[Asterisk-Users] Re: load balancing 20 asterisk servers

[Chris Albertson]

DNS based load ballancing has it's place, as dose using an
application level switch.  

Say an earthquake takes out your California data center.
Shortly the DNS servers will notice and pull that center's
record.  However do to caches and all this is not fast
and users will notice.

What the switch does is route at the protocol level between
local machines.  You can take a machine off line and no one
will notice.  Works great until the big quake a backhoe
takes out a fiber cable ro there is a fire flood or who
knows what.

protocol level switches have to "know" about the protocol.
You can buy them that work with HTTP, HTTPS and the common ones
but I wonder aboit SIP?  Getting the RPT to the right * server
would be hard beetrer to have a proxy tell the user which *
server to go to and nothave to route RTP.


--- Miguel Ruiz Velasco Sobrino <miguelrvs at yahoo.com.mx> wrote:

> --- asterisk-users-request at lists.digium.com wrote:
> 
> 
> > The DNS approach does not handle single or multiple system
> failures,
> > only very elementary load balancing over a lengthy period of time.
> 
> Are you shure of that? I'm aware that the load criteria is trickier,
> but very possible.
> 
> If you use DDNS (dynamic DNS) using Bind 9. You have to run a health
> monitor (like a tcp
> or ping monitor) in one server (like the dns one) if one server dies,
> a script removes
> it's A record automagically from the pool, and even with a script
> that monitors the load
> you can dynamically add and remove the entry of each individual
> server in the DNS server.
> And you would not need to care if the load balancer sends the SIP
> stream to one server
> and the RTP stream to an other or in the case of outgoing connections
> or whatever
> extrange situation.
> 
> Use "nsupdate" utility for doing DDNS, it's really simple and
> incredibly powerfull. Also
> because all the requests are digitally signed, you will likely don't
> have security
> problems.
> 
> ------------------------
> 
> > You may want to consider a simpler aproach, why don't you balance
> the load via DNS?
> > If you put in a zone file various A records for the same machine,
> but with different
> > IP's, BIND will catch the trick and send a different IP (from the
> pool yo defined) each
> > time a DNS request arrives. That's a simple way of doing that, it
> will definively work
> > for termination, but you may have to think more who to cope with
> origiation (outgoing
> > calls), since different clients will be connected to different
> servers.
> > 
> > 
> > --- asterisk-users-request at lists.digium.com wrote:
> 
> > 
> > We use it on our web and mail server to load ballance across
> multiple 
> > hosts. The way we have it configured
> > it will maintain a session for 15 minutes between a client and a 
> > specific server. So long as you have
> > qualify=yes in your configuration files, each client will continue
> to 
> > talk to the one server until they are turned off/
> > deactivated for at least 15 minutes (or whatever time period you 
> > configure into it). I've not tested LVS with
> > Asterisk, but it may be the right direction for you to take.
> > 
> > Cheers,
> > -Shaun
> > 
> > Matthew Boehm wrote:
> > 
> > >I've read several other emails and pages on the wiki but none give
> any
> > >deffinate answers. if you have 20 asterisk servers each with 4
> pri's, all
> > >running RealTime Extensions and RealTime SIPBuddies from the same
> MySQL
> > >server, what prevents you from putting all 20 servers behind a
> single load
> > >balancer? That way all of your UA's can use the same IP to
> register to; vs
> > >maintaining which customer is assigned to which machine.
> > >
> > >perhaps its just that i am not that familiar with load balancers.
> i was
> > >under the impression that a load balancer could/would send each
> recieved
> > >packet to a different server.
> > >this doesn't matter in the case of register requests since all
> asterisk
> > >boxes share same SIP registry database.
> > >
> > >but what about invite requests and the rtp stream? you would have
> a majorly
> > >broken conversation if each packet in the rtp stream went to a
> different
> > >asterisk box.
> > >
> > >or are load balancers SIP aware? or is there some sort of session
> control
> > >that the balancer is aware of and will send all packets in a "sip
> session"
> > >to the same asterisk box?
> > >
> > >and then what about meet me conferences? if 10 UA's all dial a
> conference
> > >DID number and all 10 get balanced to 10 different servers then
> they are all
> > >sitting in seperate rooms right?
> > >
> > >hints, opinions, facts...all welcome and appreciated.
> > >
> > >-Matthew
> 
> 
> 
> 
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=====
Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson at aero.org
  KG6OMK


		
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