use strict;
use warnings;

my $string = <<HERE;
MAC Address: xx:aa:aa:aa:aa:aa
  IP addr: a.b.c.d
           x.y.z.f
  Name:  xxxx
  Neighbors attached: 1
    Additional: xxx Interface: xxx Index: xxx
       Link Cost: xx 
       Link Speed: xx Mbps
MAC Address: xx:aa:aa:aa:aa:aa
  IP addr: a.b.c.d
           x.y.z.f
  Name:  xxxx
  Neighbors attached: 1
    Additional: xxx Interface: xxx Index: xxx
       Link Cost: xx 
       Link Speed: xx Mbps
HERE

while( 
    $string =~ m/
        MAC\sAddress:\s(?<mac>\S+)\s+
        IP\saddr:\s(?<ip1>\S+)\s+(?<ip2>\S+)
        .+?
        Link\sCost:\s(?<cost>\S+)\s+
        Link\sSpeed:\s(?<speed>\S+)\sMbps
    /sxg
) {
    print "Node with MAC address: $+{mac} has IP = $+{ip1}, $+{ip2} " .
          "and Link Speed = $+{speed} and Link Cost = $+{cost}\n";
}