I have a network with an Asterisk server that I need to terminate SIP trunks on. As I understand it, I need to open ports
UDP 5060 (SIP)
UDP 10000-20000 RTP (audio) data

I've set up the SIP (UDP 5060) port in the NAT section of the firewall, forwarding all traffic on port 5060 to the Asterisk PBX. But what's the correct configuration for the RTP ports? On a 2920 there doesn't seem to be any way to configure such a large range of ports in the NAT forwarding.

How have people done this? What's the correct configuration for an inbound SIP trunk on a 2920n?

I have just looked at the Live Web Demo of the 2920n at draytek.com

Similar to most Draytek Products, under NAT > Port Redirection, choose a number and you can set a large port range, such as the 10000-20000 you require.

Hope this helps,

Neal.

If you are referring to setting the Mode to Range, then that doesn't actually do what you might think. While that mode does allow you to enter a range of ports, it then distributes those ports over a range of IP addresses. So for example, if I enter a port range of 10000-10002, a private port of 10000 and a private ip of 10.0.0.10, then
external port 10000 -> 10.0.0.10 port 10000
external Port 10001 -> 10.0.0.11 port 10000
external Port 10002 -> 10.0.0.12 port 10000

This isn't what I need. I want all of the ports in the range I specify to be directed to a single IP address. So I want:
external port 10000 -> 10.0.0.10 port 10000
external Port 10001 -> 10.0.0.10 port 10001
external Port 10002 -> 10.0.0.10 port 10002 etc

I have been able to do this with other routers, I can't see a way to achieve that with a 2920, because there are only 20 'slots' in the port redirection table, and even if I were willing to enter 1,000 entries, the router doesn't have room for them all. The 'range' mode doesn't do what I need.

I can't believe this would be impossible on such a high quality device, so I am prepared to accept that I may be approaching this problem from the wrong angle. I'm interested to hear from anyone who has terminated a SIP trunk through this router and how they achieved it.

Hi

I've not set an Asterisk system up and I've not used a 2920, but in the 2820, as well as there being a port redirection feature, there is also an open ports feature (both these features are in the NAT menu) and that does permit a range of ports to be opened up to one internal IP address (which sounds a bit more like what you're looking for). If I understand your requirements correctly, you could likely set the open ports range as 10000 - 20000 for 10.0.0.10 to make that work.

My understanding is that the port redirection facility is really for translating port numbers, though it can also be used to 'open' a single port per IP address by setting the public port and private port to the same number.

Bri