[e2e] overlay over TCP

[Dan Wing]

On Jan 21, 2005, at 12:15 PM, David P. Reed wrote:

> Dan Wing wrote:
>
>>
>> Yes, combined with little market demand, as yet, for a NAT to handle 
>> SCTP.
>
> There is this chicken/egg problem.  If SCTP doesn't work over NATs it 
> won't be used for applications where NATs are heavily used.   Then 
> there won't be demand (at least no evidence of it).

This egg was demonstrably cooked with IPsec, which had the same 
problem.  IPsec "passthru" was implemented on nearly all vendor's 
residential NATs at about the same time IPsec-over-UDP was beginning to 
hit the market.  Passthru works by examining SPI's and simple 
mechanisms have drawbacks (only one session through the NAT, or only 
one session to a specific remote IP address, for example), and 
IPsec-over-UDP has even more packet bloat than IPsec itself.

I expect DCCP, SCTP, and other new protocols will suffer the same 
awkward deployment unless we (in the collective sense) improve the 
situation with guidance from people familiar with those new protocols.  
draft-xie-tsvwg-sctp-nat-00.txt is a move in the right direction, 
although it seems NATting SCTP may well be complex.

> There's a difference between "demand" (meaning actual use) and 
> "demand" meaning I would ask and pay to use it if I thought I had any 
> chance of getting it from the blind turkeys who sell things like NAT 
> boxes.
>
> Reminds me of 1992 when a Nynex VP told me there was *no demand* for 
> data connectivity between people working at home and their offices.  I 
> pointed out that companies like DEC and MIT employed 10's of thousands 
> of people who were using terminals to connect to computers at work.   
> His response was that they had carefully analyzed measured data use 
> and I was wrong.   I asked how they measured modems over home phone 
> lines, thinking they could listen for modem tones or something, and he 
> said (I'm not joking): "I thought that was illegal!"  It turns out 
> that what they called "data" was a dedicated "data circuit" and that 
> modems were "voice".

:-)

-d