per-class bandwidth accounting and class-type

["Choudhury, Sanjaya" <Sanjaya.Choudhury@marconi.com>]

	Hi! I have some basic questions related to the issue of bandwidth
accounting 
	for diff-serv classes.

	I am trying understand, why I need to define a class-type (which is
trying to
	define some sort of "super' class over standardized diffserv
classes) to solve
	 the IGP scalability issue.

	Can't the problem be solved by user configuration ? For example:

		1. User configures LSRs in his domain, with the diff-serv 
		classes he needs, along with the bandwidth limits for those
		classes.

		2. Advertising the per-class bandwidth information via IGPs

		    a) If the domain administrator wants to use the most
granular
		        per-class information to be used by the IGPs in his
domain 
		        (and have enough bandwidth) then
				all the per-class bandwidth for all the
classes 
				defined in the LSR can be advertised.

		    b) If the domain administrator wants the LSRs to support
the
		        diffserv classes he configured in step1 , but wants
the to
		        reduce the amount of IGP traffic generated to
exchange 
		        the per-class bandwidth information then

				i) he can configure his domain to advertise 
				the per-class bandwidth information for a
sub-set
				of the classes he defined in the step1.
Bandwidth
				information for rest of the classes can be
combined
				with the aggregated bandwidth information.

		  3. Similarly, if wants to define only two pre-emption
priorities per-class
		     in his domain, he can always configure his domain
appropriately.
		
		     All these can be defined, by a MIB (or some policy
database) and
		     user has control over what he wants.

	Am I missing something ? Your help will be appreciated.

	Thanks,
	sanjay