asterisk users - Jul 2005 - Enabling rtcachefriends prevents phones from calling each other

With rtcachefriends = yes in sip.conf, my SIP phone registered to Asterisk
Server A cannot dial another SIP phone registered to Asterisk Server B. The
error message is: "Cannot create channel of type SIP (Cause 3 - no route to
destination)".

The two phones _can_ call each other if I set rtcachefriends = no. The common
extensions.conf simply uses Dial(SIP/extension) to dial extensions.

Both Asterisk servers are using identical MySQL databases, kept in sync using
replication. The sipusers tables in both databases show the correct dynamic IP
address and port for both phones, indicating that the phones did register
successfully. And the dynamic registration information is reflected in both
databases because of the MySQL replication.

However, running "sip show peers" on Server A only shows the phone
registered to Server A. Running the same command on Server B only shows the
phone registered to Server B.

So despite the fact that phone B's registration data (IP address and port)
is in Server A's database, the Asterisk on Server A doesn't know how to
route the call to phone B. It looks like Asterisk is using cached data and
ignoring the database, but the registration info for phone B never got into the
cache.

I need rtcachefriends enabled, because I need MWI to work. I've seen this
problem discussed before, but I haven't come across a solution. Anyone have
an answer? Thanks in advance.

Rana Dutt
Softel Solutions, Inc.
rdutt@softelinc.com
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Star User wrote:
> So despite the fact that phone B's registration data (IP address and
port) is in Server A's database, the Asterisk on Server A doesn't know
how to route the call to phone B. It looks like Asterisk is using cached data
and ignoring the database, but the registration info for phone B never got into
the cache.
rtcachefriends is not designed for use in this way, it assumes it has 
_exclusive_ control of the database. If Server A makes _any_ reference 
at all to Phone B before it has registered to Server B, then Server A 
will have a cached "unknown address" for Phone B, expecting that it
will
later see a registration for Phone B. It will not ever look back into 
the database for Phone B's address until the cached record expires from 
memory.

Basically, you cannot cache records when you are sharing a database, 
unless the systems doing the caching are aware of each other and can 
tell each other when to flush and/or update their caches.

> Kevin P. Fleming wrote:
>> Matthew Boehm wrote:
>> Can't it be changed so that if Server A has stored an "unknown
address"
for
>> phone B that if it needs to contact B again it should look up in the
>> database to "try" and contact it instead of just giving up?
Perhaps
>> rtagressive option? Contact only, not storing info in cache.
> "Can" it be done? Of course, it's all just code :-)
> I think it would be reasonable to add that as an option, but the number
> of Realtime-related options is rapidly getting out of hand and people
> will not be able to understand what they all do and how they interact...
Please, please add this option. If you send me a patch, I will gladly
volunteer to test it thoroughly.

Having both MWI working and multiple servers working is a must for us.
Thanks much,

Rana Dutt