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Unformatted text preview: 00:20:0f:2d:38 18.104.22.168 1 0x00:80:ad:03:6a:80 22.214.171.124 2 0x00:02:16:48 126.96.36.199 2 0x00:02:3c:48 188.8.131.52 atIflndex Figure 25.20 Example of at table (ARP cache).
The AppleTalk physical addresses on interface number 2 are 32-bit values, not the 48-bit Ethernet
addresses to which we're accustomed. Also note that an entry exists for our router (netb at
184.108.40.206), which we expect, since kinetics and netb are on the same Ethernet
(140.252.1) and kinetics must use ARP to send the SNMP responses back to us.
The ip group defines numerous variables and three tables. Figure 25.21 defines the simple
Name Datatype R/W
1 means the system is forwarding IP datagrams, and
2 means it is not. ipForwarding [1..2] ipDefaultTTL INTEGER * Default TTL value when transport layer doesn't
provide one. ipInReceives Counter Total number of received IP datagrams from all
interfaces. ipInHdrErrors Counter Number of IP datagrams discarded because of
header errors (e.g., checksum error, version number
mismatch, TTL exceeded, etc.). ipInAddrErrors Counter Number of IP datagrams discarded because of
incorrect destination address. ipForwDatagrams Counter Number of IP datagrams for which an attempt was
made to forward. ipInUnknownProtos Counter Number of locally addressed IP datagrams with an
invalid protocol field. ipInDiscards Counter Number of received IP datagrams discarded because
of a lack of buffer space. ipInDelivers Counter Number of IP datagrams delivered to appropriate
protocol module. file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/snmp_sim.htm (18 of 33) [12/09/2001 14.47.40] Chapter 25. SNMP: Simple Network Management Protocol ipOutRequests Counter Total number of IP datagrams passed to IP for
transmission. Does not include those counted in
ipForwDatagrams. ipOutDiscards Counter Number of output IP datagrams discarded because
of a lack of buffer space. ipOutNoRoutes Counter Number of IP datagrams discarded becaus...
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- Spring '12