Remote Network Monitoring (RMON) Mi-Jung Choi Dept. of Computer Science KNU Email: mjchoi@kangwon.ac.kr 1 1

Table of Contents Basic Concepts RMON Goals RMON MIB Table Management RMON MIB Groups RMON2 3

RMON Basic Concepts Extends the SNMP functionality without changing the protocol Allows the monitoring of remote networks (internetwork management) MAC-layer (layer 2 in OSI) monitoring Defines a Remote MONitoring (RMON) MIB that supplements MIB-II with MIB-II, the manager can obtain information on individual devices only with RMON MIB, the manager can obtain information on the LAN as a whole called network monitors, analyzers or probes 4

RMON RFCs 4

RMON Goals Monitoring subnetwork-wide behavior Reducing the burden on agents and managers Continuous off-line monitoring in the presence of failures (in network or manager) Proactive monitoring perform some of the manager functions (e.g., diagnostics) Problem detection and reporting Provide value-added (analyzed) data Support multiple managers 4

Example Configuration for Remote Monitoring Management console with RMON probe Ethernet Central Site Router Router Local management console with RMON probe Router Router Ethernet PC with RMON probe FDDI backbone Bridge Router with RMON probe Ethernet Token Ring LAN PC with RMON probe 4

Example of RMON probe with two interfaces agent a b RMON probe c e d Interface 1 Interface 2 Subnetwork X Y 4

Control of Remote Monitors RMON MIB contains features that support extensive control from NMS Configuration control Action Invocation RMON MIB is organized into a number of functional groups Each group may contain one or more control tables and one or more data tables Control table (typically read-write) contains parameters that describe the data in a data table (typically read-only) 4

Configuration Control At configuration time, NMS sets the appropriate control parameters to configure the remote monitor to collect the desired data the parameters are set by adding a new row to the control table or by modifying an existing row a control table may contain objects that specify the source of data to be collected, the type of data, the collection timing, etc. To modify or disable a particular data collection function: it is necessary first to invalidate the control row this causes the deletion of that row and the deletion of all associated rows in data tables NMS can create a new control row with the modified parameters 4

RMON MIB Table Mgmt (1) The RMON specification includes a set of textual conventions and procedural rules for row addition and deletion Textual conventions OwnerString ::= DisplayString EntryStatus ::= INTEGER { valid (1), createRequest (2), underCreation (3), invalid (4) } 4

RMON MIB Table Mgmt (2) Row Addition Row Deletion Row Modification is achieved by using the SNMP SetRequest PDU which includes instance objects and their values Row Deletion is achieved by setting the status object for that row to invalid Row Modification is achieved by first invalidating the row and then adding the row with new object instance values 4

Example Control & Data Tables rm1ControlTable rmlControlIndex rmlControlParameter rmlControlOwner rmlControlStatus 1 5 monitor valid (1) 2 26 manager alpha valid (1) 3 19 manager beta valid (1) rm1DataTable rmlDataControlIndex rmlDataIndex rmlDataValue 1 1 46 2 1 96 2 2 85 2 3 77 2 4 27 2 5 92 3 1 86 3 2 26 4

Transitions of EntryStatus State non- existent create Request under Creation valid performed by manager invalid performed by agent 4

RMON MIB rmon (mib-2 16) statistics (1) history (2) alarm (3) host (4) hostTopN (5) matrix (6) filter (7) capture (8) event (9) tokenRing (10) 4

RMON MIB Groups 1. statistics: maintains MAC-level utilization and error stats 2. history: records periodic statistical samples from the stats group 3. alarm: allows NMS to set sampling interval & alarm threshold 4. host: contains counters for traffic from hosts on the subnetwork 5. hostTopN: contains sorted host stats that top a list based on some parameter in the host table 6. matrix: shows utilization and error stats in matrix for host pairs 7. filter: allows the monitor to observe packets that match a filter 8. capture: specifies how data is sent to NMS 9. event: specifies events to be generated by the RMON probe 10. tokenRing: maintains stats & config info for token ring subnet 4

RMON MIB2 RMON MIB monitors MAC-level subnet traffic RMON MIB2 can monitor traffic of packets at layers 3 to 7 of the OSI Reference Model Provides Network-layer Visibility can distinguish between local LAN and remote LAN traffic Provides Application-layer Visibility can analyze traffic to and from hosts for particular applications can determine which applications are putting the load on the net RMON MIB2 is basically an extension of RMON MIB 4

RMON MIB2 rmon (mib-2 16) statistics (1) history (2) alarm (3) host (4) hostTopN (5) matrix (6) filter (7) capture (8) event (9) tokenRing (10) probeConfig (19) usrHistory (18) alMatrix (17) alHost (16) nlMatrix (15) nlHost (14) addressMap (13) protocolDist (12) protocolDir (11) RMON 1 RMON 2 4

RMON MIB2 Groups 11. protocolDir: a master directory of all of the protocols that the probe can interpret 12. protocolDist: aggregate stats on the amount of traffic generated by each protocol, per LAN segment 13. addressMap: contains MAC and port addresses of the devices 14. nlHost: network layer traffic stats per host 15. nlMatrix: network layer traffic stats per pairs of hosts 16. alHost: application layer traffic stats per host 17. alMatrix: application layer traffic stats per pairs of hosts 18. userHistory: periodically samples and logs user-defined data 19. probeConfig: defines standard configuration parameters for RMON probes 4

Summary RMON extends the SNMP functionality without changing the protocol RMON can monitor information on a whole subnetwork RMON is used extensively in analyzing network traffic for problem detection and network planning RMON2 allows monitoring of traffic at layers 3 to 7 in the OSI Model RMON2 can be used to analyze network traffic more accurately even to the application level Read Chapters 8, 9 and 10 4