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Author Topic: RTP traffic bringing the network down - HELP!  (Read 403 times)

radiodan

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RTP traffic bringing the network down - HELP!
« on: December 13, 2020, 08:47:00 AM »

Hello,

Got a serious issue with RTP traffic bringing down a network which I need to get sorted ASAP!.

Setup is as follows:

Draytek Vigor2927 at site 1, linked to another Draytek Vigor2927 at site 2 via a LAN to LAN IPsec VPN. VPN is working as it should and both sites have strong internet connections.

Need to transfer streaming audio from site 1 to site 2. This is done with a hardware IP audio codec that sends the data to another IP audio codec (decoder). Audio data transfer is via the RTP protocol at around 1.5mbps - well within the capabilities of the internet and VPN connections.

Within a few seconds of the IP audio codecs turning on and transferring data, the Vigor 2927's lockup and ALL lan and WAN traffic stops. Basically, the 2927 is killed by this RTP data transfer, as if it is getting "swamped" just like a DoS attack.

Testing both the encoder and decoder at the same site on the same LAN, all is ok. So basically it appears that the VPN is the issue? What is most concerning however, is the fact that the Vigor2927 can be brought to its knees like this - no good for a critical network environment!!

I have checked and run through settings, including the firewall, but to no avail.

Any ideas? Don't want to have to rip these new 2927's out if I can help it!

Thanks!
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tubaman

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Re: RTP traffic bringing the network down - HELP!
« Reply #1 on: December 13, 2020, 11:10:55 AM »

Assuming the firmware is up to date (latest 4.2.0.2) I'd be getting in touch with Draytek and requesting a fix - especially as the 2927 appears to be a recent model. Clearly a bad bug in there somewhere.
 :(
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d2d4j

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Re: RTP traffic bringing the network down - HELP!
« Reply #2 on: December 13, 2020, 11:33:16 AM »

Hi

Have you turned of SIP.  If not, you need to turn off SIP

Many thanks

John

Enable the First Priority for VoIP SIP/RTP:
      SIP UDP Port:
5060
(Default:5060)
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d2d4j

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Re: RTP traffic bringing the network down - HELP!
« Reply #3 on: December 13, 2020, 11:59:52 AM »

Hi

Sorry, it was SIP ALG I was meaning, so I think now Draytek no show this option, so you need to telnet as follows:

telnet to daytek

check SIP ALG status - sys sip_alg ?

if enabled, you need to disable - sys sip_alg 0

save changes - sys commit

reboot draytek - sys reboot

To enable SIP ALG telnet to draytek and run sys_alg 1, then save and reboot

This is because SIP ALG does not play nicely with NAT

Many thanks

John
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radiodan

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Re: RTP traffic bringing the network down - HELP!
« Reply #4 on: December 13, 2020, 10:28:33 PM »

SIP ALG is currently turned off - this can be done from the GUI..

Have submitted a support ticket with Draytek UK.

Thanks.
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