[Users] Best practice for DNS failover using OpenSER?

[T.R. Missner]

Greg,

This is a ref to SER. Apparently this functionality has been added to the
new pre-release version. I did find some talk about it in the release notes.
I couldn¹t find any specific documentation. Admittedly I don¹t understand
the layout of SER¹s site very well as I haven¹t spent much time there.

-- TR


On 1/15/07 8:33 PM, "Greg Fausak" <lgfausak at gmail.com> wrote:

> In the text below I quote Kerker 'SER does support DNS failover.'.
> Is this ser or openser?  Where can I read more about this?
> 
> -g
> 
> On Jan 15, 2007, at 10:40 AM, Klaus Darilion wrote:
> 
>>>>> 
>>>>> Staffan,
>>>>>  
>>>>> 
>>>>> 
>>>>>  
>>>>> 
>>>>> Kerker Staffan wrote:
>>>>>  
>>>>> 
>>>>> ...
>>>>>  
>>>>> 
>>>>>    
>>>>>  
>>>>>> Now, if I disable one of the Gateways, I hang every second call. OpenSER
>>>>>> does
>>>>>>  
>>>>>> 
>>>>>> not
>>>>>>  
>>>>>> 
>>>>>> try the second A record address if the first doesn't answer. How can I
>>>>>> solve
>>>>>>  
>>>>>> 
>>>>>> this? Shouldn't OpenSER fail over to the second A record listed in the
>>>>>> NAPTR
>>>>>>  
>>>>>> 
>>>>>> => SRV
>>>>>>  
>>>>>> 
>>>>>> resolving? Or will OpenSER continue to resend all SIP INVITES until
>>>>>> timers
>>>>>>  
>>>>>> 
>>>>>> fire? Would
>>>>>>  
>>>>>> 
>>>>>> it help if the proxy recieved an ICMP port/destination unreachable from
>>>>>> the
>>>>>>  
>>>>>> 
>>>>>> network? Is
>>>>>>  
>>>>>> 
>>>>>> there anyway to get around this? In the other direction, from POTS to
>>>>>> sip,
>>>>>>  
>>>>>> 
>>>>>> the PGW2200
>>>>>>  
>>>>>> 
>>>>>> nicely switches over to the second of my two OpenSER servers if I shut
>>>>>> one of
>>>>>>  
>>>>>> 
>>>>>> them down. These servers have the same DNS entries (but for another SIP
>>>>>> domain, NAPTR =>
>>>>>>  
>>>>>> 
>>>>>> SRV => 2x A record).
>>>>>>  
>>>>>> 
>>>>>>       
>>>>>>  
>>>>> Yes, OpenSER or for that matter every transaction stateful proxy should
>>>>>  
>>>>> 
>>>>> do RFC 3263 based fail-over. But as you can imagine this is pretty
>>>>>  
>>>>> 
>>>>> complex to implement and that's why openser does not support it yet, it
>>>>>  
>>>>> 
>>>>> is listed on the development roadmap. The newest release of SER does
>>>>>  
>>>>> 
>>>>> support DNS failover.
>>>>>  
>>>>> 
>>>>> 
>>>>>  
> 
> 
> 
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