Re: [v6ops] new draft: draft-ietf-v6ops-6204bis

["Hemant Singh (shemant)" <[e-mail]>]

Victor,

-----Original Message-----
From: Victor Kuarsingh [mailto:[e-mail]] 
Sent: Tuesday, October 18, 2011 11:10 PM
To: Hemant Singh (shemant)
Cc: [e-mail]; [e-mail]
Subject: Re: [v6ops] new draft: draft-ietf-v6ops-6204bis


>Sorry If I am getting to the game a bit late on this, but I had a
question
>on section 4.4.3 (Transition Technology Coexistence).

No apologies needed and you are not late.


>I kinda agree with some of the points in this section, but from what I
>read here the suggestion is that we may have multiple transition
>technologies running at the same time on the same home gateway.

>Was this the intention of the text?

One reason is sunsetting. You have 6rd and you want to move to native
IPv6.  Thus there is likelihood of two technologies running
concurrently.  Note even when a CE router is rebooted to move to a new
IP technology (and run old one for a short period) the hosts behind the
CE router may not reset to also move to a new IP tech.   That is why the
CE router has to be prepared to run two IP techs concurrently. 


>My question would be, if I have Native IPv6, why turn on 6RD at all?

See above.

>Also, if I have a native IPv4 address, why turn on DS-Lite?  

Correct.  See bullet DLW-4 in the document. You were running DS-Lite and
are moving to native IPv4.  During sunsetting, both techs have to run
concurrently for a short period.  The periods are determined by DHCP
lease timeout of the roughly two hours of IPv6 prefix deprecation from
RFC 4862.

>Whereas I understand that doing it in this method may speed up
connectivity to the
>network (perhaps it's taking long for the IPv6 addressing to work and I
>already have my IPv4 addressing complete with 6RD parameters), but is
>there a lot of value in this?

>Would a decision tree be warranted in this case?  I.e. Ask for both
IPv6
>and IPv4.. And if I get both, native dual stack is king. 

If the device gets both IPv6 and a public IPv4, then the device goes to
dual-stack mode because then neither of DS-Lite nor 6rd is configured
nor provided in DHCPv4 or DHCPv6 messages.  This is possible with the
current text in the Coexistence section.

>The only hole is see here is if the operator provided an IPv4 address,
and
>IPv6 address but no PD came down.  I guess 6RD may be a good idea.

No PD came down is a very conscious decision by the SP to not allocate
any PD.  It's not like an admin in the SP domain fat-fingered a
provisioning system console.  Even if a SP mis-configuration caused no
PD to be sent to the client, did the SP also not send 6rd configuration
data in the DHCPv4 response?  The SP has can provide 6rd configuration
in the DHCPv4 responses.  Alternatively, the text says, 6rd is manually
configured. 

Hemant