Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
New Member

Configuring FRF.12

Hi!

I'm having some problems with a FRF.12 configuration. I have 2 Frame-Relay PVCs (one for VoIP and the other for data). The VoIP PVC has a 48Kpbs CIR. the data PVC has 640Kbps CIR and a 704Kbps PIR. Here goes tha FR class-maps:

################################

map-class frame-relay DataClass

frame-relay adaptive-shaping becn

frame-relay cir 704000

frame-relay bc 14080

frame-relay mincir 640000

frame-relay fair-queue 1024 16 2 600

frame-relay fragment 1000

#################################

map-class frame-relay VoIPClass

no frame-relay adaptive-shaping

frame-relay cir 48000

frame-relay bc 960

frame-relay mincir 48000

frame-relay fair-queue

frame-relay fragment 1000

frame-relay ip rtp priority 16384 16383 48

#################################

Thanks in advanced,

Olindo

6 REPLIES
Cisco Employee

Re: Configuring FRF.12

What is th issue here? These look OK, except that I would set the fragment size to 80 bytes ont the 48kbs Voip PVC.

New Member

Re: Configuring FRF.12

Hi!

Thanks for your answer. My question focus mainly on the caculation of the fragment size. Should it be by the CIR PVC or the phylical link Bandwith? Waht if we had 4 PVCs?

Regards,

Olindo

New Member

Re: Configuring FRF.12

The fragment size is generally calculated on the PVC Speed.

The fragment size is also dependant on the real time packet interval.

For Example, If you have a 64 Kb PVC most would set the fragment size to 80 bytes. This is probably the best way to do it. Generally 80 bytes for every 64Kb. Sometimes it is also necessary to figure in the real-time packet interval which is the time it takes a packet to traverse your WAN. The method of calculating the RPI is about 80 bytes for every 10ms above the standard 10ms delay. For examole, If you have the same 64Kb pvc and your delay is roughly 30 ms you would end up with a fragment size of 240 bytes. Initially you have the standard 80 bytes for a 64Kb pvc w/10ms delay, in this case your delay is 20ms over the standard 10ms which amounts to 160 bytes. I hope you get the jist of things.

Everything I spoke about above can be found in the Cisco Press book entitled CISCO VOICE over FRAME RELAY, ATM, and IP edited by Seve McQuery. The ISBN is 1-57870-227-5.

I hope this helps.

New Member

Re: Configuring FRF.12

Hi!

Thanks for your help. That answered my question.

Best regards,

Olindo

New Member

Re: Configuring FRF.12

hi Olindo

i am just about to do a very similar configuration, and i was wondering whether you have this working correctly?

if so - do you have to always set the fragmentation-size at both ends of the PVC?

for us - we have the following scenario:

head-office -to- remote site (A) has 2 PVC's: 1 to be used for VoIP only, and the other for other data.

Currently - i have an access-list on the VoIP PVC that only allows traffic to the particular source/destination of the VoIP routers.

We can't change the fragmentation-size because the IOS's on the routers do not support them, and while planning for an upgrade i was wondering whether i would need to set the fragmentation size on all other remote-sites that have data PVC's into the head office?

(the head-office has 14 PVC's in total out of the same physical serial interface).

I'd be grateful for any tips from your experience with this!

New Member

Re: Configuring FRF.12

Hi there!

Yes, i have it working. Yes, you have to implement FRF.12 (fragmentation) on both sides of the PVC or else you won't have IP passing trough. Both sides have to know how to reassemble fragmented packets.

Regards,

Olindo

189
Views
0
Helpful
6
Replies
CreatePlease to create content