Description: This object defines the values to be placed in the TypeOfService
   octet of each IP packet sent out or forwarded by the VR. The valid 
   range covers both 7-bit configurations recommended in RFC 1349 
   (Precedence and TOS bits) and 6-bit configurations recommended 
   in RFC 2474 (Differentiated Services). If the value selected 
   is 256, the DsByte is not changed and packets are forwarded with 
   their existing TypeOfService byte value.

   This object can be an IPv4 TOS octet:
   0     1     2     3     4     5     6     7
+-----+-----+-----+-----+-----+-----+-----+-----+
|                 |                       |     |
|   PRECEDENCE    |          TOS          | MBZ |
|                 |                       |     |
+-----+-----+-----+-----+-----+-----+-----+-----+

   Precedence (from RFC 791)

   111 - Network Control
   110 - Internetwork Control
   101 - CRITIC/ECP
   100 - Flash Override
   011 - Flash
   010 - Immediate
   001 - Priority
   000 - Routine

   TOS (from RFC 1349)

   1000   --   minimize delay
   0100   --   maximize throughput
   0010   --   maximize reliability
   0001   --   minimize monetary cost
   0000   --   normal service

   MBZ (must be zero) is unused.


   Or this object can be a DS field (from RFC 2474):
   0     1     2     3     4     5     6     7
+-----+-----+-----+-----+-----+-----+-----+-----+
|                                   |           |
|               DSCP                |     CU    |
|                                   |           |
+-----+-----+-----+-----+-----+-----+-----+-----+

   DSCP: differentiated services codepoint
   CU:   currently unused

   DSCP is used to select the PHB (per-hop behavior) a
   packet experiences at each node. It is recommended that
   bits 0-2 of the DSCP field be employed in a manner 
   similar to, or subsuming, the deployed uses of the 
   IP Precedence field of an IPv4 TOS octet to maintain 
   some form of backward compatibility.