IOS 12.x: automatic DSP allocation for G.711ulaw/alaw transcoding?

[raziel78kain]

Hello,

we have several Cisco routers 28xx, with IOS 12.x; every router has an E1 ISDN (30 channels), and 2 PVDM2-16. Furthermore, in every router a SIP trunk is configured.

We have noticed that, in the routers where we have this configuration:

dial-peer voice x voip

...

codec g711ulaw

...

!

we can reach 30 ISDN/SIP calls.

Instead, where we have this configuration:

voice class codec 1

codec preference 1 g711ulaw

codec preference 2 g711alaw

!

dial-peer voice x voip

...

voice-class codec 1

...

!

we can reach only 16 calls.

Is it normal? Maybe the router automatically allocates some DSPs for a possible G.711ulaw/alaw transcoding?

TIA and regards.

[D_Lebedev]

Hi,

To say the truth PVDM2-16 not enough for make all Voice calls in your configuration i think.

"show dspfarm dsp all" will show you DSP allocation.

I've faced with same problem one time.

We had 3845 12.4T PVDM2-64......2 E1 PRI+CFB+XCODE 729*711.

I'd  add second PVDM2-64 for make all features work as need.

[raziel78kain]

I can assure you that we have had up to 30 calls in the first scenario (only g711ulaw configured), and up to 16 in the second one (both g711ulaw and g711alaw configured).

Anyone else has other ideas?

Regards.

[raziel78kain]

Hello,

we have just solved the issue.

We have noticed that, in the routers where we had this issue, the dial-peer 0 was matched.

Then, we have configured a correct VOIP dial-peer, so that this one is matched, and the issue has disappeared: now, we can have more than 16 calls.

So, the voice class codec wasn't the cause of the issue.

But anyone could explain us why we had the issue, when the dial-peer 0 was matched, please?

Regards.

[Roger Kallberg · Accepted solution]

When dial peer 0 is used the codec would be G729 and VAD would also be used. G729 is a higher complexity codec that G711, that's the reason for why you only could get 16 calls.

You should always take care to avoid using dial peer 0 and remeber VAD is BAD, so disable use of any codec with a "b" in the name.

Please remember to rate helpful responses and identify helpful or correct answers.

[raziel78kain]

Hello Roger,

thanks for your answer.

The weird thing is that the "show" commands normally used so far didn't help us to find the issue before.

In fact, here's the ouput from some previously submitted "show voice call status" and "show voice dsp voice" commands (when we had the issue):

----------

show voice call status

CallID     CID  ccVdb      Port        Slot/DSP:Ch  Called #   Codec    MLPP Dial-peers
0x93B46    534  0x47EDA468 0/0/0:15.4       0/5:6  *XXXXXX     g711ulaw       0/1
0x93B92    618  0x47EDA468 0/0/0:15.2       0/1:1  *XXXXXX     g711ulaw       0/1
0x93B94    61E  0x47EDA468 0/0/0:15.6       0/1:3  *XXXXXX     g711ulaw       0/1
0x93B96    624  0x47EDA468 0/0/0:15.8       0/1:4  *XXXXXX     g711ulaw       0/1
0x93B99    62A  0x47EDA468 0/0/0:15.9       0/1:5  *XXXXXX     g711ulaw       0/1
0x93BA2    648  0x47EDA468 0/0/0:15.7       0/5:2  *XXXXXX     g711ulaw       0/1
0x93BAA    660  0x47EDA468 0/0/0:15.13      0/5:5  *XXXXXX     g711ulaw       0/1
0x93BAE    66C  0x47EDA468 0/0/0:15.17      0/5:4  *XXXXXX     g711ulaw       0/1
0x93BB2    678  0x47EDA468 0/0/0:15.10      0/1:6  *XXXXXX     g711ulaw       0/1
0x93BB4    67E  0x47EDA468 0/0/0:15.14      0/5:7  *XXXXXX     g711ulaw       0/1
0x93BB6    684  0x47EDA468 0/0/0:15.15      0/5:8  *XXXXXX     g711ulaw       0/1
0x93BB8    68A  0x47EDA468 0/0/0:15.3       0/1:2  *XXXXXX     g711ulaw       0/1
0x93BBC    696  0x47EDA468 0/0/0:15.5       0/1:8  *XXXXXX     g711ulaw       0/1
0x93BC4    6AE  0x47EDA468 0/0/0:15.1       0/5:3  *XXXXXX     g711ulaw       0/1
0x93BCA    6C0  0x47EDA468 0/0/0:15.12      0/1:7  *XXXXXX     g711ulaw       0/1
0x93BD0    6D2  0x47EDA468 0/0/0:15.11      0/5:1  *XXXXXX     g711ulaw       0/1
16 active calls found

show voice dsp voice

C5510 001 01 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  02    0    2020/2227
C5510 001 02 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  03    0    2968/4590
C5510 001 03 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  06    0    1437/1623
C5510 001 04 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  08    0    1406/1491
C5510 001 05 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  09    0     842/1315
C5510 001 06 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  10    0    2321/3201
C5510 001 07 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  12    0    2611/5474
C5510 001 08 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  05    0    3543/7789
C5510 001 09 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 10 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 11 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 12 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 13 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 14 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 15 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 001 16 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 01 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  11    0    6388/7482
C5510 005 02 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  07    0      849/995
C5510 005 03 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  01    0    1428/2324
C5510 005 04 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  17    0      160/168
C5510 005 05 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  13    0      432/452
C5510 005 06 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  04    0    4746/6507
C5510 005 07 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  14    0    4014/4672
C5510 005 08 g711ulaw      24.3.5 busy  idle      0  0 0/0/0:15  15    0  10870/11911
C5510 005 09 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 10 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 11 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 12 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 13 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 14 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 15 None          24.3.5 idle  idle      0  0                 0          0/0
C5510 005 16 None          24.3.5 idle  idle      0  0                 0          0/0

----------

So, we thought that everything was OK (apart the fact that we had only 16 calls).

Could you help us to explain that, too?

Thanks and regards.