Subject: API question

From: Vlad Yasevich <[email-masked]>
Date: Fri, 24 Jun 2005 15:29:37 -0400

Would it make sense to allow a per association TOS setting in SCTP
instead of a per endpoint setting available with IP_TOS option?

I could see this being potentially useful only with 1-to-Many style
sockets.  Since you can have association to multiple destinations, it's
would be possible to designate each association with a different TOS.

What does everyone else think?

-vlad

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From: Michael Tuexen <[email-masked]>
Date: Fri, 24 Jun 2005 22:22:16 +0200

Makes sense to me.

Best regards
Michael

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From: "Peter Lei (peterlei)" <[email-masked]>
Date: Fri, 24 Jun 2005 16:10:43 -0500

Sounds like a good idea, but how do you propose to get the value
of the IP_TOS option?

Recall that not all implementations are able to pass in a assoc_id
value in the getsockopt() call.  Currently, sctp_opt_info() assumes
an IPPROTO_SCTP level.

regards,
--peter

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From: Vlad Yasevich <[email-masked]>
Date: Fri, 24 Jun 2005 23:07:53 -0400

>From an implementation perspective, I was thinking that that would be
an IPPROTO_SCTP level option, something like SCTP_TOS.  The value would
have to be stored per association.

Each association on a 1-to-Many socket can inherit the value of the
IP_TOS, which can then be retrieved by sctp_opt_info.  Additionally
applications can set a per-association TOS to update the default
inherited value.  At this point, new value would be in effect for the
association.

As far as interactions with IP_TOS, new settings of IP_TOS would be
inherited by all associations that did not have SCTP_TOS set.

..

Now that I think about it a bit more, may be we can make it more general
and have it support IPv4 TOS and IPv6 Flowlabel?  I'll have to think
some more on that one...

-vlad