Lazy network operators

Fri Apr 16 12:38:59 UTC 2004

On 16-apr-04, at 8:47, Paul Vixie wrote:

>>> preventing DDoS and IP source address forgery each also break what 
>>> the
>>> IAB calls "the end-to-end model".

>> How so?

> I was thinking of RFC 1958:

>    An end-to-end protocol design should not rely on the maintenance of
>    state (i.e. information about the state of the end-to-end
>    communication) inside the network.

> While this is given as an argument in favour of datagrams (vs. 
> circuits)
> as the best transport model, any stateful NAT or firewall violates it,
> any router or loadbalancer flow-quota violates it, and pretty much 
> anything
> that can be done to protect against DDoS violates it.

To quote Steve Deering: there is good state and there is bad state. 
State that is created by looking at the actual communication and then 
recreated when it's lost isn't necessarily evil. (Although I agree that 
when this stuff is taken too far it breaks e2e, for instance a Pix that 
will happily chop off part of a DNS packet when it decides said packet 
is too long.)

>>> (dunno if you heard, but in spite of 128 bits of address space, the
>>> enterprise user community is now asking for IPv6 NAT.)

>> I hadn't, pointer please?

> <http://www.acu.rl.ac.uk/msn2003/Talks/TimChown.pdf> comes to mind.

Ok, you won't hear me say that Tim doesn't know what he's talking 
about... But this can mean all kinds of things, ranging from "everyone 
will use NAT with IPv6" to "there is probably a misguided soul or two 
who will try this".

> but moreso the folks looking at deployment who absolutely don't want 
> another
> IPv4-like lockin, where provider-assigned addresses mean a huge 
> renumbering
> effort in order to change upstreams, and the expectation that globally
> routeable address blocks will not be available, or will not be cost
> effective, for enterprise or small-ISP use.

Yes, this is a problem. I'm not sure NAT is the solution, though. I 
mean, if you're going to use NAT, why switch to IPv6 in the first 
place?

> nowadays ietf is working on
> what they call NAT-PT as a "transition" strategy, with a new set of 
> heads
> stuffed into the same old sand, whereby the designers think that 
> network
> owners are only going to use it until the ipv6 transition is complete.

Unless I'm very much mistaken, this transition mechanism translates 
from IPv6 to IPv4 and vice versa, NOT from IPv6 to IPv6.

> it's still quite astounding to
> me that when we finish deploying ipv6 we'll still have provider 
> assigned
> addresses that customers are afraid to use beyond the edge of their 
> campus,
> and we'll still have the age-old tension between "i could get global 
> routing
> for that address block" and "i could qualify with my RIR to obtain that
> address block (and afford the fees)".

IETF multi6 wg is working on this problem. Hopefully it's possible to 
come up with something that offers both scalability and functionality, 
as current PI and PA paradigms each only offer one.