From: Radoslav Vasilev (deckland@gmail.com)
Date: Mon Oct 02 2006 - 12:02:58 ART
Hi group,
Does the interleaving occur automatically once fragmentation is configured?
For the interface level fragmentation, DocCD says:
<docCD>
For interleaving to work, both fragmentation and the low-latency
queueing policy must be configured with shaping disabled.
</docCD>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hwan_c/ch05/hfrfrint.htm
As far as I understand this mode, it just applyes the same
fragmentation parameters to all DLCI's under an interface and yet I
thought when using fragmentation under a specific DLCI, interleaving
kicks in automatically (small packets are interleaved with the already
fragmented big packets).
Rado
On 10/2/06, Petr Lapukhov <petr@internetworkexpert.com> wrote:
> Let's talk a little bit more about FRF.12, leaving VoFR stuff aside :)
>
> To start with, there are two ways of configuring FRF.12 - per VC and at
> interface level.
>
> In both cases, important moment is that fragmentation occurs after
> dequeueing
> (but _before_ intereaving). And fragmentation decision is based solely on
> packet *size*, nothing else. (At least, on hardware platforms commonly
> encountered in CCIE lab, check out Chris Lewis' reply a bit later)
>
> Now, there is no way to _conditionally_ avoid packet fragmentation with
> FRF.12,
> even by putting them into any kind of priority queue. This has been
> discussed
> a few times, just a couple of references:
>
> http://www.groupstudy.com/archives/ccielab/200605/msg01632.html
> http://www.groupstudy.com/archives/ccielab/200605/msg01675.html
>
> To finish, let's just add that whole idea of fragmentation is connected to
> the
> concept of "interleaving" queue. With per-VC this is dual-FIFO at interface
> level.
> With interface level fragmentation it's unclear, but Cisco says it works :)
>
> HTH
>
> PS
> There is also exist "voice-adaptive" fragmentation, that turns on FRF.12,
> based on packets presense in priority queue. But it still uses packet size
> for fragmentation decision.
>
> 2006/10/2, Scott Morris <swm@emanon.com>:
> >
> > That depends on what you do with them. FRF11 is designed for VoFR, and
> > will
> > not fragment any VoFR frames. FRF12 is more generic in nature, and makes
> > no
> > specific delineation for voice or other packet types (IP is IP).
> >
> > However, if you have voice in a priority (LLQ) queue on the interface,
> > anything in the priority queue will bypass the entire fragmentation scheme
> > and is therefore unaffected. There are some previous posts regarding this
> > if you want to search the archives for a little more detail that may be
> > slipping my mind at the moment.
> >
> > HTH,
> >
> >
> > Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
> > #153, CISSP, et al.
> > CCSI/JNCI-M/JNCI-J
> > IPExpert VP - Curriculum Development
> > IPExpert Sr. Technical Instructor
> > smorris@ipexpert.com
> > http://www.ipexpert.com
> >
> >
> > _____
> >
> > From: sabrina pittarel [mailto:sabri_esame@yahoo.com]
> > Sent: Sunday, October 01, 2006 3:37 PM
> > To: Scott Morris; ccielab@groupstudy.com
> > Subject: Re: Q. on frame relay fragmentation
> >
> >
> > I see...
> > are then voice packets automatically excluded from fragmentation or should
> > I
> > manually set the fragment size to be bigger then the voice packets...is
> > the
> > this behavior different for different types of fragmentation (FRF.12
> > FRF.11
> > or cisco)?
> >
> > Sabrina
> >
> >
> > ----- Original Message ----
> > From: Scott Morris <swm@emanon.com>
> > To: sabrina pittarel <sabri_esame@yahoo.com>; ccielab@groupstudy.com
> > Sent: Sunday, October 1, 2006 11:23:10 AM
> > Subject: RE: Q. on frame relay fragmentation
> >
> >
> > Because it will introduce extra latency into the mix, and voice traffic is
> > latency-sensitive. So you don't want to have choppy voice.
> >
> > That and voice packets are typically small enough that it makes little
> > sense
> > to fragment them. Fragmentation is done to make all things play better
> > with
> > each other on slower speed links. And since voice (or SNA or some other
> > stuff) is generally the reason for fragmentation, it wouldn't serve much
> > purpose to fragment that traffic as well.
> >
> > HTH,
> >
> >
> > Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
> > #153, CISSP, et al.
> > CCSI/JNCI-M/JNCI-J
> > IPExpert VP - Curriculum Development
> > IPExpert Sr. Technical Instructor
> > smorris@ipexpert.com
> > http://www.ipexpert.com
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > sabrina pittarel
> > Sent: Sunday, October 01, 2006 2:17 PM
> > To: ccielab@groupstudy.com
> > Subject: Q. on frame relay fragmentation
> >
> > Hi,
> > I was reading about frame relay fragmentation and everywhere in the
> > documentation I read that voice packets should not be fragmented...
> > Why is
> > that?
> >
> > Sabrina
> >
> > _______________________________________________________________________
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>
>
>
> --
> Petr Lapukhov, CCIE #16379
> petr@internetworkexpert.com
>
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