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3.3.4 The IP Group

The Internet Protocol (IP) group, shown in Figure 3-5, is mandatory for all managed nodes and provides information on host and router use of the IP. This group includes a number of scalar objects that provide IP-related datagram statistics and the following three tables: an address table (ipAddrTable); an IP to physical address translation table (ipNetToMediaTable); and an IP forwarding table (ipForwardTable). Note that RFC 1354 defined the ipForwardTable, which replaces and obsoletes the ipRoutingTable in MIB-II. The IP subtree is designated {1.3.6.1.2.1.4}.


Figure 3-5.  The IP group

3.3.5 The ICMP Group

The Internet Control Message Protocol (ICMP) group, shown in Figure 3-6, is a mandatory component of IP and is defined in RFC 792. The ICMP group provides intranetwork control messages and represents various ICMP operations within the managed entity. The ICMP group contains 26 scalar objects that maintain statistics for various ICMP messages, such as the number of ICMP Echo Request messages received or ICMP Redirect messages sent. This group is designated {1.3.6.1.2.1.5} on the OID tree.


Figure 3-6.  The ICMP group

3.3.6 The TCP Group

The Transmission Control Protocol (TCP) group, shown in Figure 3-7, is mandatory and provides information regarding TCP operation and connections. This group contains 14 scalar objects and one table. The scalar objects record various TCP parameters and statistics, such as the number of TCP connections that the device supports, or the total number of TCP segments transmitted. The table, tcpConnTable, contains information concerning a particular TCP connection. The OID for this group is {1.3.6.1.2.1.6}.


Figure 3-7.  The TCP group

3.3.7 The UDP Group

The User Datagram Protocol (UDP) group, shown in Figure 3-8, is mandatory and provides information regarding UDP operation. Because UDP is connectionless, this group is much smaller than the connection-oriented TCP group. It does not have to compile information on connection attempts, establishment, reset, and so on. The UDP group contains four scalars and one table. The scalar objects maintain UDP-related datagram statistics, such as the number of datagrams sent from this entity. The table, udpTable, contains address and port information. The OID for this group is {1.3.6.1.2.1.7}.


Figure 3-8.  The UDP group

3.3.8 The EGP Group

The Exterior Gateway Protocol (EGP) group, shown in Figure 3-9, is mandatory for all systems that implement the EGP. The EGP communicates between autonomous (self-contained) systems, and RFC 904 describes it in detail. The EGP group includes 5 scalar objects and one table. The scalars maintain EGP-related message statistics. The table, egpNeighTable, contains EGP neighbor information. The OID for this group is {1.3.6.1.2.1.8}.


Figure 3-9.  The EGP group

3.3.9 The CMOT (OIM) Group

At one time, during the development of the Internet Network Management Framework, there was an effort to use SNMP as an interim step in the push for a network management standard, and to make the Common Management Information Protocol (CMIP) over TCP/IP (CMOT) the long-term, OSI-compliant solution. As a result, the CMOT group was placed within MIB-II. Experience has shown, however, that SNMP is not an interim solution, and that the OSI-related network management protocol requires unique MIBs. Therefore, it’s unlikely that you’ll encounter the OIM group within any commercially available SNMP managers or agents.

Nonetheless, the CMOT group was given a placeholder of {1.3.6.1.2.1.9 } in MIB-II (review Figure 3-1). RFC 1214 details that subtree, which specifies the OSI Internet Management (OIM) MIB [3-6]. At this time, RFC 1214 is classified as a “historic” protocol.

3.3.10 The Transmission Group

The Transmission group, shown in Figure 3-10 and designated {1.3.6.1.2.1.10}, contains objects that relate to the transmission of the data. RFC 1213 defines none of these objects explicitly. However, the document does say that these transmission objects will reside in the experimental subtree {1.3.6.1.3} until they are “proven.”


Figure 3-10.  The Transmission group

The “Assigned Numbers” document (currently RFC 1700 [3-7]) lists the following objects under the Transmission group:

  X25 – X.25 Packet layer objects
  IEEE802.3—CSMA/CD-like objects
  IEEE802.4—Token Bus-like objects
  dot5—Token Ring-like objects
  FDDI—FDDI objects
  LAPB—X.25 LAPB objects
  DS1—T1 carrier objects
  E1—E1 carrier objects
  PPP—Point-to-Point Protocol objects
  DS3/E3—DS3/E3 Interface objects
  SIP—SMDS interface objects
  FRAME-RELAY—Frame Relay objects
  RS-232—RS-232 objects
  Parallel—Parallel printer objects
  ARCNET—ARC network objects
  ARCNET-PLUS—ARC network plus objects
  ATM—ATM objects
  MIOX25 —Multiprotocol interconnect over X.25 objects
  SONET—SONET objects
  FRNETSERV—Frame Relay service MIB for DCE objects

RFC 1700 also lists other RFC references that provide details on these transmission types. By way of example, the sections below describe some of the transmission media MIBs that have been defined for broadband networks.


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