From: alsontra@hotmail.com
Date: Mon Feb 16 2004 - 21:36:26 GMT-3
Hi Andrew,
If you already haven't, you should read internetworkexperts FRTS slides.
They are top notch and contain quite a few detailed examples.
http://www.internetworkexpert.com/resources/01700368.htm
Alsontra
----- Original Message -----
From: "Edwards, Andrew M" <andrew.m.edwards@boeing.com>
To: <ccielab@groupstudy.com>
Sent: Monday, February 16, 2004 2:17 PM
Subject: Re: FRTS question
> Alright,
>
> I have looked through the IPexpert slide show discussion, read solie PS
> I, Caslow 2nd Ed., and even looked on CCO but I'm seeing what appear to
> be inconsistencies on the way FRTS is explained, particularly Be... and
> also implementing FRTS successfully by interpreting the given
> requirements.
>
> So I have a 2 part question....
>
> First, how does Be relate to the interval? Specifically, here is how I
> have seen it explained:
>
> - I have seen Be operation discussed as Bc tokens depleted in the
> interval then the router can use up to Be tokens within the current
> interval. After that, no more Be can be sent during remainder of ALL
> intervals for the bit rate period. IOW, Be tokens are depleted over the
> ENTIRE BIT RATE PERIOD, not per interval.
>
> - I have also seen Be operation discussed as Bc tokens depleted in the
> interval then the router can use up to Be tokens within the interval.
> After that, Be tokens are replenished for the next interval. This
> behavior occurs over ALL intervals for the bit rate period. IOW, Bc
> token settings are valid per interval.
>
> Can someone please expound upon which one it is?
>
>
> The second question relates to recommended methodologies to 'interpret
> FRTS requirements'. I will use the following 2 simplified examples of
> how to interpret requirements, the first is my understanding (looking
> for confirmation from peers) and the second is looking for how my peers
> would interpret these requirements.
>
> First -
>
> My understanding is that by definition of Bc and Be being per interval,
> it would seem that they are tokens being replaced per interval over the
> bit rate period. Thus, a simple frame relay R1 @ 128Kbps circuit
> guaranteed at 64kbps to R2 @ 64kbps circuit guaranteed to 32kbps would
> be:
>
> R1: CIR=128000, Bc=8000, Be = 8000, mincir = 64000, adaptive BECN
> R2: CIR=64000, Bc=8000, Be=0, mincir=32000, adaptive BECN
>
> Is this correct?
>
> Second -
>
> If I have a hub and spoke FR topology, R1 is hub, R2/R3 are spokes. R1
> has serial interface that operates at 1.544Mbps to provider. R2 is
> serial interface with 64Kbps to provider and R3 is serial interface with
> 128Kbps to provider. I know that I have a committed information rate
> from the provider on R2 at 32kbps and R3 at 64kbps.
>
> How would I go about setting up FRTS at R1 to ensure I do not exceed
> remote or local settings? Or, suffice to say, would I need more
> information about R1s provider CIR?
>
> Any thoughts or additional links are appreciated.
>
> andy
>
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