Subject: RFC2553 and sockaddr_in6.sin6_flowinfo

From: [email-masked] (Bruce A. Mah)
Date: Mon, 01 Nov 1999 10:40:50 -0800

Dumb question:

According to RFC 2553 (sections 3.3 and 3.4), in a sockaddr_in6, the
sin6_flowinfo member is supposed to hold the "IPv6 traffic class & flow
info".  Why is this member defined as a uint32_t, rather than as a
struct that could allow manipulation of the traffic class and flow
without resorting to bitshifting and htonl()/ntohl()?

Just curious...thanks in advance.

Bruce.

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From: Jim Bound <[email-masked]>
Date: Tue, 02 Nov 1999 10:34:07 -0500

>Dumb question:

Good question.

>without resorting to bitshifting and htonl()/ntohl()?

We left the field as uint32_t becasuse we were not given a green light
on the flowlabel if it is done being broken down or if additional bits
may be needed to support other functions or subfunctions within the
flowlabel set of bits, or if a certain number of bits in the flowlabel
even if not subdivided may cause indirection from the bit pattern.
Hence, felt it wise to just define it as 32bit field. Another reason is
that we are pretty sure of the alignment of uint field not causing
problems for the sockaddr_in6 structure for those wanting to use the
portability section of the spec.

The field can always be loaded into a typedef for processing too.

/jim

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