snmprealwalk indexes the values using the oid instead of an integer. This is useful when you need data that is contained in the oid as well as the value.
Here's an example for retrieving and printing vlan info:
//
// I have collected the vlan identifiers earlier from the 3com mib and they are stored in the $vlan table.
//
for($n=0;$n<count($vlan);$n++){
print $vlan[$n][id]." ".$vlan[$n][name]."<br>\n";
$ifStackStatusTable=@snmprealwalk($switch, $community, ".1.3.6.1.2.1.31.1.2.1.3.".$vlan[$n][id]); // ifMIB.ifMIBObjects.ifStackTable.ifStackEntry.ifStackStatus
for(reset($ifStackStatusTable); $port = key($ifStackStatusTable); next($ifStackStatusTable)){
print "$port=$ifStackStatusTable[$port]<br>";
}