RFC 6926

[Matthias Scheler]

Hello,

it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.

RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

Kind regards

[Greg Troxel]

Post by Matthias Scheler
Hello,
it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.
RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?



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[Greg Troxel]

Post by Greg Troxel

Post by Matthias Scheler
Hello,
it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.
RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?

Also, what do other BSDs and Solaris do?


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[Matthias Scheler]

Post by Greg Troxel

Post by Greg Troxel

Post by Matthias Scheler
it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.
RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?

Also, what do other BSDs and Solaris do?

I don't know. But Linux uses 10 in kernel 3.2 and newer. And Google
and a lot of other web companies heavily advertise this feature e.g.
during the Velocity 2013 in Londing.

Kind regards

[Loganaden Velvindron]

Post by Matthias Scheler

Post by Greg Troxel

Post by Greg Troxel

Post by Matthias Scheler
it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.
RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?

Also, what do other BSDs and Solaris do?

I don't know. But Linux uses 10 in kernel 3.2 and newer. And Google
and a lot of other web companies heavily advertise this feature e.g.
during the Velocity 2013 in Londing.

I sent a patch some time ago ;-)

Post by Matthias Scheler
Kind regards
--
Matthias Scheler http://zhadum.org.uk/

[Loganaden Velvindron]

Post by Matthias Scheler

Post by Greg Troxel

Post by Greg Troxel

Post by Matthias Scheler
it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.
RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?

Also, what do other BSDs and Solaris do?

I don't know. But Linux uses 10 in kernel 3.2 and newer. And Google
and a lot of other web companies heavily advertise this feature e.g.
during the Velocity 2013 in Londing.

http://mail-index.netbsd.org/tech-net/2013/03/29/msg003962.html

Post by Matthias Scheler
Kind regards
--
Matthias Scheler http://zhadum.org.uk/

[Christos Zoulas]

Post by Matthias Scheler

Post by Greg Troxel

Post by Greg Troxel

Post by Matthias Scheler
it seems that NetBSD's TCP implementation still follows RFC 3390
and uses 4 as the initial TCP congestion window size.
RFC 6928 increased the the initial size to 10. Is there any reason
not to change NetBSD's default accordingly?

That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?

Also, what do other BSDs and Solaris do?

I don't know. But Linux uses 10 in kernel 3.2 and newer. And Google
and a lot of other web companies heavily advertise this feature e.g.
during the Velocity 2013 in Londing.

You can compile a custom kernel:

tcp_subr.c:#ifndef TCP_INIT_WIN
tcp_subr.c:#define TCP_INIT_WIN 4 /* initial slow start window */
tcp_subr.c:#ifndef TCP_INIT_WIN_LOCAL
tcp_subr.c:#define TCP_INIT_WIN_LOCAL 4 /* initial slow start window for local nets */

Or use sysctl to tune it dynamically:

$ sysctl -a | grep init_win
net.inet.tcp.init_win = 4
net.inet.tcp.init_win_local = 4
net.inet6.tcp6.init_win = 4
net.inet6.tcp6.init_win_local = 4

We ship by default with 4 because this is what the current recommendation is
(still). The local variations affect only connections with destinations on
the local subnet.

christos


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[Ted Lemon]

Post by Greg Troxel
That's EXPERIMENTAL, not PROPOSED STANDARD. What do the standards
track congestion control documents say about actually doing it (vs an
experimental RFC)?

It might be worth asking these questions on the relevant IETF mailing lists rather than here. There's a tremendous amount of interest in this in the IETF right now, so you will probably get some good answers. It might also be worth looking at what they're doing in terms of active queue management.


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