[sr-dev] [Kamailio 1.5 LCR] gw with same IP but different port is not loaded

[Juha Heinanen]

Iñaki Baz Castillo writes:

> > the comment is that currently uniqueness of gws is based only on gw's ip
> > address or hostname , i.e., port is not considered.  after quick
> > look at
> > the code, it should be quite easy to add checking of port too.
> 
> SInce different gws can exist in gw table with same ip:[port] but
> different attributes (strip, flags, etc) I think it should be possible
> to load gateways with same ip[:port] for same request if theses
> gateways match the rules.

yes, i agree that it should be possible to load two gws with the same ip
or hostname if port is not given or if it is given and is different in
the two.

> Main reason: current design makes *very* difficult to manage the
> tables content via an admin interface (i.e. a web interface).
> Also, if I want to include same gateway (so same IP, port and
> attributes) in two rules then I must to repeat same data in two
> different gw entries. This is not good from a design point of view.

ok.

> What I'll propose is:
> 
> - table 'lcr_rules' (same as 'lcr') includes entries with
> 'instance_id', 'grp_id' and so. Also it would contain two new columns:
> 'enabled' (the rule is just loaded if it's 1), and 'stop' (no new
> rules are inspected when 'load_gws()' finds this rule). More about
> this at the end of the mail.
> Also I would add a new schema constain: a composite UNIQUE key for
> columns 'prefix', 'grp_id' and 'priority' as it makes no sense two
> rules with same prefix, grp_id and priority (which is chosen first? is
> it random?).
> - table 'lcr_gws' include gateways definition. Same as current 'gw'
> table but *without* 'grp_id' and 'instance_id' columns.
> 
> - table 'lcr_groups' contains these columns:
>   - id:  primary key as usual.
>   - grp_id: The group identifier.
>   - gw_id:  integer pointing to the id column of an entry under
> 'lcr_gws' table.º
> If a group contains 2 gateways then two entries would exist in this
> table with same 'grp_id', each one with 'gw_id' pointing to the
> corresponding entry under 'lcr_gws' table.

sounds ok.

> Because it's ugly to do so in the script, it makes unfeasible to admin
> it via a web interface. A common use case:
> - I want a default route using gw1 and gw2 (for any prefix).
> - In calls to 001 (USA) I want to use *just* gw3, so I could create a
> lcr rule with prefix 001 and grp_id=X, and a lcr_group with id=X
> containing just gw3.
> - If gw3 is down or replies 503 (this is, if the USA lcr rule fails) I
> don't want to try the default route (gw1 and gw2). This is not
> possible with the current design as the default route (lcr rules with
> no prefix) would be loaded automatically.
> - With my proposal (a column "stop" with value 1) there is no need to
> coding ugly and static code in failure_route. Instead load_gws() would
> stop inspecting lcr_rules table when a rule with "stop=1" is found.

does this cover the case where there are two equal priority gw groups
defined for prefix 001?

> I suggest/propose all of this due to my real experience. I've deployed
> a proxy for load balancing, failover and routing (based on prefix) to
> some PSTN gateways and after implementing it I really miss the above
> features.

thanks for your suggestions, it just remains to implement them :-).

-- juha