14 Oct
2008
14 Oct
'08
6:52 p.m.
2008/10/13 Jiri Kuthan <jiri(a)iptel.org>rg>:
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.
This is, it's not enough if the vendor customizes the LB, it also
needs to modify the SIP devices after the LB. If not, the
proxies/gateways behind the LB will always reply to the source IP (the
IP of LB) regardless of the content/existance of a Via added (or not)
by LB.
An example: if a vendor just controls the LB and use gateways of
different carriers, the LB will always receive the responses to the
initial INVITE transaction (except if the gateways are not SIP
compliant when sending a response).
I think this is very clear in points 18.2.1 and 18.2.2, am I wrong?
Thanks a lot for your comments.
--
Iñaki Baz Castillo
<ibc(a)aliax.net>