From: Volkov, Dmitry (Toronto - BCE) (dmitry_volkov@ca.ml.com)
Date: Tue Sep 03 2002 - 23:54:02 GMT-3
I agree with Chris, there is conception of channels carying voice and data
inside one DLCI - just found good link below:
<http://www.cisco.com/warp/public/788/vofr/fr_frag.html>
http://www.cisco.com/warp/public/788/vofr/fr_frag.htmlsecond
FRF.11 Standard
A Voice over Frame Relay (VoFR) implementation uses the FRF.11 to define how
voice and data are encapsulated on the Frame Relay DLCI. Thus, data, fax
signaling and voice use FRF.11 encapsulation when sent on a DLCI that
carries voice. FRF.11 mixes these traffic types on a DLCI by defining
sub-channels (identified by channel IDs) within the DLCI. Each sub-channel
has a header field that describes the frame payload type. Up to 255
sub-channels can be specified per DLCI.
Note: If DLCIs are not configured for VoFR, they will use standard Frame
Relay data encapsulation as specified by FRF.3.1.
thirdFRF.11 Annex-C Fragmentation
FRF.11 Annex-C fragmentation describes the way data is carried on an FRF.11
DLCI (configured for VoFR). FRF.11 Annex-C includes a fragmentation
specification for the data sub-channels.
Only frames with data payload type are fragmented. Frame Relay distinguishes
voice frames from non-real-time data frames because the FRF.11 payload
specifies the traffic type. Therefore, regardless of the voice frame size,
it bypasses the fragmentation engine.
-----Original Message-----
From: Chris Hugo [mailto:chrishugo@yahoo.com]
Sent: Tuesday, September 03, 2002 10:09 PM
To: Desimone, Aurelio; 'Volkov, Dmitry (Toronto - BCE)';
'ccielab@groupstudy.com'
Subject: RE: FR fragmentation and Voice
I believe you can run VOFR and Data. Here is a config that can make it
happen.
rb#sr Ser
interface Serial0/0
ip address 192.168.1.1 255.255.255.0
encapsulation frame-relay
no ip mroute-cache
frame-relay traffic-shaping
frame-relay interface-dlci 101
class voice
vofr cisco
map-class frame-relay voice
no frame-relay adaptive-shaping
frame-relay fair-queue
frame-relay voice bandwidth 24000
frame-relay fragment 80
"Desimone, Aurelio" wrote:
You are correct on your definitions but you can only run vofr by itself
under a pvc (you cannot carry vofr and data on the same pvc). In order to
enable vofr on a pvc you use 'vofr' under the frame-relay interface-dlci
(adding the 'cisco' keyword uses proprietary vofr encapsulation and
proprietary fragmentation). This is my understanding, anyway. Here are some
good links explaining the differences:
http://www.cisco.com/warp/public/788/voip/vofr_encap_frag_5733.html
http://www.cisco.com/warp/public/788/voip/vofr_encap_frag2_5733.html
http://www.cisco.com/warp/public/788/voip/vofr_encap_frag3_5733.html
Aurelio
-----Original Message-----
From: Volkov, Dmitry (Toronto - BCE) [mailto:dmitry_volkov@ca.ml.com]
Sent: Tuesday, September 03, 2002 1:32 PM
To: 'ccielab@groupstudy.com'
Subject: FR fragmentation and Voice
Can somebody! confirm or disprove the following:
definitions:
VoFR - voice packets directly encapsulated into L2 FR frames
VoIP - voice packets are encapsulated into L3 packets
To use FR fragmentation - FRTS has to be enabled.
FR Fragmentation is necessary :
1) PVC is not carrying voice (is not configured as VoFR, but may carry voice
as VoIP), but is sharing the link with other PVCs that are carrying voice
(these other PVCs may carry VoFR or VoIP)
OR
2) when PVC is carrying both voice and data (VoFR and VoIP/data).
================================
option 1) FRF.12 - is the recommended fragmentation to be used by VoIP
configuration: "frame-relay fragment [frag size]" under "map-class
frema-relay [class name]"
=================================
option 2) VoFR - is anabled by "vofr" undef "frame-relay interface-dlci"
command.
fragmentation FRF.11 Annex C is enabled in this case the same way as FRF.12
("frame-relay fragmen! t [frag size]" under "map-class frema-relay [class
name]")
CISCO proprietary fragmentation triggered by adding "cisco" after "vofr" :
"vofr cisco"
under option 2) only VoFR packets are NOT fragmented - all other including
VoIP packets may be fragmented
================================
What is the difference between FRF.11 Annex C and Cisco proprietary (with
exception of word "proprietary") ?
When better to use one and when other ?
Thank You,
Dmitry
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