It's a small step for TLAs but has huge impact on Stub-ISPs

["Hannes R. Boehm" <]

Hello,

i am concerned about the current draft for IPv6 adress assignment.
Specificaly I am worried about the consequences of the aggregateble
global unicast address scheme for smaller ISPs.

I see the following problems for non-TLA "Users" which run a Multihomed
environment:

(Please correct me or point me to the corresponding documents)

1) Multihoming does not reward you with more stability anymore

Since each Interface gets two or more IPv6 addresses, a existing 
TCP connection breaks if the Line on which the packets come in
goes down.

Of course this could be solved with a new version of TCP, but if you look
at the time it took to develop IPv6 this is in the very distant future
(not including the time it takes for deployment)

(I guess it's the same with UDP - once a programm has choosen a destination
 IP address, it uses it for the whole transaction - if the link fails, 
 the transaction stops )

AND: If the DNS still announces the TLA-1::SLA: Addresses when
    the Line to TLA-1 is down, then some connections fail even if
    the Path via TLA-2 is still up and running.

    -> so: there must be a probing of the connection !within! the application

I fear that the loss of topology information with the TLA scheme
will introduce more problems than those which are obvious at first sight.
  

2) Load balancing gets harder

If a station outside your domain opens a connection to the address 
TLA-1::Interface you cant decide which line the incoming traffic should
go.

It should be possible to do a weighted DNS round robin to decide which
prefix is prepended to the SLA:IntID. But with DNS caching this is
only a very unprecise tool.


I did not find any documents addressing these problems.
Are there any ? Or did only those ISPs that do qualify for TLA
assignments write those drafts ;-) ?


with kind regards
 Hannes


-- 
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| Hannes R. Boehm               debis Systemhaus EDVg              | 
| Network Engineer              Hofmuehlgasse 3-5                  |
| hannes.boehm@localhost         1060 Wien                          |
|                               AUSTRIA                            |
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