From: Imal kalutotage (imal.kalutotage@gmail.com)
Date: Tue Nov 01 2005 - 02:17:26 GMT-3
Hi,
can somebody tell me how to calculate fragment size from the Bc..
Cheers
imal
On 11/1/05, Ralph <Mandela@myrealbox.com> wrote:
>
> Dave,
>
> The CiscoPress Book "IP Quality of Service" by Srinivas Vegesna, Has a
> good explanation and case study on frame-relay fragmentation. IMHO, I think
> this book does a good job explaining a lot of QoS topics.
>
> Ralph
>
> -----Original Message-----
> From: "Schulz, Dave" <DSchulz@dpsciences.com>
> To: "Ralph" <Mandela@myrealbox.com>
> Date: Mon, 31 Oct 2005 21:59:53 -0500
> Subject: RE: Re: Frame-Relay fragmentation
>
> Thanks for the great info, Ralph. Do you have any recommendations on
> the technical details of fragmentation. The doc CD is somewhat limited
> on this subject. Yes, fragmentation is fair game. Even though voice is
> not a part of the R&S exam, surely having the router/switch prepared for
> this, would be a viable test option.
>
>
> Dave Schulz,
> Email: dschulz@dpsciences.com
>
>
> -----Original Message-----
> From: Ralph [mailto:Mandela@myrealbox.com]
> Sent: Monday, October 31, 2005 7:36 PM
> Cc: Schulz, Dave; ccielab@groupstudy.com
> Subject: Re: Re: Frame-Relay fragmentation
>
> Dave:
>
> Using a Tc of 10ms is good for voice latency. Calculate the fragment
> size from the Bc value. If its greater than the average size of VOIP
> packets, VOIP should be transmitted unfragmented.
>
> HTH
> Ralph
>
> -----Original Message-----
> From: "Ralph" <Mandela@myrealbox.com>
> To: DSchulz@dpsciences.com
> Date: Mon, 31 Oct 2005 18:48:24 -0500
> Subject: Re: Frame-Relay fragmentation
>
> Hello Dave:
>
> FRF.12 does not discriminate betweeen voice and data. Particularly if
> it's VOIP (layer 3)and fragmentation being layer 2. If the fragment size
> is less than the average size of the VOIP packets they will all be
> fragmented. If the VOIP packets are less than the fragment size, just
> like any other type packet, they will be transmitted without being
> fragmented.
>
> On the other hand, FRF.11C does discriminate between voice and data. It
> does not fragment voice packets regardless of what fragmentation size is
> configured. But if I can recollect properly, FRF.11C is used only on
> DLCIs configured for VoFR, (layer 2). However, this form of
> fragmentation is not recommended for VOIP.
>
> As for the configuration of FRF.12, all you really need is the map-class
> frame-relay fragment command. It's also commonly used with the map-class
> frame-relay fair queue command; Probably can also be used with the
> map-class priority-group command - not very certain. After all
> fragmentation actually occurs at the TxQ.
>
> With Voice not being tested anymore in the Lab, do you think frame relay
> fragmentation is still something to be concerned with?
>
> HTH
> Ralph.
>
>
>
>
>
>
> -----Original Message-----
> From: "Schulz, Dave" <DSchulz@dpsciences.com>
> To: <ccielab@groupstudy.com>
> Date: Mon, 31 Oct 2005 17:04:56 -0500
> Subject: Frame-Relay fragmentation
>
> I was working through the doc CD, where it stated something about the
> FRF.12 inherently allows all voice traffic to pass-through unfragmented,
> while fragmenting the data packets to the specific length. So, can I
> assume that if a lab states to fragment all packets above 53 bytes (the
> default), and allow voice to be unfragmented....then you may simply
> configure "frame-relay fragment" command under the specific frame
> map-class or interface, along with the frame-relay traffic-shaping
> interface command?
>
> I almost want to believe that priority queuing is needed, but am
> confused on which way to go here (sometimes we make things more
> complicated then they really are). Thoughts?
>
>
> Dave Schulz,
> Email: dschulz@dpsciences.com <mailto:dschulz@dpsciences.com >
>
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