Re: [Ieprep] re-charter

[ken carlberg <[e-mail]>]

ok, then you are advocating a particular realization of EF as  
stipulated in rfc3246, as opposed to a new DSCP.  thanks for the  
clarification.

-ken


On Jul 15, 2005, at 4:25 PM, Janet P Gunn wrote:

>
>>
>> On Jul 13, 2005, at 5:19 PM, Richard F Kaczmarek wrote:
>>
>>
>>> <snip>
>>>
>>
>>
>>> With the Cisco routers we were using,
>>> we could allocate bandwidth in the EF queue for emergency
>>> communications
>>> and for normal traffic. In this latter case, some sort of marker
>>> (e.g.,
>>> DSCP) may be needed for emergency traffic, but a unique per hop
>>> behavior
>>> may not be needed.
>>>
>>
>> for this last sentence, if what you are advocating is defining
>> another DSCP value but with no distinctive corresponding per hop
>> behavior, then I think that is a non-starter.
>>
>>
>
>
>> From RFC 3246
>>
> "   Finally, it is possible to implement hierarchical scheduling
>    algorithms, such that some non-FIFO scheduling algorithm is run on
>    sub-flows within the EF aggregate, while the EF aggregate as a  
> whole
>    could be served at high priority or with a large weight by the top-
>    level scheduler.  Such an algorithm might perform per-input
>    scheduling or per-microflow scheduling within the EF aggregate, for
>    example. "
>
> This is one way of describing the functionality above.
>
> Also from RFC 3246
> "It should be noted that it is quite acceptable for a Diffserv domain
>    to provide multiple instances of EF.  Each instance should be
>    characterizable by the equations in Section 2.2 of this
>    specification.  The effect of having multiple instances of EF on  
> the
>    E_a and E_p values of each instance will depend considerably on how
>    the multiple instances are implemented.  For example, in a multi-
>    level priority scheduler, an instance of EF that is not at the
>    highest priority may experience relatively long periods when it
>    receives no service while higher priority instances of EF are  
> served.
>    This would result in relatively large values of E_a and E_p.  By
>    contrast, in a WFQ-like scheduler, each instance of EF would be
>    represented by a queue served at some configured rate and the  
> values
>    of E_a and E_p could be similar to those for a single EF instance."
>
> And at the San Diego meeting, one of the authors of RFC 3246 (sorry, I
> forget who) explicitly said in his presentation that there was  
> never any
> intention to restrict EF to a single DSCP.
>
>
> There do, of course, remain issues as to whether it is a good idea  
> or not.
> But it is permissible under RFC 3246.
>
> Janet
>
>


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