[28165] in North American Network Operators' Group
Re: UBR at MAE-East ATM, anyone?
daemon@ATHENA.MIT.EDU (Alex Rubenstein)
Tue Apr 18 13:19:11 2000
Date: Tue, 18 Apr 2000 13:09:35 -0400 (Eastern Daylight Time)
From: Alex Rubenstein <alex@nac.net>
To: Kevin Oberman <oberman@es.net>
Cc: nanog@merit.edu
In-Reply-To: <200004181654.JAA18087@ptavv.es.net>
Message-ID: <Pine.WNT.4.05.10004181256100.948-100000@kerplewie.nac.net>
MIME-Version: 1.0
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Errors-To: owner-nanog-outgoing@merit.edu
On Tue, 18 Apr 2000, Kevin Oberman wrote:
> Alex,
>
> your description of how the MAE ATM NAPs work is not quite in line
> with either my understanding or the ATMF traffic management specs.
I'm not surprised, as I may not know what I am talking about :)
> As you state, the connections to the NAPS is ABR, but you then say
> "with PCR being twice SCR". If the connection is ABR (and it is), there
> is not PCR or SCR. There is only MCR (minimum cell rate). This really
> means that you are guaranteed that the bandwidth reserved by the
> MCR will be available to you. Any traffic beyond this is treated on a
> best-effort basis, exactly as if it was UBR. The only limit on what
> you may inject (above MCR) is the line rate and there is no guarantee
> that any of this traffic will make it through the fabric.
I thought it was strange also, however my information comes from Wcom:
<snip>
> 3) is it still VBR, or UBR/ABR now?
It's actually implemented as ABR, with the peak cell
rate enforced and set to twice the reserved rate.
</snip>
