Re: [MMUSIC] Mirja Kühlewind's Discuss on draft-ietf-mmusic-trickle-ice-sip-14: (with DISCUSS and COMMENT)

["Mirja Kuehlewind (IETF)" <[e-mail]>]

Works for me. 

I not sure the wording is super clear though, just to double check:
You say basically "Implementors MUST […] send only one INFO request per estimated round-trip time (RTT).“ And the you say „RECOMMENDED […] to estimate RTT“. However if you have the first MUST, I guess you also must estimate the RTT…? Or is it also recommended to ICE to send only every 3 seconds if RTT is unknown?

Mirja



> Am 13.05.2018 um 18:27 schrieb Thomas Stach <[e-mail]>:
> 
> Mirja,
> 
> sorry for the loong delay in responding.
> 
> Based on your recommendation I'd re-write section 10.9 as follows
> 
> 10.9.  Rate of INFO Requests
> 
>    Given that IP addresses may be gathered rapidly a Trickle ICE Agent
>    with many network interfaces might create a high rate of INFO
>    requests if every newly detected candidate is trickled individually
>    without aggregation. 
> 
>    Implementors MUST aggregate ICE candidates in
>    case that UDP is used as transport protocol and send only one INFO
>    request per estimated round-trip time (RTT). It is RECOMMENDED that 
>    Trickle ICE implementations also implement a way to estimate RTT, 
>    since [RFC8085] advises that application don't send UDP datagrams 
>    more often than one every 3 seconds if the RTT is unknown.
> 
>    If the INFO requests are sent on top of TCP, which is probably the
>    standard way, this is not an issue for the network anymore, but it
>    can remain one for SIP proxies and other intermediaries forwarding
>    the SIP INFO messages.  Also, an endpoint may not be able to tell
>    that it has congestion controlled transport all the way, such that 
>    the recommendations for UDP remain valid also in case of TCP.
> 
> Would that be aceptable?
> 
> Kind Regards
> Thomas
> 
> 
> On 2018-04-13 17:06, Mirja Kuehlewind (IETF) wrote:
>> Hi again!
>> 
>> I actually looked up the recommendation in RFC8085 section 3.1.3 which says:
>> 
>> "A second case of applications cannot maintain an RTT estimate for
>>        a destination, because the destination does not send return
>>        traffic.  Such applications SHOULD NOT send more than one UDP
>>        datagram every 3 seconds and SHOULD use an even less aggressive
>>        rate when possible."
>> 
>> 
>>> Am 08.04.2018 um 20:57 schrieb Thomas Stach <[e-mail]>
>>> :
>>> 
>>> In general, it is RECOMMENDED that a Trickle ICE Agent sends only one INFO request per RTT.
>>> A quarantine period of 100ms would be on the safe side, but lower values might be fine as well
>>> if the typically deployment scenario assumes a shorter RT.“
>>> 
>> So a recommendation of 100ms is probably not appropriate here. Inline with RFC8085 it would be 3 seconds. Thus it probably makes sense to strongly recommend to implement a way to estimate RTT. Please also add a reference to RFC8085.
>> 
>> Sorry for my late input. I should have double checked with RFC8085 earlier. I hope this can still be addressed appropriately.
>> 
>> Mirja
>> 
>> 
>> 
>