From: DWINKWORTH@wi.rr.com
Date: Thu Aug 30 2007 - 11:31:16 ART
You should be fragmenting. You are absolutely right, you are shaping
at that rate and so packets will wait to be de-queued at that rate.
The actual serialization is irrelevant in this case.
----- Original Message -----
From: Scott Smith <hioctane@gmail.com>
Date: Thursday, August 30, 2007 8:56 am
Subject: frame-relay traffic shaping, fragmentation, port speed
To: groupstudy <ccielab@groupstudy.com>
> I'm hoping someone can shed some light on why my thinking is wrong
> on this.
>
> Config example: 2 512k PVCs on a T1 port. Each PVC is shaped via FRTS
> to 512k with no burst and the physical interface can run at T1 speed.
>
> Cisco says "you do not need fragmentation because the port speed is
> T1, irregardless of the shaping."
>
> I know all the in and outs of fragmentation/interleaving,
> serialization delay, etc and how this impacts voice traffic. Where
> I've got a problem is the seeming disregard for the amount of traffic
> that will actually pass through the interface. T1 port or not a single
> PVC cannot send more than 512k since it is shaped to that rate.
> Granted, once the traffic passes through shaper and its time to place
> the bits on the wire it'll be serialized at T1 rate (512k of traffic
> will be serialized at T1 rate) . Since a single PVC can only place
> 512k on the T1 port how is it that we completely ignore this fact when
> deciding to frag or not frag? It seems to me, in this case, the port
> speed is irrelevant because we can only send at 512k... OK, I
> could go
> on and on but I'll spare you all :-)
>
> So, obviously I'm wrong and or confused... lord knows it isn't the
> first time and will not be the last but I'd really like to know
> why my
> logic is flawed. Thus far no one who says I'm confused (including
> Cisco) has been able to explain why.
>
> TIA!
>
> --
> Scott
> CCIE #17040 (R&S)
>
>
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