RE: PI/metro/geo [Re: The state of IPv6 multihoming development]

["Tony Hain" <alh-ietf@tndh.net>]

Tony Li wrote:
> Tony,
> 
> This is blatantly unfair.  As an "arms merchant", I fully 
> want to sell gear to all interested parties, both ISPs and 
> enterprise alike.  And, as a certain AD is fond of reminding 
> me, the enterprise is a very big market.  Why would I want to 
> torque the enterprise?

I think you read more into that note than was there. It was not an
attack on anyone, I was simply observing that the recent discussion was
focused on core routing issues.

> 
> Instead, I want to help all parties by growing the net in a 
> reasonable and scalable way.  That should be what we're all 
> trying to do here.

I believe it is, I was just asking if we have the appropriate
representation to make a balanced choice when the hard trade-offs start
being made.

> 
> The operation issues that I know of NEVER favor restricting 
> topology. 

Favoring is not the same as enforcing. 

> In fact, restricting topology is the result of 
> geographic aggregation as it forces providers to interconnect 
> within the aggregation boundary. 

I am not trying to promote any particular solution, just make sure the
requirements of the edge are represented.

> Operational issues instead 
> favor a haphazard, need driven, cost optimized topology.  
> Yes, ok it's chaotic, but it's the result of capitalism at its finest.

It is the 'cost optimized' part that makes the difference. Which pockets
are we talking about protecting? I am not saying we should favor any
particular pocket, just asking if we are doing it unintentionally by the
representatives around the table.

> 
> Provider independence isn't necessarily helped only by PI 
> space. There are other ways.  The real point is to avoid the 
> pain and anguish of renumbering. 

That is one reason; simply being in control of your own destiny is
another. 

>  If we were to go down the 
> GSE path, for example, changing providers simply means 
> changing the "routing gorp". The host identifier remains the 
> same.  You reconfigure your border
> router(s) and you're done.  Infinitely less painful than 
> dealing with the boring things like acutally bringing up a 
> new tail circuit.  ;-)

This argument is continually shot at using the multi-prefix model as not
workable because there are too many static tables inside enterprises
that 'need' to carry the real address for access control. I am not
arguing it is valid or correct, just that the viewpoint exists.

> 
> You are also assuming that aggregation and multihoming are somehow 
> at odds.  They are not.  All you have to do is to disconnect 
> the locator and the identifier as GSE does and aggregate only the 
> locators.  Each host in a multihomed domain has a single 
> identifier, but multiple locators.  No deaggregation happens 
> because the locators are bound to the provider and thus we 
> have good topological 'addressing'.  The enterprise doesn't 
> lose because we tweak the transport to base the pseudoheader 
> on the host identifier and then let the locator be free to be 
> replaced by border routers.  Connections flip back and forth 
> between locators easily.

This model was probably possible 4 years ago, but at this point I doubt
tweaking the pseudoheader can even be on the table. Also, 'freely
replaced' usually sets off the alarm bells of the spoof-sensitive
security types. That does not mean we GSE is hopeless, just that we will
probably have to use something like MIPv6 to mask the label swapping. In
the abstract, there is not much difference between GSE and a Care-of
Address. So for routing & packet forwarding, if the CoA had finer
grained pattern replacement happening the end systems would not be aware
of it. The missing link would be letting the host know what the current
publicly visible address is so it could pass that to the CN.

Tony

> 
> How does this not solve the (non-ideological) issues at hand?
> 
> Tony
> 
> |   -----Original Message-----
> |   From: Tony Hain [mailto:alh-ietf@tndh.net]
> |   Sent: Thursday, October 31, 2002 11:07 PM
> |   To: 'Randy Bush'
> |   Cc: Tony Li; multi6@ops.ietf.org
> |   Subject: RE: PI/metro/geo [Re: The state of IPv6 multihoming
> |   development]
> |   
> |   
> |   Randy Bush wrote:
> |   > </ad hat>
> |   > >> We need to decide which is more important: the 
> scalability and 
> |   > >> durability of the routing subsystem or the convenience of 
> |   > >> non-connection based addressing.  When we have 
> |   consensus on this 
> |   > >> point, then all else will follow.
> |   > > The answer to the question depends on which side of the 
> |   > table you are 
> |   > > sitting on.
> |   > 
> |   > there is little doubt in my mind which side i sit on.  
> |   > interesting that tli seems to be on the same side.  but then 
> |   > he always kinda groked the operational issues.
> |   
> |   Operational issues in the ISP space have always favored 
> restricting
> |   topology or the knowledge about unaggregated parts thereof. 
> |   At the same
> |   time, operational issues in the edge enterprise space 
> favor provider
> |   independence for maximum flexibility. We have 
> |   representative voices for
> |   the ISP issues, where are the comparable voices for the enterprise
> |   issues? The ISP focus carried round 1, so the allocation 
> policy only
> |   allows for strict aggregation via provider blocks. The 
> |   enterprise demand
> |   for multi-homing is the fundamental issue this WG is supposed to
> |   address, but the primary voices are those insisting on maximal
> |   aggregation for the ISP routing system. It is hard to 
> |   believe this will
> |   end up with a well balanced result that considers all the 
> |   requirements.
> |   
> |   Speaking of, we have a requirements doc that needs to get 
> |   published.
> |   
> |   Tony
> |   
> |   
>