From: Ralph (Mandela@myrealbox.com)
Date: Mon Oct 31 2005 - 21:36:22 GMT-3
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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