[Serusers] use of SRV records for failover

[sip]

Markus,

I'm not sure I fully understand.  Are you trying to essentially load
balance by using SRV records in DNS?

Those two aren't really the same thing. You'd need some sort of gateway
software/hardware that keeps track of current state of the sub server
processes in order to determine at any given point which is up and which
is down... PLUS it sounds like you want to make it so that each is
assigned a weight.

SER doesn't really have the ability to do that on its own. You could
probably MAKE it do that with some very creative scripting and/or
database queries... but it wouldn't be pretty.

It would be easier to use an actual load balancer/load balancing
software to accept initial connections and forward those accordingly.

For instance, if you want SER1 to forward calls to EITHER SER2 or SER3,
then you would have SER1 point to a load-balanced virtual server. Some
other software would handle the load balancing and SER would be unaware
that it wasn't pointing to a normal server. This could be done pretty
easily using linux virtual server or some such and it wouldn't require
any special setup in SER.

N.

On Tue, 27 Sep 2005 10:31:43 +0200, Markus Storm wrote
> Dear all,
> 
> we would like to do loadbalancing and failover with SRV in our multi-
> SER setup.
> 
> I.e. ser-1 gets a call and can forward the call to either ser-2 or 
> ser-3. There's a DNS SRV record that points to both, ser-2 and ser-3 
> (same weight, same priority). On ser-1, I use the SRV name to 
> forward calls to.
> 
> Now I'd like ser-1 to distribute calls according to weight and 
> priority, i.e. 50% to ser-2 and 50% to ser-3. But it doesn't, it 
> keeps sending to ser-2 (the first entry in the SRV record's list).
> 
> Also, if say ser-2 goes down, I'd like ser-1 to notice that and only 
> ever try to send subsequent requests to ser-2 until <something> 
> happens (e.g. until the SRV record TTL expires).
> 
> I found a one-year old message in the archives stating that neither 
> of this is possible
> (unless I use a DNS A record that points to multiple IP addresses, 
> but that's not what I want).
> 
> Is it meanwhile possible with the current SER software ?
> 
> thanks
> Markus
> 
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