SNMP. Understanding SNMP. This chapter explains Simple Network Management Protocol (SNMP) as implemented by Cisco ME 2600X.

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1 This chapter explains Simple Network Management Protocol () as implemented by Cisco ME 26X. Understanding, page 1 Understanding Components, page 2 Understanding MIB, page 4 Understanding Traps, page 7 Understanding Community Names, page 9 Understanding Messages, page 9 Understanding This chapter explains Simple Network Management Protocol () as implemented by Cisco ME 26X. is an application layer communication protocol that allows network devices to exchange management information among these systems and with other devices outside the network. Through, network administrators can manage network performance, find and solve network problems, and plan network growth. makes network monitoring more cost effective and allows your network to be more reliable. Cisco ME 26X supports Version 2c (v2c). As compared to v1, v2c includes additional protocol operations and 64 bit performance monitoring support. OL

2 Understanding Components The figure below illustrates the basic layout idea of an -managed network. Figure 1: Basic Network Managed by The advantages of are as follows: is LAN based. is an open standard. can be easily extended. provides a common management platform for many different devices. Understanding Components An managed network consists of a manager, agents, and managed devices. The manager provides the interface between the human network manager and the management system. The agent provides the interface between the manager and the physical device being managed Management systems execute most of the management processes and provide the bulk of memory resources used for network management. A network might be managed by one or several management systems. 2 OL

3 Understanding Components The figure below illustrates the relationship between the network manager, the agent, and the managed devices. Figure 2: Example of the Primary Components An agent residing on each managed device translates local management information data such as performance information or event and error information caught in software traps, into a readable form for the management system. The figure below illustrates agent get requests that transport data to the network management software. Figure 3: Agent Gathering Data from a MIB and Sending Traps to the Manager The agent captures data from MIBs, which are device parameter and network data repositories, or from error or change traps. A managed element such as a router, access server, switch, bridge, hub, computer host, or network element is accessed through the agent. Managed devices collect and store management information, making it available through to other management systems having the same protocol compatibility. OL

4 Understanding MIB Note It is recommended that the Manager timeout value be set to 6 seconds. Under certain conditions, if this value is lower than the recommended time, the TNC/TSC card can be reset. However, the response time depends on various parameters such as object being queried, complexity, number of hops in the node and so on. Understanding MIB The Management Information Base (MIB) is a data structure that describes network elements as a list of data objects. The manager must compile the MIB file for each equipment type in the network to monitor devices. The manager and agent use a MIB and a relatively small set of commands to exchange information. The MIB is organized in a tree structure with individual variables being represented as leaves on the branches. A long numeric tag or object identifier (OID) is used to distinguish each variable uniquely in the MIB and in messages. The MIB associates each OID with a readable label and various other parameters related to the object. The MIB then serves as a data dictionary or codebook that is used to assemble and interpret messages. When the manager wants to know the value of an object, such as the state of an alarm point, the system name, or the element uptime, it will assemble a GET packet that includes the OID for each object of interest. The element receives the request and looks up each OID in its code book (MIB). If the OID is found (the object is managed by the element), a response packet is assembled and sent with the current value of the object included. If the OID is not found, a special error response is sent that identifies the unmanaged object. MIBs Supported in Cisco ME 26X The table below lists the MIBs supported in Cisco ME 26X. Table 1: MIBs Supported in Cisco ME 26X MIB Module ENTITY-MIB v2-mib Type Note The following objects do not return any value: snmptrap snmptraps sysortable sysorindex sysorid sysordescr sysoruptime 4 OL

5 MIBs Supported in Cisco ME 26X MIB Module CISCO-CDP-MIB CISCO-IETF-IP-FORWARD-MIB CISCO-IETF-IP-MIB IF-MIB RMON-MIB Type Note The following objects do not return any value: rmoneventsv2 etherstatstable historycontroltable etherhistorytable hosts hosttopn matrix filter capture logtable OL

6 MIBs Supported in Cisco ME 26X MIB Module IP-MIB TCP-MIB UDP-MIB RMON-MIB-V1SMI/HC-RMON-MIB Ether-Like-MIB CISCO-PROCESs-MIB OLD-CISCO-MEMORY CISCO-AAA-SERVER-MIB CISCO-AAA-SESSION-MIB CISCO-EVC-MIB CISCO-CLASS-BASED-QOS-MIB CISCO-IGMP-SNOOPING-MIB IEEE823-LAG-MIB Type Note The following objects do not return any value: ipsystemstatstable - ipsystemstatsipversion ipifstatstable - ifstatsrefreshrate ipaddressprefixtable - ipaddressprefixifindex ipaddresstable - ipaddressaddrtype ipifstatsifindex ipifstatsipversion ipaddressprefixtype ipaddressprefixprefix ipaddressprefixlength ipaddressaddr 6 OL

7 Understanding Traps The following generic MIBs are not supported in Cisco ME 26X: BRIDGE-MIB ENTITY-STATE-MIB CISCO-IETF-ISDN-CAPABILITY CISCO-OTN-IF-MIB Each MIB includes compliance and conformance groups these are not expected to return any output. ENTITY-MIB This is used for entity mapping. There is only one entity in ME26X and therefore no entity is mapped. As a result, this table does not respond with any data. IP-MIB ipnettomediatable, ipnettophysicaltable, ipdefaultroutertable, and ipv6 related tables are not supported. TCP-MIB tcplistenertable is not supported. The following feature MIBs are not supported in Cisco ME 26X: AAA IGMP CISCO-RADIUS-MIB CISCO-AAA-SERVER-EXT-MIB CISCO-RADIUS-EXT-MIB IGMP-MIB.my Note Access tables with table name are not supported. Understanding Traps IETF Traps Cisco ME 26X uses traps to generate all the alarms and events. The traps contain the following information: Object IDs that uniquely identify each event with information about the generating entity. Severity and service effect of the alarm (critical, major, minor, or event; service-affecting or non-service-affecting). Date and time stamp showing when the alarm occurred. Cisco ME 26X supports the generic IETF traps listed in the table below. OL

8 IETF Traps Table 2: Supported IETF Traps Trap coldstart warmstart Authentication linkdown linkup Description Agent up, cold start. Agent up, warm start. Community string does not match. Test linkdown trap. Test linkup trap. Examples of IETF Traps coldstart DISMAN-EVENT-MIB::sysUpTimeInstance = v2-mib::snmptrapoid. = v2-mib::coldstart CERENT-454-MIB::cerent454NodeTime. = D CERENT-454-MIB::cerent454AlarmState.1.1 = administrative -COMMUNITY-MIB::snmpTrapAddress. = " warmstart DISMAN-EVENT-MIB::sysUpTimeInstance = v2-mib::snmptrapoid. = v2-mib::warmstart CERENT-454-MIB::cerent454NodeTime. = D CERENT-454-MIB::cerent454AlarmState.1.1 = administrative -COMMUNITY-MIB::snmpTrapAddress. = " Authentication DISMAN-EVENT-MIB::sysUpTimeInstance = v2-mib::snmptrapoid. = v2-mib::authentication CERENT-454-MIB::cerent454NodeTime. = D CERENT-454-MIB::cerent454AlarmState.1.1 = administrative -COMMUNITY-MIB::snmpTrapAddress. = " linkup, linkdown Snmptrap sample for mgmt. i/f shut/noshut blr-ong-lnx1:168> snmptrapd -f -Lo -OQ -Ob -Ot -F "%V\n%B\n%N\n%w\n%q\n%P\n%v\n\n" :32:32 NET- version Started TRAP2, v2c, community public DISMAN-EVENT-MIB::sysUpTimeInstance = v2-mib::snmptrapoid. = v2-smi::enterprises v2-smi::enterprises = 1 v2-smi::enterprises = 2 v2-smi::enterprises = TRAP2, v2c, community public DISMAN-EVENT-MIB::sysUpTimeInstance = OL

9 Understanding Community Names v2-mib::snmptrapoid. = IF-MIB::linkDown IF-MIB::ifIndex = IF-MIB::ifAdminStatus = down IF-MIB::ifOperStatus = down IF-MIB::ifDescr = GigabitEthernet1/1 IF-MIB::ifType = ethernetcsmacd v2-smi::enterprises = "administratively down" TRAP2, v2c, community public DISMAN-EVENT-MIB::sysUpTimeInstance = v2-mib::snmptrapoid. = IF-MIB::linkUp IF-MIB::ifIndex = IF-MIB::ifAdminStatus = up IF-MIB::ifOperStatus = up IF-MIB::ifDescr = GigabitEthernet1/1 IF-MIB::ifType = ethernetcsmacd v2-smi::enterprises = "up" Understanding Community Names Community names are used to group trap destinations. Understanding Messages uses the following messages to communicate between the manager and the agent. Get GetNext GetResponse Set Trap The Get and GetNext messages allow the manager to request information for a specific variable. The agent, upon receiving a Get or GetNext message, will issue a GetResponse message to the manager with either the information requested or an error indication as to why the request cannot be processed. A Set message allows the manager to request a change be made to the value of a specific variable in the case of an alarm remote that will operate a relay. The agent will then respond with a GetResponse message indicating the change has been made or an error indication as to why the change cannot be made. The Trap message allows the agent to inform the manager of an important event. An Trap is a change of state (COS) message it could mean an alarm, a clear or simply a status message. OL

10 Understanding Messages 1 OL