he TCP/IP stack the protocols can be chosen to 16.4. A total of about 120 objects can be held in MIB I, which has match the application. Examples are HDLC for point-to-point net- been updated to MIB II (RFC 1158) with a capacity of about 200 works, Ethernet for local area networks and X.25 for wide area objects. This will mean that more vendor specific data can be networks. accommodated, increasing the ability of the system to control a mix Comparing with the OSI system of Figure 16.11 it is evident that of networks. Vendor specific objects are referred to as extended the TCP/IP stack is relatively simple. OSI has a width of standards, variables. They are put in the public domain SO that anyone can with a choice of connectionless or connection oriented operation. It design a manager to control them. also covers a wider range of network technologies. Items can The SMI defines a registration sub-tree structure for the MIB, as therefore be chosen at the various levels, in order to obtain optimum shown in Figure 16.23. Three branches come from the root, branch communication efficiency for any application. 1 administered by ISO, branch 2 by CCITT and branch 3 jointly by ISO and CCITT. Under the ISO branch are other sub-branches, 16.9.2 Management of TCP/IP networks number 3 being assigned by ISO to 'other standards organisations' (org). The US Department of Defence has been assigned sub-branch Work on managing the large base of TCP/IP networks started in 6 (dod) under org. The DOD then assigned its first sub-branch (1) 1987, the emphasis at that time being on developing a manager for to Internet. the routers (gateways) used to interconnect the widely spaced net- Under Internet there are four sub-branches. Management (mgmt) works. The first demonstration of such a system, called the Simple holds all the standard MIBs and the private sub-branch holds vendor Gateway Monitoring Protocol (SGMP), was conducted in August specific MIBs. The experimental sub-branch holds MIBs which will 1987. eventually become standard but are