nanog mailing list archives

Re: FR Tidbit [was: 56k modems/frame/ptp revisited (LONG)]


From: scott w <scott () digisle net>
Date: Tue, 1 Sep 1998 20:22:22 -1000 (HST)



Hello Dan,

I was speaking from a specific vendor's implementation point of view and,
as such, I should not have responded on the NANOG list.  Let's take this
to a private conversation as it's most likely not appropiate here.  I'll
respond to you privately.

In a parting shot for the rest of the crew, though, past experiences did
not give me that "touchy feely" sensation of getting all that was paid
for...  Oversubscription is guesswork at best!

scott


On Wed, 2 Sep 1998, Dan Jones wrote:

Scott,

      I'm curious.  Is your assertion that "CIR is guaranteed only under
"normal" conditions" based on the Frame Relay spec or a paticular vendor(s)
implementation?  I ask because I have been in that very debate for some
time (usually with a FR vendor justifying lousey performance).

      My tendancy is to take the "Comitted" in CIR literally.  It's my
understanding that the FR congestion management routines (at least the
Stratacom one - Foresight?) will only back off bursty PVC to the point
where it's <= CIR.  The implication then is that you'll always get at least
CIR - which makes sense since that's what you're paying for. 

Dan 



At 08:45 AM 9/1/98 -1000, scott w wrote:



On Tue, 1 Sep 1998, Scott, Dan wrote:

[snip]
line and port, but the important parameter is the committed information
rate
you purchase from the carrier.  Most of Sprint's frame relay business may
[snip]
from 0-56kbps.  Can purchase 56kbps CIR, but it costs extra, would need
[snip]

CIR is guaranteed only under "normal" conditions.  You won't get it under
heavy congestion.  Find out the MIR configured for your PVC.  I don't know
if they will tell you though...

scott







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