Hello Muhammad,
Your approach is the correct one (from SIP perspective) IMHO. But there are
questions on the implementation side too - like the "Super Node" is just a
storage or it should have SIP capabilities? How much of this behavior should
be hardcoded in the registrar + usrloc module ?
Best regards,
Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com
On 04/05/2013 04:57 AM, Muhammad Shahzad wrote:
Well at 5 am in the morning while thinking on this topic the only thing
ringing in my mind is a mechanism similar to IP to IP Gateway. Here is the
main concept.
1. We have number of SIP servers running, say sip1.mydomain.com,
sip2.mydomain.com ... sipN.mydomain.com, each serving domain mydomain.com
and a SIP client A can select any one of these servers through DNS look-up
(or whatever way possible) and registers to that server. Lets call these
servers as Base Nodes.
2. Upon successful registration of client A to server sip1.mydomain.com,
this Registrar Node fires an Event, which can be subscribed by a back-end
SIP server, lets call it Super Node. This event will only contain following
things,
a). User part of all Contact URIs of client A with Expiry.
b). Registrar Node information e.g. its IP address + Port.
c). SIP domain of client A. (in case of multi-domain setup)
3. Super Node stores this information in some db back-end (memcache, redis,
mysql etc.). This is sort of back-to-back register process but without SIP
or authentication, since that has already been handled on Based Node anyway.
The Super Node only needs to know which user is registered on which Base
Node e.g. user 1001 is registered on node sip1.mydomain.com, user 1203 is
registered on sip6.mydomain.com and so on.
4. When a SIP client B tries to send INVITE or MESSAGE or SUBSCRIBE to SIP
client A. The SIP request will arrive on Base Node it is currently
registered with, say sip2.mydomain.com. This node will first do local
look-up for location of client A. Upon failure it will forward request to
Super Node, which will do a look-up on Event database and finds that client
A is registered on node sip1.mydomain.com, so it will send SIP redirect
response 302 to requester Base Node. Now the request source node knows the
address of request destination node, where it will send request next and
they both, while acting as independent SIP servers, establish SIP session
between caller and callee. This should work regardless if both nodes serve
same or different SIP domains.
5. The Super Node will also give us global presence of all users currently
registered to all Base Nodes, which may be useful for management and
monitoring etc.
Pros:
1. Completely independent of network topology and SIP.
2. Will work seamlessly for multi and federated domains.
3. Scale-able in every direction.
4. Minimal overhead for session establishment. Once supper node return
destination base node address in SIP redirect response, session will
establish directly between source and destination base node. Further
optimizations are possible, e.g. base node can cache destination base node
returned by supper node for any particular user and avoid querying super
node for recurring SIP sessions.
Cons:
1. Well, the key problem i can guess is of course the Event database size
and speed, as it will have information on every user registered to every
Base Node. I suggest memory cache db such as Redis would be idle for this
storage.
2. Bandwidth consumed in Event transport. We can apply compression and make
event queues as optimization.
Comments and suggestions are highly welcome.
Thank you.
On Thu, Apr 4, 2013 at 2:05 PM, Vlad Paiu<vladp...@opensips.org> wrote:
Hello all,
We would like to get suggestions and help on the matter of distributing
the user location information.
Extending the User Location with a built-in distributed support is not
straight forward - it is not about simply sharing data - as it is really SIP
dependent and network limited
While now, by using the OpenSIPS trunk, it is possible to just share the
actual usrloc info ( by using the db_cachedb module and storing the
information in a MongoDB cluster ), you can encounter real-life scenarios
where just sharing the info is not enough, like :
- NAT-ed clients, where only the initial server that received the
Register has the pin-hole open, and thus is the only server that can relay
traffic back to the respective client
- the user has a SIP client that only accepts traffic from the server
IP that it's currently registered against, and thus would reject direct
traffic from other IPs ( due to security reasons )
We would like to implement a true general solution for this issue, and
would appreciate your feedback on this. Also we'd appreciate if you could
share the needs that you would have from such a distributed user location
feature, and the scenarios that you would use such a feature in real-life
setups.
Best Regards,
--
Vlad Paiu
OpenSIPS Developer
http://www.opensips-solutions.com
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--
Mit freundlichen Grüßen
Muhammad Shahzad
-----------------------------------
CISCO Rich Media Communication Specialist (CRMCS)
CISCO Certified Network Associate (CCNA)
Cell: +49 176 99 83 10 85
MSN: shari_78...@hotmail.com
Email: shaherya...@googlemail.com
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