Subject: [BEHAVE] duration between 2 rtp-keepalive

From: Xavier Marjou <[email-masked]>
Date: Thu, 1 Jul 2010 17:23:54 +0200

Hi,

In the context of the RTP keepalive draft (AVT's WG draft), there is
the need  to specify the duration between two keepalives for each
transport protocol (cf Section 7 of
http://tools.ietf.org/html/draft-ietf-avt-app-rtp-keepalive-08).

Thus my question is what would be the value for: TCP, DCCP, SCTP?

Thank you,
Xavier

---

From: "Dan Wing" <[email-masked]>
Date: Thu, 1 Jul 2010 11:49:30 -0700

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On
> Behalf Of Xavier Marjou
> Sent: Thursday, July 01, 2010 8:24 AM
> To: [email-masked] WG
> Subject: [BEHAVE] duration between 2 rtp-keepalive
> 
> Hi,
> 

For TCP, RFC5382 says:

   REQ-5:  If a NAT cannot determine whether the endpoints of a TCP
      connection are active, it MAY abandon the session if it has been
      idle for some time.  In such cases, the value of the "established
      connection idle-timeout" MUST NOT be less than 2 hours 4 minutes.
      The value of the "transitory connection idle-timeout" MUST NOT be
      less than 4 minutes.
      a) The value of the NAT idle-timeouts MAY be configurable.

https://fit.nokia.com/lars/tmp/2010-hgw-study.pdf shows the results
of a study including TCP timeouts.  However, that is not cross-
referenced with how often those NATs occur in the field (market share).  
About TCP timeouts, it says:

	"TCP-1: Figure 7 shows the measured TCP binding timeouts.
Because the measured timeouts are highly variable,
the plot uses a log scale to make the differences more visible.
Values for NATs which had not timed out by 24 hours
are not shown.
	be1 has the shortest timeout; it consistently times out TCP
bindings after 239 sec - less than 4 min. More than half of
the devices fail to meet the IETF recommended timeout of
124 min [9]. Some of the NATs appear to retain a TCP bindings
for considerably longer - the seven devices on the right
in Figure 7 still had not timed out their bindings after 24 h,
which was the cutoff for this test."

I am not aware of commercially-available NATs that support DCCP
or SCTP.

-d