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IPv6 and QoS?


At 11:32 AM 5/19/98 +0200, Jon Arne Hegge wrote:
>I'm working on a masters thesis in University of Oslo, and I'm 
>wondering if anyone have a link or document describing how to 
>use the support for QoS in IPv6? Spesifically how to set the 
>flow-label field and the class-field. Or is this up to the TCP/IP 
>stack? I have been looking at Winsock 2, because this project will be
>based on NT, and it contains support for some types of real-time traffic
>and multimedia transfer.
>The question is basically if the IPv6 spec. incorporates some standard for
>setting the values in these fields(flow-label & class-field)?
>Or maybe its an RFC I have missed..:) ?(RFC1363 comes to mind)

At the moment I don't believe there are any standards for the IPv6 Traffic Class and Flow Label field.

The basic presumption now in use for the IPv6 Traffic Class field is that it will follow work on the IPv4 TOS field.  This is why there is now a full 8-bits in the recently created Traffic Class field as opposed to the now defunct 4-bit Priority field.

The current IPv6 spec talks about this as follows:

>7.  Traffic Classes

>   The 8-bit Traffic Class field in the IPv6 header is available for use
>   by originating nodes and/or forwarding routers to identify and
>   distinguish between different classes or priorities of IPv6 packets.
>   At the point in time at which this specification is being written,
>   there are a number of experiments underway in the use of the IPv4
>   Type of Service and/or Precedence bits to provide various forms of
>   "differentiated service" for IP packets, other than through the use
>   of explicit flow set-up.  The Traffic Class field in the IPv6 header
>   is intended to allow similar functionality to be supported in IPv6.
>   It is hoped that those experiments will eventually lead to agreement
>   on what sorts of traffic classifications are most useful for IP
>   packets.  Detailed definitions of the syntax and semantics of all or
>   some of the IPv6 Traffic Class bits, whether experimental or intended
>   for eventual standardization, are to be provided in separate   documents.

>   The following general requirements apply to the Traffic Class field:

>      o  The service interface to the IPv6 service within a node must
>         provide a means for an upper-layer protocol to supply the value
>         of the Traffic Class bits in packets originated by that upper-
>         layer protocol.  The default value must be zero for all 8 bits.

>      o  Nodes that support a specific (experimental or eventual
>         standard) use of some or all of the Traffic Class bits are
>         permitted to change the value of those bits in packets that
>         they originate, forward, or receive, as required for that
>         specific use.  Nodes should ignore and leave unchanged any bits
>         of the Traffic Class field for which they do not support a
>         specific use.

>      o  An upper-layer protocol must not assume that the value of the
>         Traffic Class bits in a received packet are the same as the
>         value sent by the packet's source.

So the real place to learn what's going on with these bits is the new IETF Diffserv working group:


>If this is off topic here, I apologize.

Sending to the IPng list is the right place on protocol questions/topics ([email protected]).