Re: And Now for Something Completely Different (was Re: IPv6 news)

[Joe Maimon <jmaimon () ttec com>]

Mike Leber wrote:

> On Sun, 16 Oct 2005, Joe Maimon wrote:
>
>
> For example, if your goal was to have TCP-like sessions between
> identifiers survive network events without globally propagating full
> network topology information about your site (the gripe against classic
> IPv4 BGP) you could have multiple locators associated with any single
> identifier sort of like the same way you can have multiple A records for a
> domain name.  

Real world shows that that doesnt work very well. Multiple A records is 
not usuable practicaly speaking for anything other than load balancing, 
today.

> If the location layer session times out then it would try
> the other locators listed (pick a method of selection) and if it suceeded
> would resume the session transparent to the identifier layer. Design the
> timeout and retransmit algorithm and parameters to achieve the convergence
> times of your choice.
DNS is a good example of something that was designed that way, but few 
people rely on common implementations actualy performing it properly.

> You would need a new protocol stack on the hosts at both ends of
> connections.  By common convention classic TCP hosts could be told to use
> one of the locators (a transition hack, or just run the protocols in
> parallel).  No change would be required to the network, and existing TCP
> could continue to be supported (no flag day).

Appears to me thats what shim6 is (cursory reading + nanog discussions)

> Of course support of this new protocol would be limited to the clients and
> servers that chose to implement it, however this is no less than the
> change required for IPv6 which some hoped would solve the multihoming
> problem (possibly defined as scalably supporting network topology change
> without sessions being interrupted).

Long story short, seperating endpoint/locator does nothing to allow 
multiple paths to a single IP6 address/prefix to scale.