ATA NO AUDIO

[Sabbah]

Platform is V3001 Analog with built-in 4x FXO and 2x ATA interfaces. NBX is configured with VLAN tagging = 124.

I have installed 2x ATA at remote sites to communicate over IP. Both remote ATAs show "IP Online" on the NBX. When I use remote ATAs to call IP phones at the Main Site, call goes with no problem. Same also if I dial the extension of AA (ext. 500). The issue is only in the following cases:

If I call from Remote ATA to Remote ATA (both are on the same VLAN and IP subnet). There is no Audio in both directions.

When I call from remote ATA to NBX built-in ATA and vise versa, over the IP link. There is no Audio in both directions, called ATA rings, and when goes off-hook no audio.

When I call from remote ATA to NBX built-in FXO (to catch a PSTN line) and vise versa, over the IP link. There is no Audio in both directions, but call signalling establishes.

Only when I call from remote ATA to Main site IP phone, and vice versa, communication is successful and audio flows in both directions.

 What can be the problem? If it is networking problem, then why does remote ATAs to IP Phone work succssfully? Also, why are the two remote ATAs can not hear audio from each other, although they are on the same L2 VLAN and L3 IP subnet? I have attached some captured data from remote ATA console when calling from ATA-to-ATA (both remote), and when calling from ATA-to-PSTN as well as when calling from ATA-to-AA (this is successfully establishes). Also, I have attached wireshark dump data (I have mirrored the network interface where the remote ATA is connected). Please help. (Looks like I am not able to attach logs files)

[merlin215]

What happens if you remvoe the Vlans ? Using the default Vlan can you talk between the ATA's ? 

Also , I cannot viewe the data unless you have a case open with Us .  Sorry ...

what version of NBX code as well ? 

[Sabbah]

NBX V3001 Analog 6_5_22

Here are updates from my yesterday visit to the customer:

Somehow, remote ATAs can now call each other with no problem (I have NBX configured for Voice VLAN tagging with VLAN ID 124, and I have enabled "IP VLAN Tagging"). In such configuration, will the built-in analog card respond to ARP requests on the voice vlan? Will ARP replies from the analog card go tagged with voice vlan tag?

Remote ATA to the built-in ATA (or FXO ports on the analog PSTN gateway built-in card) still runs without audio.

I have traced the problem and found that the cisco switch, which is the responsible also for routing traffic between the voice and data subnets, can not get successful ARP information of the built-in analog ports. When I do a "show arp", I can see the IP address leased by the analog port from the built-in analog card, but the MAC address shows "incomplete".  I can see all built-in analog ports (2x ATA and 4x FXO) all share the same mac-address but with a number after the MAC address (from 1 to 6). Has anybody faced a problem with ARP in similar setup? I searched for an option to change the mac-address of individual analog ports, or to assign an IP address to each individual analog port, but I could not. Looks like the built-in analog card is treated as a whole. I will try tomorrow to replace the cisco switch with a Layer-3 3com switch and see if it can successfully capture the ARP data from analog ports.

[merlin215]

Somehow, remote ATAs can now call each other with no problem (I have NBX configured for Voice VLAN tagging with VLAN ID 124, and I have enabled "IP VLAN Tagging").

In such configuration, will the built-in analog card respond to ARP requests on the voice vlan?

Yes as the card does not change how it reacts to network protocols via changing tagging or vlans . 

Will ARP replies from the analog card go tagged with voice vlan tag?

Tagged meaning Priority Layer 2 or Layer 3 ( 802.1Q or 802.1P )  , no as its only audio packets that are tagged for priority .  

Remote ATA to the built-in ATA (or FXO ports on the analog PSTN gateway built-in card) still runs without audio.

Looks like the built-in analog card is treated as a whole. I will try tomorrow to replace the cisco switch with a Layer-3 3com switch and see if it can successfully capture the ARP data from analog ports.

Please send me your email address and I will send you a document describing network considerations on an nbx network . Explains a lot of how we work on the network . 

Are you familiar with our tagging and our vlan protocols ?

vlan id = vlan id of the vlan chosen to use for all nbx devices

 vlan tagging = 802.1Q 

IP vlan tagging = 802.1P

Note ALL changes described here require a reboot of the NBX after changes are made and reboot of all telephones as well , so as to reload and downlaod all NBX devices with the new info - ie  tags and vlan id info  from the NBX 

[Sabbah]

The port where the NBX is connected at the cisco switch is configured as trunk with pvid vlan 134 (I am using this vlan for accessing NBX Web management) and tagged vlan 124 (which is the voice vlan). When remote IP ATA calls an IP phone, that IP phone sends all traffic tagged with voice vlan id 124 (including ARP requests and replies), and that is why the call from remote IP ATA to the IP phone is successful. However, this is not the behavior of the built-in analog card. I have found that the ARP requests from the built-in analog card are untagged (while my network design requires that all traffic from this card should be tagged with voice vlan id 124, including the ARP requests/replies). This behavior causes the built-in analog card ARP requests to arrive at the wrong cisco VLAN interface, and get filtered. This is the log of this event from the cisco switch:

"IP ARP req filtered src 172.16.124.67 00e0.bb39.5abf, dst 172.16.124.67 0000.0306.0903 wrong cable, interface Vlan134"

"IP ARP req filtered src 172.16.124.67 00e0.bb39.5abf, dst 172.16.124.10 0000.0000.0000 wrong cable, interface Vlan134"

In the above log "172.16.124.67" is the IP address taken "On-The-Fly" by the built-in analog card PSTN port, when I made a call from the remote IP ATA, whereas "172.16.124.10" is the IP address of the cisco switch Interface VLAN 124 (voice vlan). As you can see, this ARP goes over untagged VLAN 134 instead of tagged VLAN 124 (voice vlan).

After these results, I had to re-design my network VLANs and IP addressing. Now the NBX is connected to a cisco switch interface that is: Trunk, which allows VLAN 124, and PVID 124 (Voice VLAN).

After this network re-design I have tested calls from remote IP ATA to one of the ATAs of built-in analog card: Call establishes successfully with normal two-way audio.

Tested Call from remote IP ATA to PSTN port of built-in analog card: The first test call went successful with 2-way audio, however all successive calls I have tried are strangly looped back to the remote IP ATA (I can hear my voice coming from the other end, it is like I am talking to myself, some how there is a loopback created causing my transmitted voice to bounce back to me and I hear it from receiver!!! Has anybody experienced such a situation??).

I have tested the reverse direction by calling from the PSTN to the remote IP ATA, calls are successful with normal audio.

So looks like situation is better, with the exception of calls from remote IP ATA to PSTN ports of built-in analog card, which end up with looped-back audio towards IP ATA. Any recommendations on this part?

My e-mail: mohamed.sabbah@gmail.com

[merlin215]

Not sure why arps are causing the issue . Arps only occur during the discovery process at layer 2 for the ata . After the discovery , the card should send all traffic via vlan 124 ( or the tagged vlan )as it gets the vlan form the downloaded info after the system is rebooted after changes made to the vlan id . .

Are you saying that control packets and audio  packets are not tagged correctly ? In both directions , we don't control what interface is used . All we do is tag appropriately .  I am not a Layer 3 expert , however it seems that a loop may have been inadvertantly created somehow . You may want to talk to someone weiht more routing experience than the voice forum . 

[Sabbah]

Well, Arps occur each time the built-in analog card port gets an IP-On-The-Fly  address to be able to communicate with the remote IP ATA. Those ARPs from the built-in card are untagged, unlike the ARPs from IP phones in similar situation, where all IP phones traffic is tagged (including ARPs).

My issue now: The switch port where the NBX connects, should it be link-type access vlan 124 (access port in the voice vlan without tagged traffic), or should it be trunk port with default untagged vlan "pvid" 124 (voice vlan) so that the untagged ARPs still go over the voice VLAN. This is too much confusing, and things would have been  much easier if management and telephony applications on the NBX were completely seperated (on the network level).

[merlin215]

Checking on this now . Stand By ....

[merlin215]

The NBX must always be on an untagged port . Day 1 issue .....

[Sabbah]

Issue of "Looped-back" audio is solved. Changing the Pulse dialing from ON to OFF on the PSTN analog port configuration fixed the issue. Now everything works as planned. Special thanks for Merlin for great support.

One Question: ATA 3C10120, is it supported on software 6.0.63 and 6.5.22?