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New Member

Non-Traversal calls issues

 

Hello all,

I'm implementing some new Telepresence devices:
Site A
VCS-Control (X8.1)
VCS-Expressway (X8.1)
MCU 5310 (4.4)
C40 codec (7.0.2)

Site B
C20 codec (7.0.2)
Different subnet from site A

I've enabled H.323 & SIP on the VCS-C and have tested multiple calls between Site A & B. Whenever the calls go out H.323 to SIP, or SIP to H.323 from the C40 to the C20 or the other way around, there's no problem. Both sites receive video and audio.
Whenever I force the same protocol. i.e, H.323 to H.323 or SIP to SIP and make the same calls, site B (C20) doesn't get video from Site A (C40). However the C40 is receiving both video & audio from the C20. What's interesting is that if I make the same calls from the MCU, which is also at Site A, then there's no problem. So the problem is between the C40 and C20.
Since I'm not physcally at the sites because I'm doing this implementation remotely, I can only rely on the stats I get from the GUIs. I have attached a picture the customer took from the C20 screen. 

Calls:
Traversal calls
C40-C20 H.323-SIP - call ok
C20-C40 H.323-SIP - call ok

C40-C20 SIP-H.323 - call ok
C20-C40 SIP-H.323 - call ok
MCU-C20 H.323-H.323 - call ok

Non-Traversal calls
C40-C20 H.323-H.323 - No video received on C20
C40-C20 SIP-SIP - No video received on C20
C20-C40 H.323-H.323 - No video received on C20
C20-C40 SIP-SIP - no video received on C20

So it seems that there's only a problem on the C20 during non-traversal calls. I do not want to use a Traversal license between these 2 endpoints.

Thank you for your help. Any input would be greatly appreciated.

-Greg



 




 



 

Everyone's tags (1)
1 ACCEPTED SOLUTION

Accepted Solutions

When you do an H323 to SIP

When you do an H323 to SIP call, all media is "proxied" by VCS, so they would still work even if they can't ping each other.  When you do a non-traversal call, media flows directly between the endpoints.

To ping from a C-Series, login to the codec via SSH (same credentials as the Web browser) and type systemtools network ping 10.1.1.1

Where "10.1.1.1" is the IP address of the remote endpoint.
 

11 REPLIES

Most of the time this is a

Most of the time this is a firewall issue, either blocked ports or some layer3 feature

like ALG, incpection, helper, .... some features are enabled by default and are not even shown,

but you have to disable all things which would manipulate the signaling.

 

On non traversal calls huge range of udp and tcp ports needs to be open in between

both endpoints for media and signaling. Please check the manual and your local settings

for the exact value. If unsure try to allow >=1024 for udp and tcp in between these endpoints

and in between all other video components (like vcs-c, mcu, ...)

Please remember to rate helpful responses and identify

New Member

Thank you Nick and Martin,In

Thank you Nick and Martin,

In my post I made an error in putting a call from the MCU to C20 as Traversal. The MCU is at the same location as the C40, but on a different subnet. H.323 to H.323 calls between the MCU and C20 are fine.
By that I mean that the stats show tx & rx to the C20 from the MCU conference interface.

Since the MCU and C40 are at the same location and one works, but not the other, i didn't think it was a firewall issue. But now that I see that they are on different subnets, it's possible that something is blocking video.

-Greg

 

VIP Green

Hi Greg,As Martin has

Hi Greg,

As Martin has indicated, it is most likely a firewall issue (Blocked Ports, Packet Inspection, etc) - but also do not rule out other network infrastucutre either - ie, if your routers are doing any type of packet acceleration/WAAS/etc) these can cause issues too - you'll need to have bypass rules in for your TelePresence equipment.

Wayne
--
Please remember to rate responses and to mark your question as answered if appropriate.

Wayne
--
Please remember to rate responses and to mark your question as answered if appropriate.
New Member

Thank you Wayne,I just

Thank you Wayne,

I just unregistered both endpoints from the VCS-C and made IP to IP calls and they didn't work (either direction). However calls to the MCU which is at the same site as the C40, but one a different subnet went through. 

This is certainly a firewall issue since the VCS-C is not longer involved. I will have the customer check out the ports tomorrow. 

Thank you all.

-Greg

Did you actually confirm that

Did you actually confirm that the endpoints can ping each other?

New Member

Nick,No I didn't. I don't see

Nick,

No I didn't. I don't see a ping utility on the C series codec. The codecs can connect to each other on H.323 to SIP calls. 

-Greg

When you do an H323 to SIP

When you do an H323 to SIP call, all media is "proxied" by VCS, so they would still work even if they can't ping each other.  When you do a non-traversal call, media flows directly between the endpoints.

To ping from a C-Series, login to the codec via SSH (same credentials as the Web browser) and type systemtools network ping 10.1.1.1

Where "10.1.1.1" is the IP address of the remote endpoint.
 

New Member

Nick,You were right! The

Nick,

You were right! The systems can't ping each other. Thank you so much. Now i can present this to the customer and have them take a look.

I'll keep you updated.

Cheers!

-Greg

Glad to hear it - in my

Glad to hear it - in my experience, one way audio or video is more often than not a routing issue.

Please rate and/or mark answers as appropriate.

Further to what Martin has

Further to what Martin has said, this could actually be a bit simpler and just be a routing issue.

Does the C20 recieve audio?  If not, can the endpoints ping each other directly?

 This problem sounds symptomatic of everything being able to route to and from your "core" subnet where your VCS is, but other endpoints not being able to route all the way to the C20.  This is because a traversal call "proxies" all media via the VCS, so as long as everything can route to and from the VCS, it works fine. 

In a non-traversal call, the signalling goes via VCS which allows the call to establish, but then media flows directly between the endpoints, so if they can't route to each other you will see issues.

New Member

Nick,I confirmed with the

Nick,

I confirmed with the customer that the endpoints couuldn't ping each other. I don't totally know what caused the problem. They said that there was a small network switch between the C40 and wall jack. They removed the switch and now the calls 100% connect.

Thank you for your help!

-Greg

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