped address per SIIT...which is also a
> 'valid' PREFIX.
>
> I hope this helps
> George

Thanks

arun

---

From: George Tsirtsis <[email-masked]>
Date: Wed, 11 Jul 2001 03:35:58 -0400

Wow...I never thought of that...thanks!

-----Original Message-----
From: soohong Park [mailto:[email-masked]]
Sent: Wednesday, July 11, 2001 2:59 AM
To: George Tsirtsis; 'Arun Kumar Dheena'; [email-masked]
Subject: Re: (ngtrans) PREFIX usage in NAT-PT

----- Original Message ----- 
From: George Tsirtsis 
To: 'Arun Kumar Dheena' ; [email-masked] 
Sent: Tuesday, July 10, 2001 6:20 PM
Subject: RE: (ngtrans) PREFIX usage in NAT-PT

Arun,
 
You can have multiple NAT-PTs in a domain as long as the NAT-PT does not
change for the same session...As long as the NAT-PTs have different IPv4
addresses and different IPv6 PREFIXs this should not happen...Remember that
the external IPv4 host sends packets to the internal IPv6 host via the
NAT-PT's IPv4 address....this will always take packets to the same NAT-PT
box...Similarly the internal IPv6 host will send packets to en external IPv4
host using the address PREFIX::IPv4...as long as PREFIX does not change for
the same IPv4 destination the same NAT-PT will be used.
 
I have already also said that you may not use a PREFIX if you do not want
to...go for the SIIT "default" one if you want to and you only have a single
NAT-PT....
 
Then again my advice is not to use NAT-PT at all! go for dual stack instead,
it is not that hard even for small devices....the world will become a better
place this way :-)

/* No, dual stack is not complete and unique solution for using of  IPv6. In
the near future, all transition mechanism (e.g. NATPT ,DSTM,Tunneling....and
so on) are going to use for IPv6. Most of all  the best solution depends on
what network configuration is configured and used. 

soohong       */

George 
-----Original Message-----
From: Arun Kumar Dheena [mailto:[email-masked]]
Sent: Tuesday, July 10, 2001 7:09 AM
To: [email-masked]; George Tsirtsis
Subject: Re: (ngtrans) PREFIX usage in NAT-PT

> network to use different NAT-PTs by providing different such PREFIXs.

But,  Is it possible to have more than one NAT-PT in a stub domain. (as
there are
topology limitations)? If we have more than one, then
how will we guarantee the IP packets "destined" to (some part of) the domain
to traverse that particular NAT-PT. ?

Thanks

arun

-----------------------------
soohong Park
OPICOM Co.,Ltd.
Tel:+82-42-860-1062
PCS:+82-16-221-9209
Email: [email-masked]