The MPLS WG Archive

["Sasha Vainshtein" <sasha@iprad.co.il>]

______________________________________________
With best regards,
Sasha Vainshtein
mailto: sasha@iprad.co.il
phone: +972-3-7659993 (office)
fax:      +972-3-6487779 (office)


>>-----Original Message-----
>>From: owner-mpls@UU.NET [mailto:owner-mpls@UU.NET]On Behalf Of
>>Daniel N. Bauer
>>Sent: Monday, November 27, 2000 12:04 PM
>>To: Sasha Vainshtein
>>Cc: mpls@UU. NET
>>Subject: Re: E-LSP or L-LSP
>>
>>
>>> >>For an E-LSP, the aggregate bandwidth is known. This
>>aggregate bandwidth
>>> >>corresponds to the sum of bandwidths that are requested for
>>each PHB class
>>> >>that are carried inside the E-LSP. In case that the
>>distribution of the
>>> >>PHB classes is known, then admission control could be carried out.
>>> >>In networks where resources are pre-allocated per PHB class
>>> >>and where this is done consistently on all LSR, then the distribution
>>> >>of the pre-allocated resources can be used to carry out
>>admission control
>>> >>per E-LSP.
>>> >>
>>> >>For example, consider the following distribution:
>>> >>EF gets 5%, AF1.x gets 10%, AF2.x gets 20%, AF3.x gets 20%, AF4.x
>>> >>gets 20%;
>>> >>meaning that on a 100Mbit/s link, EF could reserve up to 5
>>> >>Mbit/s, AF1.x up
>>> >>to 10Mbit/s, etc. etc.
>>> >>
>>> >>If now an E-LSP requests 7 Mbit/s and this E-LSP carries EF,
>>> >>AF1.x and AF3.x
>>> >>traffic, then the 7 Mbit/s could be split up and assigned to
>>the classes
>>> >>as follows:
>>> >>EF - 1 Mbit/s
>>> >>AF1.x - 2 Mbit/s
>>> >>AF3.x - 4 Mbit/s
>>> >>according to the 'weights' of the resource distribution.
>>> >>Then, admission control for each class could be done
>>seperately. The E-LSP
>>> >>could be admitted if all of the admission control checks succeed.
>>> >>
>>> >>Does this sound reasonable?
>>
>>> Sorry, to me it does not - please consider the case when you do
>>not need any
>>> more LSPs carrying EF traffic in this LSR.
>>
>>I don't understand what you mean here. Maybe you could give an example?

The examples I have in mind are based on the naive understanding of the
"weighted" per E-LSP admission rules.
Example 1: Bandwidth on the link is pre-allocated like you have said (i.e.,5
MBit/s for EF, 10 Mbit/s for AF1 etc.).  However, "all" the  5 Mbit/s of the
EF traffic in this node as well as, say 1 Mbit/s of AF1 and  1 Mbit/s of AF3
go to the same destination. Such a flow could be satisfied by a 7 Mbit/s
E-LSP with appropriate admission rules - but these rules cannot, to the best
of my understanding,  be derived from the overall distribution of capacity
of the egress link.
Example 2: Two 25 Mbit/s E-LSPs are requested, one carrying EF and AF3, the
other one carrying EF and AF4. According to the "relative weights" logic, up
to 5 Mbit/s would be admitted to each of the two E-LSPs, with the total
exceeding the overall 5% limit on EF.
Hopefully these examples will be helpful.
>>
>>Thanks,
>>
>>-Daniel
>>