One more question
I want to expand this Service with DELETE request
In this case my output2.csv should have this look:

output2.csv (id,name,description,ip) - Secondary System

01,TEST_1,,10.56.7.80
02,TEST_2,bla,10.57.80.9
03,TEST_3,,10.60.251.9
[download]

TEST_1,10.56.7.80
TEST_6,10.66.251.9
TEST_5,10.66.81.9
[download]

I should check, if there is device in Secondary System, that absent in Primary System with out description.
In my case thist is TEST_3
I should delete such devices
I've tried to do it with the previous example, but I do not know perl really good.....

#!/usr/bin/perl
 use strict;
 use warnings;
 use LWP::UserAgent;
 use XML::Twig;
 use autodie;
 use Data::Dumper;

my @filename = ('output1.csv', 'output2.csv');

my %file1 = () ;
open my $fh, '<', $filename[0]; # using autodie
while (<$fh>){
  chomp;
  my ($name,$ip) = split /\s*,\s*/;
  $file1{$name} = $ip;
}
close $fh;

my %file2 = () ;
my %ip2name = ();

open $fh, '<', $filename[1]; # using autodie
while (<$fh>){
  chomp;
  my ($id,$name,$description,$ip) = split /\s*,\s*/;
  $file2{$name} = [$id,$ip];
 # $ip2name{$ip} = [$id,$name];
 }
close $fh;


# determine updates and additions requires
my @delete  =();

foreach my $name (sort keys %file2) {
  my $ip1 = $file2{$name};
  if ( not exists $file1{$name} ){
    # check if ip exists
   if ( $description=null ){
    my $id = $ip2name{$ip1};
    
       print "DELETE name : '$name'\n";
       push @delete,[$id,$name,$description,$ip]
   }
  }
}

my $ua = LWP::UserAgent->new(
   ssl_opts=> {
#    SSL_verify_mode => SSL_VERIFY_NONE,
    verify_hostname => 0,}
);


  for (@delete){
  my ($id,$name,$description,$ip1) = @$_;

  my $uri="https://hostname:9060/ers/config/networkdevice/$id";
  my $req = HTTP::Request->new('DELETE', $uri,
     [Accept=>'application/vnd.com.cisco.ise.network.networkdevice.1.1
++xml',
     Content_Type=>'application/vnd.com.cisco.ise.network.networkdevic
+e.1.1+xml; charset=utf-8']);

  $req->authorization_basic("user", "user");

  print $req->as_string; # testing

  my $res = $ua->request($req);
  if ($res->is_success) {
    print $res->status_line, "\n";
  } else {
    print $res->status_line, "\n";
    }
  }
}
[download]

There is no Problem this the Server, when I'm doing multiply DELETE separately
I think my promlem is here:

foreach my $name (sort keys %file2) {
  my $ip1 = $file2{$name};
  if ( not exists $file1{$name} ){
    # check if ip exists
   if ($description=null){
    my $id = $ip2name{$ip1};
       print "DELETE name : '$name'\n";
       push @delete,[$id,$name,$description,$ip]
    }
  }
[download]