I think this is a terrible idea for several reasons.
1) MPLS is not a global solution - if it survives at all in the long
term, it will be limited to the core of large networks - and there is
therefore no real reason to drag its complex mechanisms up into the
simple IP layer. In particular we have IP-in-IP tunnel mechanisms,
so the complex extension header replacing the S bit is unnecessary.
2) If MPLS has one major virtue, it is the "MP" for Multi-Protocol.
This aspect is lost in the proposal.
3) Using the field currently called "flow label" to carry a swappable
MPLS-style label defeats the alternative use of this field as an end-to-end
field for QOS. The argument currently raging shows that the WG has no
consensus about this field, but there has been very little support for
an MPLS-like use. Indeed this was one of the options rejected at the
beginning of IPv6, when the CATNIP proposal was rejected. Some people
will tell you that is why MPLS was invented in the first place.
4) The blind mapping of the 3 bit "EXP" field into the traffic class field
makes no sense. In fact, as far as the EXP field has any meaning, it
is a compressed version of the traffic class field; writing this compressed
version back into the original field is useless.
Brian
[EMAIL PROTECTED] wrote:
>
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>
> Title : IPNGLS - IP Next Generation Label Switching
> Author(s) : V. Roesler et al.
> Filename : draft-roesler-ipngwg-ipngls-00.txt
> Pages : 17
> Date : 29-Aug-01
>
> This document proposes the forwarding of IPv6 packets using label
> switching techniques, with the same advantages of the Multiprotocol
> Label Switching (MPLS) architecture. The document proposes the
> mapping of all MPLS header fields into the IPv6 header, raising
> several advantages like the simplicity of the model, the decrease of
> overhead, and others. This mapping was called IP Next Generation
> Label Switching, or just IPngLS, and can work concurrently with
> MPLS, i.e. IPv6 packets are forwarded with IPngLS and IPv4 packets
> are forwarded with MPLS.
>
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-roesler-ipngwg-ipngls-00.txt
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