[Serusers] About a SIP load balancing document involving SER

[Iñaki Baz Castillo]

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.











-- 
Iñaki Baz Castillo