Re: FRTS & DE

From: MADMAN (dave@interprise.com)
Date: Mon Apr 14 2003 - 12:23:51 GMT-3

   I work for a frame relay provider and you are correct Chuck, I can't
think of a sitution in which you would want to set the DE bit, it is a
function of the frame switch to flag packets when there IS congestion.

   The primary problem is if you flag a packet DE and lets say you have
a T1 with 768K CIR. By flagging a packet DE at the CPE You have just
eliminated the use of the CIR bandwidth! This is not the way to perform
QOS!!

   Dave
>
> Juan,
>
> I've never worked on the FR service-provider side of things, but I've heard
> that it's not a good idea to mark your frames with DE. Logically it makes
> sense to pick what kind of traffic you'd like to lose first, as you could
> then define a big committed burst and get away with it. But apparently many
> FR switches on the service provider side don't like seeing frames arrive
> from the CPE already marked with DE. They may get dropped even if no
> congestion occurs. Hopefully someone from the FR SP side of things will
> chime in with more details.
>
> Chuck Church
> CCIE #8776, MCNE, MCSE
> Wam!Net Government Services
> 13665 Dulles Technology Dr. Ste 250
> Herndon, VA 20171
> Office: 703-480-2569
> Cell: 585-233-2706
> cchurch@wamnet.com
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> jfaure@sztele.com
> Sent: Monday, April 14, 2003 5:36 AM
> To: ccielab@groupstudy.com
> Subject: FRTS & DE
>
>
> Hi all:
>
> I've some doubts about the Frame Relay Traffic Shaping operation. I've read
> a cisco doc named "Configuring Frame Relay Traffic Shaping" and I don't
> understand very well how the router "shapes" and drops packets when it
> receives BECN's events.
>
> If you see this doc, it seems that if any becn is received, the traffic
> rate is decreased by 25 percent. Then the system continues to drop with
> each BECN until you reach MINCIR, where it stops. And then, once the
> traffic rate has decreased, it must allow 16 time intervals of receiving no
> Becn before starting to increase traffic again.
>
> My question is: What about the packets transmitted and marked with DE bit?
> When and how the router starts to set the DE bit? Do you must configure the
> router with "frame-relay de-list" and "frame-relay de-group" to achieve
> this DE marking? Or the router can mark with DE without explicitily
> specifiying this and then these commands are only used to specify witch
> type of traffic do you prefer be maked first?
>
> Any help would be apreciated.
>
> Regards
>
> Juan Faure Ferrer
> email: jfaure@sztele.com
>
> Lmnea de Negocio de Telematica y CC
> Ingeniero de Integracisn de Redes y Sistemas
> ----------------------------------------------------------------------------
>
> SOLUZIONA TELECOMUNICACIONES
> Servicios Profesionales de UNION FENOSA
> Jerez, 3
> 28016 MADRID
> tel 91 579 30 00 fax 91 350 72 83
> ---------------------------------------------------------------------------
>
> 

-- 
David Madland
CCIE# 2016
Sr. Network Engineer
Qwest Communications
612-664-3367

I would rather have a German division in front of me than a French one 
behind me."
--- General George S. Patton

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