Figure 1

                            .
                            |
              --------------------------------------------------
              |             |               |                  |
           ccitt(0)       iso(1)          itu(2)       joint-iso-ccitt(3)
                            |
                   ---------------------
                   |     |      |      |
                                     org(3)
                                       |
                                     dod(6)
                                       |
                                   internet(1)
                                       |
                                     mgmt(2)
                                       |
                                    mib-2(1)
                                       |
       ----------------------------------------------------------------
       |         |               |           |     |      |     |     |
    system   interfaces   addr-translation   ip   icmp   tcp   udp   egp
      (1)       (2)             (3)         (4)   (5)    (6)   (7)   (8)