Forgot CC on this one..... -----Original Message----- From: Helge Waastad Sent: 26. oktober 2005 13:56 To: 'Zen Kato' Subject: RE: [Users] SIP clients and DNS SRV Hi, You know, even if DNS SRV works fine, you will have problems with NAT'ed clients behind firewalls. Ther reason is that the session is opened between the server handeling the registration and the UAC. If this on crashes, the second one will never be able to send INVITE to the UAC since there is no open session through the firewall. Yes, you will see service unavaliability up to the registration interval, depending on the UAC functionality. The only solution for this is a (outbound) proxy cluster using Linux-HA (or vrrp) and a IP address take-over. (Or a Border Controller, but these are not for free..) Cisco 7960 works fine (also snom) I've seen that Sipura in 3.1.5 release also supports dns srv for redundancy/failover, but I have'nt tried it. -----Original Message----- From: Zen Kato [mailto:zenkato@pis.bekkoame.ne.jp] Sent: 26. oktober 2005 13:45 To: Helge Waastad Cc: klaus.mailinglists(a)pernau.at; users(a)openser.org Subject: Re: [Users] SIP clients and DNS SRV Hi, I posted on [serusers] regarding DNS SRV,t_replicate,backup server and GS phones. My test resut of BT101(1.0.7.11-newest) and GXP2000(1.0.1.9) was no good. My question is eventhough we set up DNS SRV on server side, if sip clients does not suppot DNS SRV, do we have a risk of (5+5)minutes out of service time when we set up 5 minutes REGISTER intervals? If UA have multiple REGISTERs outgoing lines such as GXP2000, we could set up Line1 for sip1&sip2(DNS SRV) Line2 for sip3 server. In this case if line1 does not work, the user can use Line2. Xlite can register 3 sip servers, but only default sip proxy can use as outgoing line, so the Xlite users have (5+5)minutes out of service risk. Does Cisco 7960 work perfectly on DNS SRV? Regards, Zen Helge Waastad wrote :