Re: How many can administrative groups assigned?

[sven.van_den_bosch@alcatel.be]

Curtis,

I agree with you that the current interpretation is clear. It brings,
however, some difficulties regarding Forwarding Adjacency (FA) LSPs.
Suppose you have an LSP that includes gold as a resource class. It goes
through links A-B (gold), B-C (gold, north) and C-D (gold, south). Imho,
the current FA specification would make this a non-coloured FA-link, or
alternatively, it could be coloured gold. In both cases, depending on the
interpretation of uncoloured links, it could be used for an LSP that
specifies e.g. exclude north, which is not what you want. This problem is
due to the bitmask operation. We feel that at least one more TLV would be
needed (speciying the OR operation on the bit-mask for the FA-LSP). We will
document this in the next version of
draft-vandenbosch-mpls-fa-considerations-00.txt.

Sven.





Curtis Villamizar <curtis@workhorse.fictitious.org> on 08/05/2002 20:22:11
                                                              
                                                              
                                                              
  To:          Sven VAN DEN BOSCH/BE/ALCATEL@ALCATEL          
                                                              
  cc:          "Naidu, Venkata" <Venkata.Naidu@Marconi.com>,  
               "'???'" <jhyoung.kim@samsung.com>,             
               mpls@UU.NET, CCAMP <ccamp@ops.ietf.org>,       
               te-wg@ops.ietf.org                             
                                                              
                                                              
                                                              
  Subject      Re: How many can administrative groups         
  :            assigned?                                      
                                                              





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In message <OFB9A0B479.64961C82-ONC1256BB3.002CC49C@net.alcatel.be>,
sven.van_d
en_bosch@alcatel.be writes:
> Naidu, Kim,
>
> I think it depends a little bit on the interpretation. In principle the
> resource classes can be interpreted either as a bit mask (in which case
32
> 'base' classes can be defined) or as an integer value (in which case 2^32
> values can be used). Even with the bit mask interpretation, derived
> resource classes can be built by combining multiple non-mutually
exclusive
> 'base' classes (you could have 32 generic classes called 1, 2, 3 and so
on
> and then build your resource classes on top of those). The problem lies
of
> course in the processing of the resource class information. If they are
not
> used in a simple bitmask, an AND operation is not sufficient to determine
> the resource class of a link. Also, if a link would have multiple derived
> classes, different TLVs would be needed. It would make sense to expand a
> little bit on these issues in the appropriate documents. In my opinion,
> this is a general issue with the TE extensions, so it should be explained
> there.
>
> Sven.


The definitions are currently very clear.  What you have described
differs from the current definitions and therefore would not be a
clarification to the use of admin class but a change in semantics.

I do not know of anyone using more than a handful of admin class bits
and many who do not use them at all.  Lets not take any MPLS
capability and make it any more complicated than it needs to be or
introduce arbitrary change for no good reason.

Curtis