ma-voice quality

[a.helou]

I'm using VOIP (from a non cisco provider) over the WAN (leased line),I configured the serial interface as follows:

interface Serial1/0

bandwidth 128

no ip address

encapsulation frame-relay

frame-relay intf-type dce

!

interface Serial1/0.1 point-to-point

description voice

bandwidth 80

ip address 192.168.1.1 255.255.255.252

traffic-shape rate 80000 8000 8000 1000

frame-relay interface-dlci 100

!

interface Serial1/0.2 point-to-point

description data

bandwidth 48

ip address 192.168.3.1 255.255.255.252

traffic-shape rate 48000 7968 7968 1000

frame-relay interface-dlci 101

I devided the interface to 2 subinterfaces :one for voice packets and the other for data.

I'm experiencing some problems on the telephones (discontinous dialogue) when I run the PC anyware Application or an ACCESS replication.

The results of the show interface s1/0 shows :

Antelias#sh inter s1/0

Serial1/0 is up, line protocol is up

Hardware is PowerQUICC Serial

MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,

reliability 255/255, txload 93/255, rxload 65/255

Encapsulation FRAME-RELAY, loopback not set

Keepalive set (10 sec)

LMI enq sent 24364, LMI stat recvd 24364, LMI upd recvd 0, DTE LMI up

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

LMI DLCI 1023 LMI type is CISCO frame relay DTE

Broadcast queue 0/64, broadcasts sent/dropped 8122/0, interface broadcasts 0

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 2d19h

Queueing strategy: fifo

Output queue 0/40, 18275 drops; input queue 0/75, 0 drops

5 minute input rate 33000 bits/sec, 52 packets/sec

5 minute output rate 47000 bits/sec, 52 packets/sec

1862064 packets input, 194092712 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

1 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

1989966 packets output, 161007854 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

I noticed that I have the problem even when I just have one call only.

[s-doyle]

I would only suspect the codecs that you are using. If you are using G711 then you need more bandwidth for voice.

[pacameron]

The traffic shaping is not optimised for VOIP applications. You need to use frame relay traffic shaping, not the generic traffic shaping that is currenlty applied. You need to apply Low latency queueing to match on the voip traffic and prioritise it. Finally, you need to fragment the traffic at layer 2 to allow the smaller voip packets to be interleaved between the upper layer fragments. Have a look at the following URL for some background -

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_configuration_example09186a0080094af9.shtml#intro

When setting up the LLQ, it would be useful to know the specific UDP port numbers the application is using so this can be configured in the access list that matches on the traffic types.

cheers

Paul Cameron