5424 (8-SNMP).pdf

Chapter 8 

Configuring SNMP and RMON 

This chapter describes how to configure SNMP and RMON on the Corecess 5424. 

Configuring SNMP 8 -2 

This section introduces some basic information on SNMP and describes how to configure the 

SNMP on the Corecess 5424. 

Configuring RMON 8-18 

This section introduces some basic information on the RMON protocol and describes how to 

configure the RMON on the Corecess 5424. 

SNMP and RMON Configuration Commands 8-34 

This section lists the commands for configuring the SNMP and the RMON. 

Configuring SNMP and RMON 8-1

Configuring SNMP 

SNMP(Simple Network Management Protocol) Overview 

8-2 

The Simple Network Management Protocol (SNMP) is an application layer protocol that 

facilitates the exchange of management information between network devices. It is part of the 

Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite. SNMP enables 

network administrators to manage network performance, find and solve network problems, 

and plan for network growth. 

SNMP Basic Components 

SNMP consists of the following three key components: 

Managed Device 

SNMP Agent and Management Information Base (MIB) 

SNMP Manager 

Managed Device 

Managed 

Device 

SNMP Agent 

MIB 

A managed device is a network node that contains an SNMP agent and that resides on a 

managed network. Managed devices collect and store management information and make this 

information available to NMSs using SNMP. Managed devices, sometimes called network 

elements, can be routers and access servers, switches and bridges, hubs, computer hosts, or 

printers. 

Corecess 5424 User’s Guide 

SNMP 

Manager 

Managed 

Device 


MIB 

Managed 

Device 


MIB

SNMP Agent and MIB 

The SNMP agent is a network management module running in the managed device. The 

SNMP agent responds to SNMP manager requests as follows: 

Get a MIB variable: The SNMP agent initiates this function in response to a request from 

the NMS. The agent retrieves the value of the requested MIB variable and responds to 

the NMS with that value. 

Set a MIB variable: The SNMP agent initiates this function in response to a message from 

the NMS. The SNMP agent changes the value of the MIB variable to the value requested 

by the NMS. 

The SNMP agent also sends unsolicited trap messages to notify an NMS that a significant 

event has occurred on the agent. Examples of traps conditions include, but are not limited to, 

when a port or module goes up or down, when spanning-tree topology changes occur, and 

when authentication failures occur. 

The MIB is the information base, the SNMP agent must keep available for the managers. This 

information base contains objects whose values provide information on the status of the 

checked system or objects whose values can be modified by a manager to control the system. 

Each object is identified by an Object ID (OID). There are two kinds of MIBs, standard MIB 

and enterprise-specific MIB. 

SNMP Manager 

SNMP Manager is an integrated management module which collects information from SNMP 

agent and sometimes sends warning messages depending on the each SNMP agent relations. 

In other words, the actual data is collected from SNMP agent and this data will be processed 

by management module and saved. To request information or configuration changes, respond 

to requests, and send unsolicited alerts, the SNMP manger and SNMP agent use the four 

messages (Get, GetNext, Set, trap). For more information on these messages, refer to the 

following section. 


8-4 

SNMP Messages 

The SNMP manger and SNMP agent use the following SNMP messages to request 

information or configuration changes, respond to requests, and send unsolicited alerts. 

Get-Request / Get-Response Message 

GetNext-Request / GetNext-Request Message 

Set-Request Message 

Trap Message 

Get-Request Message 

Get-Request Message is the basic SNMP request message. Sent by an SNMP manager, it 

requests information about a single MIB entry on an SNMP agent. For example, the amount of 

free drive space. 

GetNext-Request Message 

GetNext-Request Message is an extended type of request message that can be used to browse 

the entire tree of management objects. When processing a Get-next request for a particular 

object, the agent returns the identity and value of the object which logically follows the object 

from the request. The Get-next request is useful for dynamic tables, such as an internal IP 

route table. 

Set-Request Message 

If write access is permitted, Set-Request message can be used to send and assign an updated 

MIB value to the agent. 

Trap Message 

An unsolicited message sent by an SNMP agent to an SNMP manager when the agent detects 

that a certain type of event has occurred locally on the managed device. For example, a trap 

message might be sent on a system restart event. 

Corecess 5424 User’s Guide

SNMP Community Strings 

SNMP community strings authenticate access to MIB objects and function as embedded 

passwords. In order for the NMS to access the system, the community string definitions on the 

NMS must match at least one of the three community string definitions on the system. 

A community string can have one of the following attributes: 

| Table 8-1 Types of community strings | 

Read-only 

Read-write 

Types Access Right 

Read-write-all 

Trap 

Gives read access to authorized management stations to all objects in the MIB 

except the community strings, but does not allow write access 

Gives read and write access to authorized management stations to all objects in the 

MIB, but does not allow access to the community strings 

Gives read and write access to authorized management stations to all objects in the 

MIB, including the community strings 

Trap is a defined status of event or system. For example, event generated when port 

configuration is changed or a host having not-allowed IP address accesses can be defined as a 

trap. You can configure the level of trap according to the kind of events. If a trap occurs on the 

system, the SNMP agent send SNMP trap message to the registered trap host. 


Configuring SNMP 

8-6 

SNMP Default Configuration 

The default SNMP configuration of the Corecess 5424 is as follows: 

| Table 8-2 Default SNMP configuration | 


SNMP Configuration Element Default Setting 

Agent contact information (MIB-II System Contact variable) None configured 

Agent location information (MIB-II System Location variable) None configured 

Community strings None configured 

Trap None enabled 

Trap Host None configured 

RMON Enabled 

Setting the System Contact and Location Information 

In the system group of MIB-II (Public MIB) supported by the Corecess 5424 has System Contact 

variable and System Location variable displaying the system contact information and system 

location information. 

The values of these variables can be browsed or modified via ViewlinX, NMS of the Corecess 

or NMS of other companies. To specify these values, use the following commands: 

| Table 8-3 Setting the system contact and location information | 

Command Task 

configure terminal 1. Enter Global configuration mode. 

snmp-server contact 

snmp-server location 

end 4. Return to Privileged mode. 

2. Set the system contact information. 

: String described for system contact information. 

3. Set the system location information. 

: String described for system location information. 

show snmp-server 5. Verify the system contact and location information.

The following is an example of setting the system contact information and system location 

information: 

Parameter Value 

System contact information TEL: +82-2-3016-6900 

System location information Daechi-dong Seoul Korea 

# configure terminal 

(config)# snmp-server contact "TEL:+82-2-3016-6900" 

(config)# snmp-server location "Daechi-dong Seoul Korea" 

(config)# end 

# show snmp-server 

RMON: Enabled 

Extended RMON: Extended RMON module is not present 

sysContact TEL:+82-2-3016-6900 

sysLocation Daechi-dong Seoul Korea 

... 

# 

Configuring Community Strings 

You use the SNMP community string to define the relationship between the SNMP manager 

and the agent. The community string acts like a password to permit access to the agent on the 

system. One thing to be aware of is that in case of adding new community string using the 

Corecess 5424 CLI command, this community string must be added in NMS in order to 

connect to the system using this community string. To define SNMP community strings, use 

the following commands in Privileged mode: 

| Table 8-4 Configuring SNMP community strings | 

Command Task 


snmp-server community 

 

 


show snmp-server 

community-list 

2. Define the SNMP community strings for each access type. 

: The SNMP community name for this system. 

Enter an unquoted text string with no space and a maximum length 

of 12 characters. 

: Access type for this community (read-only, read-write) 

4. Verify new community string. 


8-8 

The following example defines new community string: 


(config)# snmp-server community cc5424 rw 

(config)# end 


RMON: Enabled 


sysContact Dial System Administrator at phone #2734 

sysLocation 1st_floor_lab 

Community-Access Community-String 

---------------- ---------------- 

read-write cc5424 

... 

# 

To delete a community string, use the no snmp-server community command in Global 

configuration mode as follows: 

(config)# no snmp-server community cc5424 

(config)# end 

# show snmp-server community-list 

# 

Configuring Trap Host 

Trap host is the host to receive traps from an SNMP agent. Trap is message sent by an SNMP 

agent to an NMS, a console, or a terminal to indicate the occurrence of a significant event, such 

as a specifically defined condition or a threshold that was reached. By default, no trap host is 

configured. To receive the trap generated on your managed device using NMS, you must add 

the NMS as a trap host. You can specify up to twenty trap hosts on the Corecess 5424. 


To add or modify trap hosts, use the following commands in Privileged mode: 

| Table 8-5 Configuring a trap host | 

Command Task 


snmp-server host 

port 


show snmp-server traphost 4. Verify the trap host entries 

The following example shows how to add a trap host: 

2. Add a trap host. 

: The IP address or host name of an SNMP 

host that has been configured to receive traps. 

: The community name to use when 

sending traps to the specified SNMP host. 

: The UDP port number to use when sending 

traps to the specified SNMP host (1 ~ 65535, default 

setting: 165). 


(config)# snmp-server host 172.168.2.23 cc5424 port default 

(config)# end 


RMON: Enabled 


: 

Trap-Rec-Address Trap-Rec-Community 

------------------------- ------------------ 

udp:172.168.2.23:162 cc5424 

: 

# 

To delete a trap host, use the no snmp-server host command in Global configuration 

mode. The following example deletes a trap host 172.168.2.23: 

(config)# no snmp-server host 168.28.1.1 

(config)# end 

# show snmp-server traphost 

# 


8-10 

Configuring Trap Type 

Traps are system alerts that the Corecess 5424 generates when certain events occur. The 

Corecess 5424 supports the following trap types: 

| Table 8-6 Types of trap supported by Corecess 5424 | 

Trap Types Description 

chassis 


Sends a trap message when power supply is installed or uninstalled, 

temperature limitations are exceeded, or fan errors occur. 

module Sends a trap message when a module goes up or down. 

port Sends a trap message when a port goes up or down. 

bridge 

Sends a trap message when there are spanning tree topology 

changes. 

repeater Sends a trap message when Ethernet hub repeater state is changed. 

ip_permit 

sysconfig 

entity 

auth 

sysauth 

Sends a trap message when there are access attempts with 

unauthorized IP address. 

Sends a trap message when the system backup configuration is 

changed. 

Sends a trap message when there is Entity Management Information 

Base (MIB) change. 

Sends a trap message when there are access attempts with 

unauthorized community string. 

Sends a trap message when unauthorized user attempts access to the 

system. 

cpuload Sends a trap message when CPU load limitations are exceeded. 

bgp 

dhcp 

Sends a trap message when Border Gateway Protocol (BGP) state is 

changed. 

Sends a trap message when Dynamic Host Configuration Protocol 

(DHCP) state is changed. 

When a trap is enabled, if an error occurs in the device where corresponding trap is enabled or 

if problem occurs in the part defined by the trap, such error status (trap message) are 

transmitted to the trap receiving host and NMS, the SNMP agent. By default, all trap types are 

disabled. To send traps to the trap hosts, the trap types should be enabled.

To enable a trap type, use the following commands in Privileged mode: 

| Table 8-7 Enabling a trap type | 

Command Task 


snmp-server enable traps 

 

2. Enable the specified trap type. 

: Trap type to be enabled (all: all trap types). 


show snmp-server 4. Check the state of the trap. 

The following example enables the port and auth traps: 


(config)# snmp-server enable traps port 

(config)# snmp-server enable traps auth 

(config)# end 


RMON: Enabled 


: 


------------------------- ------------------ 

Traps Enabled 

------------------------- ------------------ 

chassis disabled 

module disabled 

port enabled 

bridge disabled 

repeater disabled 

ip_permit disabled 

sysconfig disabled 

entity disabled 

cpuload disabled 

auth enabled 

sysauth disabled 

bgp disabled 

dhcp disabled 

atm disabled 

# 

To disable the trap type, use the no snmp-server enable traps command as follows: 

(config)# no snmp-server enable traps port 


8-12 

Configuring SNMP Access Groups 

You can configure an SNMP access group by using access lists. The hosts that are permitted in 

the access lists can access to the system via SNMP. 

To configure SNMP access group by using access lists, use the following commands in 

Privileged mode: 

| Table 8-8 Configuring SNMP acess groups | 

Command Task 


snmp-server enable traps 

 


2. Configure a new SNMP access group. 

: Standard access list number (1 ~ 99, 100 ~ 199) 

The following example shows how to configure a SNMP access group: 

(config)# access-list 12 permit 192.89.55.0 0.0.0.255 

(config)# snmp-server group access 12 

(config)# 

The hosts that belong to 192.89.55.0 network can access to the system via SNMP.

Displaying SNMP Information 

The section describes how to display SNMP configuration information, SNMP community 

strings, SNMP trap hosts, and SNMP statistics. 

Displying SNMP Configuration Information 

To display SNMP configuration information, use the show snmp-server command in 

Privileged mode. 

The following example is a sample output of the show snmp-server command: 


RMON: Disabled 


sysContact support@corecess.com 

sysLocation Unknown 

Community-Access Community-String 

---------------- ---------------- 

read-only public 

read-write private 

read-only corecess 


------------------------- ------------------ 

udp:172.27.2.36:162 

Traps Enabled 

------------------------- ------------------ 

chassis disabled 

module disabled 

port disabled 

bridge disabled 

repeater disabled 

ip_permit disabled 

sysconfig disabled 

entity disabled 

cpuload disabled 

auth disabled 

sysauth disabled 

bgp disabled 

dhcp disabled 

atm disabled 

# 


8-14 

The table below describes the fields shown by the show snmp-server command: 

| Table 8-9 show snmp-server field descriptions | 

RMON 

Extended RMON 


Field Description Default 

Status of whether RMON is enabled or 

disabled 

Status of whether extended RMON is 

enabled or disabled 

enabled 

not supported 

sysContact SNMP system contact string unknown 

sysLocation SNMP system location string unknown 

community 

TrapReceiver 

Trap 

Community-Access 

Community-String 

Trap-Rec-Address 

Trap-Rec-Community 

Traps Trap types 

Enabled 

Displaying SNMP Community Strings 

Configured SNMP communities 

- read-only 

- read-write 

SNMP community strings associated with 

each SNMP community 

IP address of trap receiver hosts and UDP 

port number for sending trap messages. 

SNMP community string used for trap 

messages to the trap receiver. 

Status of whether trap type is enabled or 

disabled 

none 

disabled 

To display SNMP community strings, use the show snmp-server community-list 

command in Privileged mode. 

The following example shows how to display SNMP community strings: 

# show snmp-server community-list 

community:pubilc access: ro 

community:private access: rw 

community:corecess access: ro 

# 

The table below describes the fields shown by the show snmp-server community-list 

command output:

| Table 8-10 show snmp-server community-list field descriptions | 

Field Description 

community SNMP community strings 

access 

Displaying SNMP Statistics 

Access right of the community strings 

- ro : Read-only 

- rw : Read-write 

To display SNMP statistics, use the show snmp-server statistics command in 

Privileged mode. 

The following is sample output from the show snmp-server statistics command: 

# show snmp-server statistics 

10090 SNMP packets input 

0 Bad SNMP version errors 

96 Unknown community name 

0 Illegal operation for community name supplied 

0 Encoding errors 

28051 Number of requested variables 

12 Number of altered variables 

9854 Get-request PDUs 

83 Get-next PDUs 

12 Set-request PDUs 

9994 SNMP packet output 

0 Too big errors (Maximum packet size 1500) 

3 No such name errors 

0 Bad values errors 

0 General errors 

9994 Response PDUs 

0 Trap PDUs 

# 


8-16 

The table below describes the fields shown by the show snmp-server statistics 

command output: 

| Table 8-11 show snmp-server statistics field descriptions | 


SNMP packets input Total number of SNMP packets input. 

Bad SNMP version errors Number of packets with an invalid SNMP version. 

Unknown community name Number of SNMP packets with an unknown community name. 

Illegal operation for 

community name supplied 


Number of packets requesting an operation not allowed for that 

community. 

Encoding errors Number of SNMP packets that were improperly encoded. 

Number of requested 

variables 

Number of variables requested by SNMP managers. 

Number of altered variables Number of variables altered by SNMP managers. 

Get-request PDUs Number of get requests received. 

Get-next PDUs Number of get-next requests received. 

Set-request PDUs Number of set requests received. 

SNMP packet output Total number of SNMP packets sent by the router. 

Too big errors 

No such name errors 

Bad values errors 

General errors 

Number of SNMP packets which were larger than the maximum 

packet size. 

Number of SNMP requests that specified an MIB object which does 

not exist. 

Number of SNMP set requests that specified an invalid value for an 

MIB object. 

Number of SNMP set requests that failed due to some other error. (It 

was not a noSuchName error, badValue error, or any of the other 

specific errors.) 

Response PDUs Number of responses sent in reply to requests. 

Trap PDUs Number of SNMP traps sent.

Displaying SNMP Trap Hosts 

To display the list of the trap receiver hosts, use the show snmp-server traphost 

command in Privileged mode. 

The following example shows how to display the list of the trap receiver hosts: 

# show snmp-server traphost 

host: udp:172.27.2.36:162 comm: public 

host: udp:172.28.3.178:24 comm: corecess 

# 

The table below describes the fields shown by the show snmp-server traphost 

command output: 

| Table 8-12 show snmp-server traphost field descriptions | 


host Protocol : IP address of a trap receiver host: port number. 

comm SNMP community strings of the trap receiver host. 


Configuring RMON 

RMON (Remote MONitoring) Overview 

8-18 

The RMON is a standard MIB that defines current and historical MAC-layer statistics and 

control objects, allowing you to capture real-time information across the entire network. The 

RMON standard is an SNMP MIB definition described in RFC 1757 (formerly 1271) for 

Ethernet. 

The RMON MIB provides a standard method to monitor the basic operations of the Ethernet, 

providing inoperability between SNMP management stations and monitoring agents. The 

RMON also provides a powerful alarm and event mechanism for setting thresholds and for 

notifying you of changes in network behavior. 

You can use the RMON to analyze and monitor network traffic data within remote LAN 

segments from a central location. This allows you to detect, isolate, diagnose, and report 

potential and actual network problems before they escalate to crisis situations. For example, 

the Corecess 5424 can identify the hosts on a network that generate the most traffic or errors. 

The RMON allows you to set up automatic histories, which the RMON agent collects over a 

period of time, providing trending data on such basic statistics as utilization, collisions, and so 

forth. 

The RMON monitors nine MIB groups including network statistics. The following table lists 

the RMON MIB groups: 

| Table 8-13 RMON groups | 

Group Description 

1. Statistics Collects the network statistics. 

2. History Records the network activity in sequence of time. 

3. Alarm Defines level of the alarms to be informed to the manager. 

4. Host Monitors the hosts in the network. 

5. Host Top N Filters and manages the information of N hosts. 

6. Matrix Monitors the traffics between network nodes. 

7. Filter Monitors the specified packets on the network segment. 

8. Packet Capture 

Creates capture buffers and controls how the buffers are filled and how 

much of each packet is stored. 

9. Event Determines the action to take when an event is triggered by an alarm. 


The Corecess 5424 supports the following four groups among the nine groups: 

1) Statistics (RMON group 1) 

Collects the number of packets/bytes, the number of broddcast/multicast packets, the 

number of collisions, the number of errors occurred (fragment, CRC, jabber, short-length, 

long-length) on an interface. 

2) History (RMON group 2) 

Collects a history group of statistics on Ethernet, Fast Ethernet, and Gigabit Ethernet 

interfaces for a specified polling interval 

3) Alarm (RMON group 3) 

Monitors a specific management information base (MIB) object for a specified interval, 

triggers an alarm at a specified value (rising threshold), and resets the alarm at another 

value (falling threshold). Alarms can be used with events; the alarm triggers an event, 

which can generate a log entry or an SNMP trap 

4) Event (RMON group 9) 

Determines the action to take when an event is triggered by an alarm. The action can be to 

generate a log entry or an SNMP trap. 


Configuring RMON 

8-20 

Enabling RMON 

To enable RMON, perform this task in Privileged mode: 

| Table 8-14 Enabling RMON | 

Command Task 


snmp-server enable rmon 2. Enable the RMON on the Corecess 5424. 


show snmp-server 4. Verify that RMON is enabled. 

This example shows how to enable the RMON on the Corecess 5424 and how to verify that 

RMON is enabled: 


(config)# snmp-server enable rmon 

(config)# end 


RMON: Enabled 


sysContact TEL:+82-2-3016-6900 

sysLocation Daechi-dong Seoul Korea 

... 


Configuring Statistics Groups 

The RMON Statistics group records data that the Ethernet DCM measures on network 

interfaces. The Ethernet DCM creates one entry for each Ethernet interface it monitors and 

places the entry in the EtherStatsTable. The EtherStatsTable also contains control parameters 

for this group. 

To configure an RMON statistics group, use the following commands in Global configuration 

mode: 

| Table 8-15 Configuring RMON statistics group | 

Command Task 


rmon etherstats 

 

owner 

 

2. Set a statistics group. 

: RMON statistics group number (1 ~ 65535) 

: The data source object for the Ethernet port. The port is 

identified by an ifIndex data object identifier. To see a list of data 

object IDs, use the show interface command. 

owner : option for specifying an owner who 

defined and is using the statistics resources 


show rmon 4. Verify the configuration. 

The following is an example of configuring a statistics group: 


Statistics group No. 1 

Interface ID 5 

Owner 172.1.1.1 


(config)# rmon etherstats 1 5 owner kd_hong 

(config)# end 

# show rmon 

RMON memory: 30% 

[statistics] 

etherStatsIndex etherStatsOwner etherStatsStatus 

------------------- ------------------- -------------------- 

1 172.1.1.1 valid 

. . . 


8-22 

Configuring History Groups 

The RMON History group contains a control and data collection function. The control 

function manages the periodic statistical sampling of data from networks and specifies control 

parameters, such as the frequency of data sampling, in the historyControlTable. The history 

function records periodic statistical samples from Ethernet networks, for example, interval 

start time and number of packets. This function places the statistical samples in the 

etherHistoryTable. 

You can configure the operation of the RMON history that periodically samples any Ethernet 

port for statistical data. All ports are preconfigured with histories for 30-second and 30-minute 

intervals, and 50 buckets with one sample per bucket. However, you can create additional 

histories for a specific port. This allows you to configure the time interval to take the sample 

and the number of samples you want to save. 

To configure an RMON history group, use the following commands in Global configuration 

mode: 

| Table 8-16 Configuring RMON history group | 

Command Task 


rmon historycontrol 

{ | 

 

/} owner 

 

 

 




2. Set a history group. 

: RMON history number (1 ~ 65535) 

: Interface number (1 ~ 2147483647) 

: Port type (fastethernet, gigabitethern) 

/ : Slot number/port number 

: MIB object monitoring interval (1-2147483647 seconds) 

: The data source object for the Ethernet port. The port is 

identified by an ifIndex data object identifier. To see a list of data 

object IDs, use the show interface command. 

owner : option for specifying an owner who defined 

and is using the history resources 

: The bucket count for the interval (1 ~ 65535) 

: The time interval for the history (1 ~ 3600 

seconds)

The following is an example of configuring a history group: 


(config)# rmon historycontrol 1 gigabitethernet 1/1 owner aaa 50 30 

(config)# end 

# show rmon 

RMON: Enabled 


[statistics] 

index status dataSource 

----- -------------- ----------------------------- 

[history] 


----- -------------- ----------------------------- 

1 valid ifIndex.1 (Gi 1/1) 

. 

. 

# 

To display the detail information on a history group, enter the show rmon history 

command with the history number: 

# show rmon history 1 

Entry 1 is valid, and owned by aaa 

Monitors ifEntry.ifIndex.1 every 10 seconds 

Requested # of time intervals, is buckets, is 10 

Granted # of time intervals, is buckets, is 10 

Sample # 6878 began measuring at 1days 18h:5m:52s:44th(15155244) 

Received 0 octets, 0 packets, 

0 broadcast and 0 multicast packets, 

0 undersized and 0 oversized packets, 

0 fragments and 0 jabbers, 

0 CRC alignment errors and 0 collisions. 

# of dropped packet events is 0 

Network utilization is estimated at 0 

. 

. 

. 

Sample # 6887 began measuring at 1days 18h:7m:22s:44th(15164244) 


8-24 

# 

Received 0 octets, 0 packets, 

0 broadcast and 0 multicast packets, 

0 undersized and 0 oversized packets, 

0 fragments and 0 jabbers, 

0 CRC alignment errors and 0 collisions. 

# of dropped packet events is 0 

Network utilization is estimated at 0 

To delete a history group, enter the no rmon historycontrol command in Global 

configuration mode: 

(config)# no rmon historycontrol 1 

(config)# 


Configuring Alarm Groups 

The RMON Alarm group allows you to set an alarm threshold and a sampling interval to 

enable the RMON agent to generate alarms on any network segment it monitors. Alarm 

thresholds can be based on ‘absolute’ or ‘delta’ values so that you can be notified of rapid 

spikes or drops in a monitored value. 

Each alarm is linked to an event in the event group. An event defines an action that will be 

triggered when the alarm threshold is exceeded. 

The alarm group periodically takes statistical samples from variables and compares them to 

previously configured thresholds. The Alarm Table stores configuration entries that define a 

variable, a polling period, and threshold parameters. If the RMON agents determines that a 

sample crosses the threshold values, it generates an event. You can specify rising or falling 

thresholds, indicating network faults such as slow throughput or other network-related 

performance problems. You specify rising thresholds when you want to be notified that an 

alarm has risen above the threshold you specified. You specify falling thresholds when you 

want to be notified that the network is behaving normally again. For example, you might 

specify a falling threshold of 30 collisions per second to indicate a return to acceptable 

behavior. 

When you configure an alarm condition, you must define the following values: 

The monitoring interval over which data is sampled. 

The variable to be sampled. 

Rising and falling thresholds used to detect when network trouble starts and when it ends. 

The event that takes place when a rising threshold is crossed. 

The event that takes place when a falling threshold is crossed. 

An RMON event is the action that occurs when an associated RMON alarm is triggered. When 

an alarm event occurs, it can be configured to generate a log event, a trap to an SNMP network 

management station, or both. For information on viewing alarm events in log files. 

An RMON alarm allows you to monitor a MIB object for a desired transitory state. An alarm 

periodically takes samples of the object's value and compares them to the configured 

thresholds. 


8-26 

RMON allows you to configure two types of sampling, absolute and delta: 

Absolute sampling compares the sample value directly to the threshold. This sampling is 

similar to a gauge, recording values that go up or down. 

Delta sampling subtracts the current sample value from the last sample taken, and then 

compares the difference to the threshold. This sampling is similar to a counter, recording a 

value that is constantly increasing. 

To set an RMON alarm, use the following commands in Privileged mode: 

|Table 8-12 Configuring RMON alarm group | 

Command Task 


rmon alarm 

{ 

 

|} 

{delta | absolute} 

{rising | falling | 

both} threshold 

 

 

event-index owner 

 


2. Set an alarm on a MIB object. 

: Alarm number (1 ~ 65535) 

: MIB object monitoring interval (1-2147483647 seconds) 

: Value to monitor. Select one of the following values: 

- multicastPkts: The number of incoming multicast packets. 

- cRCAlignErrors: The number of incoming packets with CRC errors. 

- collisions: The number of times a collision occurs while the packet is 

received. 

- octets: The total number of incoming octets. 

- pkts: The total number of incoming packets. 

- broadcastPkts: The number of incoming broadcast packets 

- pkts256to511: The number of incoming packets 256 to 511 bytes in 

length. 


length. 

- pkts1024to1518: The number of incoming packets 1024 to 1518 bytes 

in length. 

- pkts64: The number of incoming packets 64 bytes in length 


length. 


length. 

: The number of statistics group to get the 

selected value from option (0 ~ 65535). 

: OID number of the MIB object to monitor. 

absolute: Option for testing each MIB variable directly. 

delta: Option for testing the change between MIB variables 

rising: Option for triggering alarm when the monitored value 

exceeds the rising threshold 

falling: Option for triggering alarm when the monitored value 

exceeds the falling threshold 

rising_or_falling: Option for triggering alarm when the monitored 

value exceeds the rising or falling threshol

(Continued) 

Command Task 



rising-threshold : Value at which the alarm is triggered (0 

~ 2147483647) 

falling-threshold : Value at which the alarm is reset (0 ~ 

2147483647) 

rising-event-index : Event number to trigger 

when the rising threshold exceeds its limit. (0 ~ 65535) 

falling-event-index : Event number to trigger 

when the falling threshold exceeds its limit. (0 ~ 65535) 

owner : option for specifying an owner for the 

alarm. 

The following example shows how to configure RMON alarm group and check the result: 


(config)# rmon alarm 1 10 pkts 1 absolute both threshold 1000 100 event-index 

1 1 owner aaa 

(config)# end 

# show rmon 

RMON: Enabled 


[statistics] 


----- -------------- ----------------------------- 


[history] 


----- -------------- ----------------------------- 


[alarm] 

index status sample 

----- -------------- ----------------------------- 

1 valid etherStatsPkts.1 

[event] 

index status type 

----- -------------- --------------- 

10 valid logandtrap 


8-28 

. 

. 

# 

Before configure RMON alarm group, you should verify that the statistics group 

() is defined. If you specify undefined statistics group, the ‘Can't fetch 

the MIB values’ message will be displayed: 

(config)# rmon alarm 2 20 pkts 10 absolute rising threshold 1000 100 eventindex 

1 1 owner kimka 

Can't fetch the MIB values 

(config)# 

To display the detail information on an alarm group, enter the show rmon alarm command 

with the alarm number: 

# show rmon alarm 1 

Alarm 1 is valid, owned by aaa 

Monitors etherStatsEntry.etherStatsPkts.1 every 10 seconds 

Taking absolute samples, last value was 0 

Rising threshold is 1000, assigned to event 1 

Falling threshold is 100, assigned to event 1 

On startup enable rising or falling alarm 

# 

To delete a RMON alarm group, enter the no rmon alarm command in Global configuration 

mode: 

(config)# no rmon alarm 1 

(config)# 


Configuring Event Groups 

The RMON Event group allows for the generation of an SNMP trap, the generation of a log entry, 

or both, for any event you choose. An event can occur when the sample variable exceeds the 

alarm threshold or a channel match event generated. Traps can be delivered by the RMON 

agent to multiple management stations. 

In order for RMON to generate trap events, you must set up the SNMP managers table based 

on the SNMP community strings (for example, public) you are using with the network 

management application and the hosts on which you are running applications. If you fail to 

make these changes, the system will be unable to send trap events to the network 

management station. 

When you set up the SNMP managers table, you can use the SNMP community strings that 

the network management application uses and modify the trap receiving tables on the router 

to use these names. Or, you can configure the router to use specific SNMP community strings 

and modify the network management software to use these strings. 

To set an RMON event, use the following commands in Privileged mode: 

| Table 8-13 Configuring RMON event group | 

Command Task 


rmon event 

description 

{trap | 

log } owner 



2 Add or remove an event in the RMON event table. 

: Assigned event number (1 ~ 65535). 

description : A description of the event. 

log: Option for generating an RMON log entry when the event is 

triggered 

trap : Option for generating SNMP trap with the 

community string when the event occurs. 

owner : Option for specifying an owner for the event. 


8-30 

This example shows how to configure an event group on the Corecess 5424 and how to verify 

that they are configured: 


Event index 10 

Event description Event to create log entry and SNMP notification 

Event type log, trap 

Community public 

Owner help_desk 


(config)# rmon event 10 description “Event to create log entry and SNMP 

notification” log trap public owner help_desk 

(config)# end 

# show rmon 

RMON: Enabled 


[statistics] 


----- -------------- ----------------------------- 


2 valid ifIndex.3 (Fa 3/1) 

[history] 


----- -------------- ----------------------------- 


[alarm] 


----- -------------- ----------------------------- 

[event] 


----- -------------- --------------- 

10 

. 

. 

# 

valid logandtrap 


To display the detail information on an event group, enter the show rmon events 

command with the event number: 

# show rmon events 1 

# show rmon events 10 

Event 10 is valid, owned by help_desk 

Description is Event to create log entry and SNMP notification 

Event firing causes log and trap to community public 

last fired 0days 00:00:00:00 

Event 2 is valid, owned by 172.1.1.1 

Description is High_trap 

Event firing causes trap to community corecess 

last fired 0days 0h:0m:30s:73th(3073) 

Event 10 is valid, owned by help_desk 

Description is Event to create log entry and SNMP notification 

Event firing causes log and trap to community public 

last fired 0days 00:00:00:00 

# 

To delete an event group, enter the no rmon event command in Global configuration mode: 

(config)# no rmon event 10 

(config)# 


Displaying RMON Information 

8-32 

To display the current RMON configuration, enter the show rmon command in Privileged 

mode. You can execute the show rmon command with the following options: 

alarm Displays the RMON alarm table. 

events Displays the RMON event table. 

history Displays the RMON history table. 

statistics Displays the RMON statistics table. 

If you do not specify any option, the contents of the RMON alarm table, event table, history table, and 

statistics table are displayed. The following is a sample output of the show rmon command: 

# show rmon 

RMON: Enabled 


[statistics] 


----- -------------- ----------------------------- 


[history] 


----- -------------- ----------------------------- 


[alarm] 


----- -------------- ----------------------------- 

1 valid etherStatsPkts.1 

[event] 


----- -------------- --------------- 

10 

# 

valid logandtrap 


The table below describes the fields in the show rmon command output: 

| Table 8-18 show rmon field descriptions | 


RMON Running status of the RMON. 

statistics 

history 

alarm 

event 

Index Index of the RMON statistics entry into the statisticsTable. 

Status Status of the RMON statistics entry. 

dataSource Data source of the RMON statistics entry. 

Index Index of the RMON history entry into the historyTable. 

Status Status of the RMON history entry. 

dataSource Data source of the RMON history entry. 

Index Index of the RMON alarm entry into the alarmTable. 

Status The owner of the RMON alarm entry. 

Sample Data source of the RMON alarm entry. 

Index Index of the RMON event entry into the eventTable. 

Status Status of the RMON event entry. 

Type Type of event. 


SNMP and RMON Configuration Commands 

8-34 

The table below shows the list of SNMP and RMON configuration commands and their 

functions. 

| Table 8-14 SNMP & RMON Configuration Commands | 

Command Function 

show snmp-server Displays SNMP parameters. 

show snmp-server community-list Displays SNMP community configuration. 

show snmp-server statistics Displays SNMP statistics. 

show snmp-server traphost Displays the list of the trap receiver hosts. 

show rmon 


Displays the contents of the RMON alarm table, event table, 

history table, and statistics table. 

snmp-server community Configures the SNMP community strings. 

snmp-server contact Specifies the system contact information. 

snmp-server enable rmon Enables the RMON. 

snmp-server enable traps Enables a SNMP trap. 

snmp-server group access 

Limits hosts which can access to the system through SNMP based 

on the access list. 

snmp-server host Specifies hosts to receive SNMP notifications. 

snmp-server location Specifies the system location information.. 

rmon alarm Configure an RMON alarm group. 

rmon etherstats Configures an RMON statistics group. 

rmon event Configures an RMON event group. 

rmon historycontrol Configures an RMON history group.

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