#...
my @lines = ();
open my $inFile, '<', 'svrrp.txt' or die "Couldn't open svrrp.txt: $!";
my $currIface = "";
while (<$inFile>) {
  chomp;
  if (my $iface = ($_ =~ /^Interface\s(\w+)$/) {
    processlines($currIface, @lines);
    $currIface = $iface;
    @lines = ();
  }
  push @lines, $_;
}
processlines($currIface, $lines); # to process last interface block
#...

sub processlines() {
  my $iface = shift;
  return unless $iface;
  # declare any vars
  foreach (@_) {
    # do your pattern matching here
  }
  # print your findings
}