Here's what I got from a Networkers presentation.
FRF.12 allows for both UNI and end-to-end fragmentation. With FRF.12 UNI,
frames are reassembled on ingress to the network, in other words at the
service provider's switch. Frames cross the network unfragemented. The UNI
frame format looks like: Fragmentation Header/Frame Relay Header/Payload
(Fragment)/FCS. FRF.12 UNI is often sufficient to handle the problem of
large frames taking a long time to leave the router, thus causing a backup
for small voice frames or frames for interactive or real-time applications.
Last I heard, Cisco didn't support FRF.12 UNI, though. That could have changed.
With FRF.12 end-to-end fragmentation, frames traverse the network as
fragments and are reassembled at the terminating router. So both routers
would have to support it. The frame traverses the complete network looking
like this: Frame Relay Header/Fragmentation Header/Payload (Fragment)/FCS.
FRF.11 Annec C also does fragmentation. It is end-to-end. The difference is
that Annex C allows for a subframe header which supports many different
channels. The frame looks like: Frame Relay Header/Subframe
Header/Fragmentation Header/Payload (Fragment)/FCS.
As you can see from the frame formats, you have to be careful to configure
the routers (and switches) properly, obviously.
Priscilla
> > -----Original Message-----
> > From: John Neiberger [mailto:[EMAIL PROTECTED]]
> > Sent: marted́ 19 dicembre 2000 00.07
> > To: [EMAIL PROTECTED]
> > Subject: Frame Relay Fragmentation
> >
> >
> > I need to turn on FRF.12 on a remote router so that I can
> > make use of the
> > frame-relay ip rtp priority command. However, the PVC that I'll be
> > implementing that on connects to a router that cannot do FRF.12.
> >
> > Does FRF.12 need to be configured on both ends? It seems
> > that it probably
> > only needs to be configured on the end doing the fragmenting,
> > which would be
> > good news, but it I'm not positive about this. Will the near
> > end need to be
> > configured for FRF.12 so it knows how to reassemble those frame relay
> > frames?
> >
> > I'm guessing that I only have to do it on the end doing the
> > work, but I
> > wanted to check before I go break something on a production box. :-)
> >
> > Thanks as always,
> > John
________________________
Priscilla Oppenheimer
http://www.priscilla.com
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