TCP IP Illustrated

Both are described briefly in rose 1994 simple

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Unformatted text preview: ing of the object identifiers, not the human-readable names. 2. The ordering of the rows in a table depends on the values of the indexes for the table. In Figure 25.13, 67 is lexicographically less than 161, which is lexicographically less than 520. Figure 25.14 shows this column-row order for our sample UDP listener table. file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/snmp_sim.htm (10 of 33) [12/09/2001 14.47.40] Chapter 25. SNMP: Simple Network Management Protocol Figure 25.14 UDP listener table, showing column-row ordering. We'll also see this column-row ordering when we use the get-next operator in the next section. 25.7 Simple Examples In this section we'll show some examples that fetch the values of variables from an SNMP agent. The software used to query the agent is called snmpi and is from the ISODE system. Both are described briefly in [Rose 1994]. Simple Variables We'll query a router for two simple variables from the UDP group: sun % snmpi -a gateway -c secret snmpi> get udpInDatagrams.0 udpNoPorta.0 udplnDatagrams.0=616168 udpNoPorts.0=33 snmpi> quit The -a option identifies the agent we want to communicate with, and the -c option specifies the SNMP community. It is a password supplied by the client (snmpi in this case) and if the server (the agent in the system gateway) recognizes the community name, it honors the manager's request. An agent could allow clients within one community read-only access to its variables, and clients in another community read-write access. The program outputs its snmpi> prompt, and we can type commands such as get, which translates into an SNMP get-request message. When we're done, we type quit. (In all further examples we'll remove this final quit command.) Figure 25.15 shows the two lines of tcpdump output for this example. 1 0.0 2 0.348875 (0.3489) sun.1024 > gateway.161: GetRequest(42) gateway.161 > sun.1024: GetResponse(46) Figure 25.15 tcpdump output for simple SNMP query. The request for the two varia...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.

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