[Users] SIP clients and DNS SRV

Bogdan-Andrei Iancu bogdan at voice-system.ro
Thu Oct 27 10:34:29 CEST 2005


Hi Zen,

i see here two issues:
    1) for clients supporting SRV lookup - they must perform it for 
every sent request. To eliminate the gaps due registration, use 
replication of the registered contact on all the servers.
    2) for clients with no SRV support, Linux-HA or vrrp (or something 
based on single IP mask) should be the solution.

regards,
bogdan

Zen Kato wrote:

>Hi,
>
>If we set 'Use DNS SRV: Yes' and 5 minutes REGISTRATION interval
>on BT101(1.0.7.11) and GXP2000(1.0.1.9),these UACs can successfully
>Re-REGISTER and INVITE other UACs on time period B, which comes 
>after ser1 stops, every UACs changed their target from first 
>DNS SRV(sip1) to second DNS SRV(sip2). But during time period A
>if caller is not Re-REGISTERed on sip2, when he dials some number, 
>there is 'no tone(white tone?)' this means the server is down. 
>If the caller's phone is Re-REGISTERed on sip2 and callee's
>is not yet Re-REGISTERed on sip2 in the time period A, the caller's
>phone displays "404 not found". So, this is first 5 minutes out of
>service probabilty time. 
>
>After the operator of servers room knew that sip1 went down and
>sip2 is take care of sip calls, he tries to repair sip1 and
>restarts 'ser(openser)' on sip1. But all INVITEs are handled on 
>sip2 now. BT101s and GXP2000s never automatically go back to sip1. 
>So, the operator must stop sip2 untill all REGISTERs move from 
>sip2 to sip1.
>This is the second 5 minutes out of service probability time.    
>
>So, (5+5)minutes out of service probability time exist.
>If we set 60 minutes(default) for REGISTRATION interval,
>and all Re-REGISTERs happen on 50 minutes after sip1 down,
>(50+50)minutes out of service probabilty becomes high.
>
>stop ser1                stop ser2
>    |                       |
>    V                       V
>....|<-- 5 min-->|<--sip2-->|<-- 5min -->|<--sip1--.....->
>    |service stop|service   |service stop|service 
>    |            |continue  |            |continue
>time|<----A----->|<---B---->|<----C----->|<----D---.....->
>
>Do we need another backup method like Linux-HA if UACs(ONE
>outgoing line only devices) don't support DNS SRV?
>
>Regards,
>
>Zen
>
>------------ quote from Daniel's question -----------
>Daniel-Constantin Mierla daniel at voice-system.ro
>Wed Oct 26 16:46:32 CEST 2005
>
>I do not get the question regarding the out of service interval when the 
>client does not support srv. How you computed the 5+5 interval?
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