Subject: [MMUSIC] Transport expertise needed at the ICE WG

From: Ari Keränen <[email-masked]>
Date: Tue, 20 Oct 2015 13:38:49 +0300

Hi all,

The new ICE working group was recently chartered and one reason for 
splitting this WG from MMUSIC WG was to get more folks with transport 
expertise involved.

One long-standing issue with the new revision of the ICE specification 
[1] has been finding a proper value for the transaction pacing parameter 
which governs, e.g., how fast connectivity check packets can be sent. In 
the original ICE RFC this value was set for RTP traffic minimum 20 ms 
and for non-RTP traffic minimum 500 ms [2].

The lower the pacing value, potentially faster the ICE process 
concludes, which is obviously very desirable. However, setting a too low 
value may result in overloading the NATs (they can create new binding 
only so fast) and also congesting the links so that connectivity check 
packets are lost and result in false negatives.

However, because such conservative value (500 ms) was selected for 
non-RTP traffic, in practice most implementations ignore this 
recommendation. Also the validity of the RTP traffic's 20 ms minimum 
interval has been questioned for modern networks. Now when we are 
revising the ICE specification, we'd like to select better values for these.

Therefore, we would also like to hear from transport area experts what 
would you consider a reasonable lower bound for the transaction pacing 
parameter today.

At the Yokohama meeting we are planning to have a slot at the ICE WG 
session dedicated on this topic and we would welcome your input there. 
And before the meeting please share your views on the ICE working group 
mailing list: https://www.ietf.org/mailman/listinfo/ice

Thanks,
Ari & Peter (ICE WG co-chairs)

[1] https://tools.ietf.org/html/draft-ietf-ice-rfc5245bis-00
[2] https://tools.ietf.org/html/rfc5245#section-16