Re: [hybi] updated Charter proposal (NATs and Firewalls)

[Salvatore Loreto <[e-mail]>]

Hi Jamie

see my answers in line


Jamie Lokier wrote:
> Salvatore Loreto wrote:
>   
>> Jamie Lokier wrote:
>>     
>>> Peter Saint-Andre wrote:
>>>  
>>>       
>>>> Somewhere in the text we need to make it clear what kind of intermediate
>>>> entities we're talking about -- does that include entities which are in
>>>> some sense HTTP-aware or HTTP-optimized (proxies, load balancers,
>>>> caches, etc.) or also entities that are in some sense more generalized
>>>> (firewalls, network address translators, etc.).
>>>>    
>>>>         
>>> Firewalls and NATs are quite important to HyBi.  Because the server
>>> can't initiate connections, it's necessary for connections to be kept
>>> open as long as the client wishes to receive messages.  Firewalls and
>>> NATs need enough keepalive packets to stop them blocking a connection
>>> in mid use.  And "ping" requests with responses from one side are
>>> not the most efficient way to do that.
>>>
>>> HyBi may also need a strategy to cope when a firewall or NAT
>>> spontaneously blocks a connection in the middle of it's use too.  That
>>> might be deferred to the application (bet lots of them will get it
>>> wrong if so), but it should at least be addressed.
>>>  
>>>       
>> I agree that we have to take in consideration Firewalls and NATs during 
>> the design of a Bidirectional protocol
>> (both short and long term), and this is extremely important for HyBi.
>> However the HyBi wg should not have any ambition to improve the 
>> Firewalls and NATs, but only design a protocol that
>> cooperate well with them and improve the existing HTTP entities to 
>> improve the interaction with the existing Firewalls and NATs.
>>     
>
> Fwiw, I agree completely.
>
> It may involve characterising firewalls and NATs, for example to
> suggest keepalive message rates and strategies.  I wouldn't be
> surprised if another part of IETF has investigated that already in a
> more general context or for some other protocol.
>   
[Sal] IETF behave wg is working on this aspects: 
http://tools.ietf.org/wg/behave/
have a look at "NAT Behavior Discovery Using STUN" draft: 
http://tools.ietf.org/html/draft-ietf-behave-nat-behavior-discovery-08

> The issue of connections being dropped, and detecting when this has
> happened, and perhaps recovering, is more general than firewalls and
> NATs.  E.g. mobile IP has the same problem.  I don't know if it needs
> to appear anywhere in HyBi or if it can be dealt with entirely in the
> application layer.  But it is worth looking at, because a web full of
> applications which deal with it badly is a less desirable outcome than
> a web full of applications which handle it well, and we _might_ be
> able to make a big difference there.
>   
[Sal] of course the issue of detecting a connection being dropped is a 
more general problem that can happen
in several scenario other then in firewalls/nats.
Do you have a text/statement proposal to insert in the chart about it?
> -- Jamie
>