From: Ron Royston (ccie6824@xxxxxxxxxxx)
Date: Thu Nov 01 2001 - 14:14:32 GMT-3
The default Tc is not 142ms, the max is 125ms, the min is 10ms. For
non-realtime data, 125 ms is fine. To ensure a 125ms Tc, just set your Bc
the same as your CIR which forces the router to use the max supported Tc
value, 125ms. Be is calculated as Bits/Interval. Your map-class should be:
> map-class frame-relay test
> Frame-relay cir 48000
> Frame-relay bc 48000
> Frame-relay be 8000
> frame-relay mincir 16000
This tells your router to transmit 6000 bits per Tc (125ms) an average, or
CIR, and to burst to a max of 8000 bits per Tc, or 64000kbps. Once a BECN
is recieved, throttle back to 16000 bits per second (mincir, like cir, is
taken as /second).
<><><><><><><><><><><><><>
Ron Royston
Avnet Enterprise Solutions
http://www.nsd.avnet.com/
>From: "Yadav, Arvind K (CAP, GECIS)" <Arvind.Yadav@gecis.ge.com>
>Reply-To: "Yadav, Arvind K (CAP, GECIS)" <Arvind.Yadav@gecis.ge.com>
>To: Eddie <guitardudez@yahoo.com>, ccielab@groupstudy.com
>Subject: RE: Frame-Relay Traffic Shaping (FRTS)
>Date: Thu, 1 Nov 2001 06:08:16 -0500
>
>Please find the relation b/w Bc, Be, Tc
>
>Committed Information Rate (CIR) Rate (bits per second) the frame relay
>provider guarantees for data transfer. CIR values are set by the Frame
>Relay service provider and
>configured by the user on the router.
>Note: The port / interface access rate can be higher than CIR. The rate is
>averaged over a Tc period of time.
>Committed Burst (Bc) Maximum number of bits the frame relay network commits
>to transfer over a Committed Rate Measurement Interval (Tc).
>Tc = Bc / CIR.
>Excess Burst (Be) Maximum number of uncommitted bits the frame relay swit
ch
>attempts to transfer beyond the CIR over the Committed Rate Measurement
>Interval (Tc).
>Committed Rate Measurement Interval (Tc) Time interval over which Bc or
>(Bc+ Be) bits are transmitted. Tc is calculated as Tc = Bc / CIR. The Tc
>value is not directly
>configured on Cisco routers. It is calculated after the Bc and CIR values
>are configured. Tc cannot exceed 125 ms.
>Backwards Explicit Congestion Notification (BECN) A bit in the Frame Rela
y
>frame header that indicates congestion in the network. When a Frame Relay
>switch recognizes
>congestion, it sets the BECN bit on frames destined for the source router,
>instructing the router to reduce the transmission rate.
>
>
>Regds
>Arvind
>
> -----Original Message-----
> From: Eddie [mailto:guitardudez@yahoo.com]
> Sent: Thursday, November 01, 2001 12:14 PM
> To: ccielab@groupstudy.com
> Subject: Frame-Relay Traffic Shaping (FRTS)
>
> Here is the lab question:
> 1. Your service provider has a policy to mark all
> traffic exceed 48 K with DE bit. BECN will be sent.
> 2. Your service provider will discard all traffic
> exceed 64 K.
> 3. You have decided perform traffic control as
> follows. When receive a BECN, lower the speed to 16K.
> You must use Map Class with CIR, Be, Bc, MINCIR to do
> this. Measuring interval is 125ms.
>
> Here is my guess at a config from Caslow-p812:
>
> Int s0
> Frame-relay traffic shaping
> frame-relay interface-dlci102
> class test
> map-class frame-relay test
> Frame-relay cir 64000
> Frame-relay bc 8000
> Frame-relay be 16000
> frame-relay mincir 48000
>
> My questions are:
>
> 1) How do I change the measuring interval from the
> default of 142 to 125ms
> 2) Is this enough to trigger when I receive a BECN or
> do I need to apply the map-class to the interface?
> 3) I am confused as to how the cir, the bc, and the be
> relate to each other.
> Thanks in Advance.
>
> Regards,
>
> -Eddie
>
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