A starting point might be something like this:

#!/usr/bin/perl
use strict;
use Sort::Key::IPv4 qw(ipv4sort);
open(TEXT,"dump.txt")or die("Text not found");
my %packets;

while (<TEXT>) {
  if ( /IP\s+(\d+\.\d+\.\d+\.\d+)(\.(\d+))?\s+>\s+(\d+\.\d+\.\d+\.\d++
+)(\.(\d+))?\:\s+(\w+)/ ) {
    my ($srcip, $srcport, $dstip, $dstport, $proto) = ($1, $3, $4, $6,
+ $7);
    printf "%16s [%5d] --> %16s [%5d] (%s)\n", $srcip, $srcport, $dsti
+p, $dstport, lc($proto);
    if ($srcport == $dstport) {
      # one IP to another on the same port...
      $packets{$srcport}{$srcip}{$dstip}++
    }
  }
}
foreach my $port (sort { $a <=> $b } keys %packets) {
  # ports sorted ascending
  foreach my $srcip ( ipv4sort keys %{$packets{$port}}) {
    # source IPs sorted ascending
    foreach my $dstip ( ipv4sort keys %{$packets{$port}{$srcip}}) {
      # dest IPs sorted ascending
        print "On port $port, from $srcip to $dstip, there were $packe
+ts{$port}{$srcip}{$dstip} packets\n";
      }
    }
  }
}
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Also, you should read about the (?:pattern) in perlre - there's no need to capture in your regex anything you don't want.