[asterisk-dev] load balancing / failover support ideas

[Vadim Lebedev]

Stephen Coles wrote:
>
> I need to add multiple internet lines to my asterisk setup [as my 
> internet connects are slow (DSL distance problem) and I don't want to 
> pay for a lease line] with load balancing between the lines - googling 
> and there's no easy/cheap way to do this.  Redundancy\failover seems 
> just as hard.  So I had some ideas and just wanted to share them, 
> maybe some people will like them and there get work upon and find 
> their way into asterisk, just be binned or maybe asterisk can do this 
> already [if it can sorry].  But here goes:
>
>  
>
> To the iax2.conf I would add:
>
>  
>
>                 priority                                 (what order 
> to use the context in)
>
>                 calls_out                                              
> (number of call going out allow on this context - before the next 
> group context is used)
>
>                 calls_total                                            
> (total number of calls in and out allow on this context - before the 
> next group context is used)
>
>                 loadbalance                                        
> (true or false - do i distribute the calls evenly between the group)
>
>                 
> gateway                                                               
> (what IP address to send the calls out on)
>
>                 externip                                               
> (needed if behind a NAT)
>
>                 
> localnet                                                (needed if 
> behind a NAT)
>
>                
>
> then you could dial using:
>
>                 Dial(IAX2/GROUP:{first part of context to match}/22122)
>
>                
>
> e.g.:
>
>                 [outbound - voip minutes]
>
>                 priority = 1
>
>                 loadbalance = yes
>
>                 gateway = 192.168.16.5
>
>  
>
>                 [outbound - telstar]
>
>                 priority = 2
>
>                 loadbalance = yes
>
>                 gateway = 192.168.16.6
>
>                
>
>                 [outbound - voip hip]
>
>                 priority = 3
>
>                 loadbalance = yes
>
>                 gateway = 192.168.16.7
>
>                
>
> then dial using:
>
>                 Dial(IAX2/GROUP:outbound/22122)
>
>                
>
> chan_iax2 would work out that I wanted to use a group and use any 
> context that started outbound so any of the 3 contexts above would be 
> valid routes.  The routes would be ordered by priority, so chan_iax2 
> would use voip minutes first, telstar second and voip hip third.  
> Because I'm using the loadbalance option it will spread the traffic 
> evenly across the 3 connections.  So if voip minutes current has 2 
> calls on, telstar has 1 call on and voip hip has 5 calls on.  A new 
> call would go out on telstar as this has the least amount of calls.
>
>  
>
>  
>
> this could be expanded upon to do failover by adding a checkroute to 
> each context above asterisk can every X minutes check that the route 
> is still valid and if it isn't mark it so it isn't used.
>
> If a call was current in progress and the connection went down, if all 
> 3 contexts were using the same TISP you could reroute the call (using 
> the unique channel id) over another outbound context to the same TISP 
> match up the unique call id and the call wouldn't be dropped - this 
> would be easy to do for the IAX  than the SIP protocol because its 
> owned by asterisk.  The problem with doing this for the sip protocol 
> is that it's a standard and would require a RFC (Request for Comments).
>
>  
>
> To make this easier to develop you could you could add it to IAX3 - so 
> you could ship asterisk and allow the user to use IAX2 or the new 
> EXPERIMENTAL IAX3 (like you do with the new faster dial plan pattern 
> matching routine that you need to turn on in extension.conf)
>
>  
>
> Stephen Coles
>  IT Services
>  Wellpak(UK) Ltd
>


Stephen, 

I think i would approach this problem by defining new channel technology,
This way  the load balancer will be able to operate on ANY underlying tech.


Thanks
Vadim
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