02-20-2002 08:32 AM - edited 03-12-2019 02:30 PM
I'm currently using g729r8 on a cisco mc3810 w/ a frame-relay 128K cir.. with a nortel key system.. no ip phones.. so i guess. you could say VoIP over FR .. my question is.. we have bad delay, static, and echo problems.. we are upgrading to t1's.. but do you suggest to keep the same codec?.. i've heard g711 is good.. any suggestions
02-20-2002 09:03 AM
G711 probably won't help, it would require too much bandwidth, it sounds like a QoS problem, do you have any QoS configured ?
check out this link.
02-20-2002 09:12 AM
You have told nothing about QoS in your network. While echo is NOT caused by a VoIP network, the existing echo can indeed become worse, more annoyable, because of delay. I don't think your problem is the codec, but it seems to me that there's no queue, fragmentation, interleaving and prioritization set in your network.
02-20-2002 09:54 AM
Voice has priority... the precedence is 5
02-25-2002 09:42 AM
Giving precedence won't solve your problems on a low bandwidth frame link. My suggestion would be to implement low latency queuing with frame relay traffic shaping and frame relay fragmentation. check out this link:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t2/dtfrpqfq.htm
02-25-2002 04:09 PM
Can you please give an example of your map-class for the frame and are you doing any QOS other than setting the IP precedence to 5. I would suggest using LLQ to priortize the voice traffic over the data. Are you doing any fragmentation. Go ahead and post the configs for you serial interface and the map-class and we will try to help you. Assuming you are doing no header compression g.729 is 24k a call and g.711 is 80k a call. I don't think g.711 will help.
Thank you,
-Mckee
02-26-2002 01:03 PM
It doesn't seem you need Low Latency Queuing (LLQ) since you only need to priviledge voice transmission (you are not worried about the different classes of data traffic, are?). So I'd suggest:
- LFI - Link Fragmentation and Interleaving
- RTP prioritization (priority queue)
- RTP header compression (this is not essential, but would save you kbps)
- WFQ - Weighted Fair Queue for everything that is NOT RTP
In do this in my network, and the performance is pretty good. Here's an example configuration of my routers (only the essential commands are listed):
interface Serial0/0
bandwidth 384
encapsulation frame-relay
frame-relay lmi-type ansi
frame-relay traffic-shaping
!
interface Serial0/0.1 point-to-point
bandwidth 384
frame-relay class SUBSCRIBER
frame-relay interface-dlci 101 CISCO
frame-relay ip rtp header-compression
map-class frame-relay SUBSCRIBER
no frame-relay adaptive-shaping
frame-relay cir 384000
frame-relay bc 3840
frame-relay be 0
frame-relay fair-queue
frame-relay fragment 480
frame-relay ip rtp priority 16384 16383 256
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