One possibility is to encapsulate at the DBI level, say using DBIx::AnyDBD.

package NetworkClass;

use base qw(Class::DBI);

use DBIx::AnyDBD;
our $dbh;

sub Db_Main {    
    $dbh ||= DBIx::AnyDBD->connect("dbi:Oracle:network", 
        "user", "pass", {}, "NetWorkDBD");
}
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Under the hood you class NetWorkDBD does the serious work; managing your farm of real DB connections.

Simple sql queries are translated into a series of actual SQL queries. Results are aggregated and returned.

package NetWorkDBD;

use SQL::Parser;

sub new {
    my ($dsn, $user, $pass, $atts,$pkg) = @_;


#    ...

}

sub selectrow {
    my $self = shift;
    my $sql = shift;
    my @params = @_;
# ...
}
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You then have the option of direct use of the DBI handle and/or adding a Class::DBI layer.