We have a tenant who has been having issues with a congested connection and in trouble shooting it we've noticed that there seems to be a lot of SIP traffic even when none of the phones are doing anything. We've determined that this traffic is mostly INFO packets generated by setting qualify=2000. I understand that 2000 ms is the default value for the qualification parameter but what I'm unclear on is exactly what the purpose of having asterisk qualify the phones is. I know that in a NAT situation, qualifications can help keep UDP sessions open in the firewall but in our case most phones are not behind NAT. I realize qualifying phones is also how asterisk keeps track of who is available for things like BLF but surely it doesn't need to do that every 2 seconds to keep the BLFs reasonably current. So I guess my question is what is the real purpose of the qualify setting in a non-NAT situation and can one safely set the qualification as something higher. I'd think something like 15 seconds would be more than enough for BLFs and the like. Chris
On Wed, Sep 15, 2010 at 8:20 PM, Chris Owen <owenc at hubris.net> wrote:> > We have a tenant who has been having issues with a congested connection and in trouble shooting it we've noticed that there seems to be a lot of SIP traffic even when none of the phones are doing anything. > > We've determined that this traffic is mostly INFO packets generated by setting qualify=2000. ? I understand that 2000 ms is the default value for the qualification parameter but what I'm unclear on is exactly what the purpose of having asterisk qualify the phones is. > > I know that in a NAT situation, qualifications can help keep UDP sessions open in the firewall but in our case most phones are not behind NAT. > > I realize qualifying phones is also how asterisk keeps track of who is available for things like BLF but surely it doesn't need to do that every 2 seconds to keep the BLFs reasonably current. > > So I guess my question is what is the real purpose of the qualify setting in a non-NAT situation and can one safely set the qualification as something higher. ? I'd think something like 15 seconds would be more than enough for BLFs and the like. > > ChrisTry it without qualify=yes. I have had phones setup over VSAT links and qualify=yes was a problem. Ping times averaged ~700ms from Equinix to Baghdad, but with packet loss and a wide range (jitter) in ping times, I constantly had phones jumping between "Reachable" to "Unreachable" I kept upping the value of the qualify statement which helped, but I finally just dropped it because everything was on the same subnet, and OpenVPN subnet. It worked just fine besides high jitter buffers and people needing an understanding that there would be a delay so they wouldn't step on each other as they spoke. Thanks, Steve T
Chris Owen <owenc at hubris.net> writes:> So I guess my question is what is the real purpose of the qualify > setting in a non-NAT situation and can one safely set the > qualification as something higher. I'd think something like 15 seconds > would be more than enough for BLFs and the like.The purpose is simply to see if the phone is available. For your particular use it is likely best to simply turn it off completely. If a phone disappears, its registration will eventually time out anyway. /Benny
One of the main benefits of qualify=yes is to detect network problems with peers. We send a lot of calls via a service provider using SIP but we have qualify-yes set so that if it becomes unreachable the dial fails immediatly without having to wait for a timeout which enables us to seamlessly failover to an ISDN connection. Chris Owen wrote:> We have a tenant who has been having issues with a congested connection and in trouble shooting it we've noticed that there seems to be a lot of SIP traffic even when none of the phones are doing anything. > > We've determined that this traffic is mostly INFO packets generated by setting qualify=2000. I understand that 2000 ms is the default value for the qualification parameter but what I'm unclear on is exactly what the purpose of having asterisk qualify the phones is. > > I know that in a NAT situation, qualifications can help keep UDP sessions open in the firewall but in our case most phones are not behind NAT. > > I realize qualifying phones is also how asterisk keeps track of who is available for things like BLF but surely it doesn't need to do that every 2 seconds to keep the BLFs reasonably current. > > So I guess my question is what is the real purpose of the qualify setting in a non-NAT situation and can one safely set the qualification as something higher. I'd think something like 15 seconds would be more than enough for BLFs and the like. > > Chris > > >