I'm not sure you are hitting the correct OID.
I think what you want to do is snmpwalk.
snmp trap is something the device sends you.

<snip sorry>
In my environment the access layer devices are just layer 2 devices.
So I can't get from ip -> port number.

I keep a history of ip -> mac addresses

I run an old tool called arpwatch.
ftp://ftp.ee.lbl.gov/arpwatch.tar.gz

It it builds three files:
first.txt ## this keeps track when it first saw a mac address.
current.txt ##this shows the ip/mac it saw on the last run
history.txt ##this show the hist of a mac address over time.

head history.txt
20091210/08:27 10.3.2.4 00:04:4E:60:C0:54
20111025/00:30 10.3.2.3 00:0F:CB:A1:80:ED
20100913/16:30 10.3.2.3 00:0F:CB:A1:80:ED
20110623/12:30 10.3.2.5 00:14:22:F3:EC:45
20091210/08:27 10.3.2.3 00:14:7C:4B:0C:00
>>>snip...

I then have to harvest cam tables from the switches and map to this data.

I need the port they are on really fast. (rouge DHCP, dup address, etc)

#!/usr/bin/perl -w
use strict;

## sweep.pl
## program havest ethernet cam tables from a list switches contained
## in files in $switch_file_dir 
## rev 1.1
## 1.1 changes the ouput file, and fixes it to append, adds grep examp
+le
## this line left blank

####
# modules
use Parallel::ForkManager;

###
# global varibles
my $rev = "1.1";
my $count=0;
my $debug = 1;
my $answer = "n";
my $switch_num_input ="";
my @switchfiles_array = ();
my $directory = "Data"; # directory for output 
my $max =50;    # number of concurrent processes
my %port_count_hash;
my @bridgetable;


## switchfile is just a list of switches
## each building has a file in the dir Switchfiles/
## building14 building 15...
# witch the snmp read string

## switchfile example
## 192.168.1.10 public 
## 192.168.1.15 public 


#get the list of switchfiles
while ($answer =~ /^n/i ) {
    $count=0;
    @switchfiles_array =<Switchfiles/*>;
    &draw_line;
    &print_switchfiles (@switchfiles_array);
    &draw_line;
    print "(ver$rev)";    
    print "\t enter number?: ";
    chomp($switch_num_input = <STDIN>);
    print "\n\n";
    die "please enter a number\n\n\n" unless $switch_num_input =~/\d+$
+/;
    die "number doesn't exist\n\n\n" unless $switchfiles_array[$switch
+_num_input];    
    my $file_check = &remove_dir($switchfiles_array[$switch_num_input]
+);
    print "\t\t-----> $file_check\n\n\n";
    print "(y/n) ?: ";
    $answer = <STDIN>;
}

mkdir $directory, 0700 unless (-d "$directory");
&erase_directory ($directory);
unlink "ether.txt";

my $switch_file = <$switchfiles_array[$switch_num_input]>;
open FH , $switch_file;
my @switch_file_lines = <FH>;
close FH;
print"";
my $pm = new Parallel::ForkManager($max);

$pm->run_on_finish(
    sub { my ($pid, $exit_code, $ident) = @_;
    }
);

$pm->run_on_wait(
    sub {
     print "please hold....\n";   
    }    
);

foreach my $child(0..$#switch_file_lines) {
    my $pid=$pm->start($switch_file_lines[$child]) and next;  #this co
+de is the child process
    my $switches_line = $switch_file_lines[$child];
    my @lines_array = split /\s+/, $switches_line;
    my $ip = $lines_array[0];
    my $community = $lines_array[1];

    my @bridgetable = `snmpwalk -Cc -c $community -v 1 $ip .1.3.6.1.2.
+1.17.4.3.1.2`;  

    # number of macs on each port   
    foreach (@bridgetable) {
        chomp;
        my @bt_array = split /[\. ]/,$_;
        $port_count_hash{$bt_array[14]}++;
    } 

    open(SWEEP_OUT,">>$directory/$ip");

    foreach (@bridgetable) {
        my @bt_array = split /[\. ]/,$_;
        my $port_number = $bt_array[14];
        printf SWEEP_OUT "%02x%02x%02x%02x%02x%02x",$bt_array[6],$bt_a
+rray[7],$bt_array[8],$bt_array[9],$bt_array[10],$bt_array[11];
        print SWEEP_OUT " $ip/$port_number" , " $port_count_hash{$port
+_number} \n";
    }
$pm->finish($child)
}

print "child leaving pool\n";
$pm->wait_all_children;
print "all child proccesses done.\n";

my @files = <$directory/*>;
open SWEEP_OUT, ">>ether.txt";

foreach (@files){
    open SWITCH_FH,"<$_";
    my @all_lines = <SWITCH_FH>; 
        foreach (@all_lines) {
            print SWEEP_OUT $_;
        }

}

&draw_line;

print " \t You can search the file \"ether.txt\" with the command \"gr
+ep\" \n";
print " \t Ethernet addresses are formatted like c42c032225a9\n";
print " \t example: grep 2225a9 ether.txt";

&draw_line;

########################
# subs

sub remove_dir {
    $_ = shift @_;
    $_=~/^\S*\/(.*)/; # set after dir to $1
    $_=$1; # remove leading dir without looking anything up :)        
+ 
}

sub draw_line {
    print "\n";
    print "=" x60;
    print "\n";
}

sub print_switchfiles {
    my @switchfiles_array = @_;
    foreach (@switchfiles_array) {
    $_ = &remove_dir ($_);
    print"$count.  $_\n";
    $count++;    
    }    
}

sub erase_directory {
    my $directory = shift @_;
    my @files = <$directory/*>;
    foreach (@files){
        unlink "$_";
    }
}
[download]

This is all based on the standard mib tree so depending on what you were after, this could work for you too.

Good luck, Rob