[Serusers] About a SIP load balancing document involving SER

[Jiri Kuthan]

we mean a load-balancer (Which is roughly a crippled proxy), which has 
the same IP address as the regular proxy servers behind it.

-jiri

Iñaki Baz Castillo wrote:
> El Martes, 14 de Octubre de 2008, Martin Hoffmann escribió:
>> Iñaki Baz Castillo wrote:
>>> 2008/10/13 Jiri Kuthan <jiri at iptel.org>:
>>>> The thing here is that actually a load-balancer vendor is free to build
>>>> stuff his way -- he is not compelled to build a proxy or B2BUA and go
>>>> to some certification authority, he is supposed to build something that
>>>> load-balances well. I'm intimately aware of some load-balancers that
>>>> are close to being a kind of "transparent proxy", which is just fine:
>>>> it doesn't put itself in signaling and it handles routing by state
>>>> table.
>>> Well, but what I mean is that the vendor needs, not just a custom LB
>>> which doesn't add "Via" header, but also devices behind the LB (other
>>> proxies or gateways) being not SIP compliant in points 18.2.1 & 18.2.2
>>> of RFC3261.
>> We do have garden variety proxies behind our load balancers and they are
>> not aware of the presence of those load balancers. The trick is to give
>> them all the same IP and have the balancers work one layer below. From
>> the IP perspective, they are all one. Or something.
> 
> Thanks for your comment. Please let me understand what you mean:
> 
>   " the trick is to give them all the same IP and have the balancers work one
>     layer below"
> 
> Do you mean having various LB proxies all of them with same IP? If it, them 
> all the proxies behind the LB's will always see the same source IP, and will 
> reply to that IP, so the responses will arrive, at least, to one LB, am I 
> wrong?
> Anyway, I don't understand the purpose and advantages of this method. If I 
> understood correctly, it could occur the following:
> 
> ---------------------------------------------------------------------
>   proxy1   proxy2   proxy3    proxy4   proxy5
> 
>                    LB1         LB2         LB3 
> 
>                                 UA
> ---------------------------------------------------------------------
> (all LB's have the same IP (1.1.1.1) in their interface with the proxies 
> behind).
> 
> - UA sends an INVITE to LB1.
> - LB1 forwards the INVITE to proxy1.
> - proxy1 sees 1.1.1.1 as source IP so add "received=1.1.1.1" to top Via (the 
> top Via can be Via added by LB1 or the Via added by UA if LB's don't add 
> Via).
> - proxy1 replies to 1.1.1.1.
> - Since that IP is shared by all the LB's the response arrives to LB3.
> 
> I suppose I didn't understant well since I see no benefict in this scenario.
> 
> 
> Thanks a lot for your comment.
> 
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