Configuring SNMP· 1

Overview·· 1

SNMP framework· 1

MIB and view-based MIB access control 1

SNMP operations 2

SNMP protocol versions 2

SNMP configuration task list 2

Configuring SNMP basic parameters 3

Configuring SNMPv3 basic parameters 3

Configuring SNMPv1 and SNMPv2c basic parameters 4

Configuring SNMP logging· 5

Configuring SNMP traps 6

Enabling SNMP traps 6

Configuring the SNMP agent to send traps to a host 7

Displaying and maintaining SNMP· 8

SNMP configuration examples 9

SNMPv1/SNMPv2c configuration example· 9

SNMPv3 configuration example· 11

SNMP logging configuration example· 12

Configuring MIB style· 1

Overview·· 1

Setting the MIB style· 1

Displaying and maintaining MIB· 1

 

 

Overview

The Simple Network Management Protocol (SNMP) is an Internet standard protocol widely used for a management station to access and operate the devices on a network, regardless of their vendors, physical characteristics and interconnect technologies.

SNMP enables network administrators to read and set the variables on managed devices for state monitoring, troubleshooting, statistics collection, and other management purposes.

SNMP framework

The SNMP framework comprises the following elements:

·           SNMP manager—Works on a network management system (NMS) to monitor and manage the SNMP-capable devices in the network.

·           SNMP agent—Works on a managed device to receive and handle requests from the NMS, and send traps to the NMS when some events, such as interface state change, occur.

·           Management Information Base (MIB)—Specifies the variables (for example, interface status and CPU usage) maintained by the SNMP agent for the SNMP manager to read and set.

Figure 1 Relationship between an NMS, agent and MIB

 

MIB and view-based MIB access control

A MIB stores variables called “nodes” or “objects” in a tree hierarchy and identifies each node with a unique OID. An OID is a string of numbers that describes the path from the root node to a leaf node. For example, the object B in Figure 2 is uniquely identified by the OID {1.2.1.1}.

Figure 2 MIB tree

 

A MIB view represents a set of MIB objects (or MIB object hierarchies) with certain access privilege and is identified by a view name. The MIB objects included in the MIB view are accessible while those excluded from the MIB view are inaccessible.

A MIB view can have multiple view records each identified by a view-name oid-tree pair.

You control access to the MIB by assigning MIB views to SNMP groups or communities.

SNMP operations

SNMP provides the following basic operations:

·           Get—The NMS retrieves SNMP object nodes in an agent MIB.

·           Set—The NMS modifies the value of an object node in the agent MIB.

·           Trap—The SNMP agent sends traps to report events to the NMS.

·           Notifications—Includes traps and informs. SNMP agent sends traps or informs to report events to the NMS. The difference between these two types of notification is that informs require acknowledgement but traps do not. The device supports only traps.

SNMP protocol versions

H3C supports SNMPv1, SNMPv2c, and SNMPv3.

·           SNMPv1 uses community names for authentication. To access an SNMP agent, an NMS must use the same community name as set on the SNMP agent. If the community name used by the NMS is different from the community name set on the agent, the NMS cannot establish an SNMP session to access the agent or receive traps and notifications from the agent.

·           SNMPv2c also uses community names for authentication. SNMPv2c is compatible with SNMPv1, but supports more operation modes, data types, and error codes.

·           SNMPv3 uses a user-based security model (USM) to secure SNMP communication. You can configure authentication and privacy mechanisms to authenticate and encrypt SNMP packets for integrity, authenticity, and confidentiality.

 

IMPORTANT: An NMS and an SNMP agent must use the same SNMP version to communicate with each other.

 

SNMP configuration task list

Complete the following tasks to configure SNMP:

 

Task	Remarks
Configuring SNMP basic parameters	Required
Configuring SNMP logging	Optional
Configuring SNMP traps	Optional

 

Configuring SNMP basic parameters

SNMPv3 differs from SNMPv1 and SNMPv2c in many aspects. Their configuration procedures are described in separate sections.

Configuring SNMPv3 basic parameters

To configure SNMPv3 basic parameters:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enable the SNMP agent.	snmp-agent	Optional. By default, the SNMP agent is disabled. You can also enable the SNMP agent by using any command that begins with snmp-agent except the snmp-agent calculate-password command.
3.      Configure SNMP agent system information.	snmp-agent sys-info { contact sys-contact | location sys-location | version { all | { v1 | v2c | v3 }* } }	Optional. By default, the contact is Hangzhou H3C Technologies Co., Ltd., the physical location is Hangzhou China, and the protocol version is SNMPv3.
4.      Configure the local engine ID.	snmp-agent local-engineid engineid	Optional. The default local engine ID is the company ID plus the device ID.
5.      Create or update a MIB view.	snmp-agent mib-view { excluded | included } view-name oid-tree [ mask mask-value ]	Optional. By default, the MIB view ViewDefault is predefined and its OID is 1.
6.      Configure an SNMPv3 group.	snmp-agent group v3 group-name [ authentication | privacy ] [ read-view read-view ] [ write-view write-view ] [ notify-view notify-view ] [ acl acl-number ]	By default, no SNMP group exists.
7.      Convert a plain text key to an encrypted key.	snmp-agent calculate-password plain-password mode { 3desmd5 | 3dessha | md5 | sha } { local-engineid | specified-engineid engineid }	Optional.
8.      Add a user to an SNMP agent group.	snmp-agent usm-user v3 user-name group-name [ [ cipher ] authentication-mode { md5 | sha } auth-password [ privacy-mode { 3des | aes128 | des56 } priv-password ] ] [ acl acl-number ]	If the cipher keyword is specified, the arguments auth-password and priv-password are used as encrypted keys.
9.      Configure the maximum SNMP packet size (in bytes) that the SNMP agent can handle.	snmp-agent packet max-size byte-count	Optional. By default, the SNMP agent can receive and send SNMP packets up to 1500 bytes.

 

NOTE: ·       After you change the local engine ID, the existing SNMPv3 users become invalid, and you must re-create the SNMPv3 users. ·       Each view-name oid-tree pair represents a view record. If you specify the same record with different MIB subtree masks multiple times, the last configuration takes effect. Except for the four subtrees in the default MIB view, you can create up to 16 unique MIB view records.

 

Configuring SNMPv1 and SNMPv2c basic parameters

To configure SNMPv1 and SNMPv2c basic parameters:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enable the SNMP agent.	snmp-agent	Optional. Disabled by default. You can also enable the SNMP agent by using any command that begins with snmp-agent except the snmp-agent calculate-password command.
3.      Configure SNMP agent system information.	snmp-agent sys-info { contact sys-contact | location sys-location | version { all | { v1 | v2c | v3 }* } } snmp-agent sys-info { contact sys-contact | location sys-location | version { all | { v1 | v2c | v3 } * } }	By default, the contact is Hangzhou H3C Technologies Co., Ltd., the physical location is Hangzhou China, and the protocol version is SNMPv3.
4.      Configure the local engine ID.	snmp-agent local-engineid engineid	Optional. The default local engine ID is the company ID plus the device ID.
5.      Create or update a MIB view.	snmp-agent mib-view { excluded | included } view-name oid-tree [ mask mask-value ]	Optional. By default, the MIB view ViewDefault is predefined and its OID is 1.
6.      Configure SNMP access right.	·       (Approach 1) Create an SNMP community: snmp-agent community { read | write } community-name [ acl acl-number | mib-view view-name ]* ·       (Approach 2) Create an SNMP group, and add a user to the SNMP group: a.   snmp-agent group { v1 | v2c } group-name [ read-view read-view ] [ write-view write-view ] [ notify-view notify-view ] [ acl acl-number ] b.   snmp-agent usm-user { v1 | v2c } user-name group-name [ acl acl-number ]	Use either approach. By default, no SNMP group exists. In approach 2, the username is equivalent to the community name in approach 1, and must be the same as the community name configured on the NMS.
7.      Configure the maximum SNMP packet size (in bytes) that the SNMP agent can handle.	snmp-agent packet max-size byte-count	Optional. By default, the SNMP agent can receive and send the SNMP packets up to 1,500 bytes.

 

NOTE: Each view-name oid-tree pair represents a view record. If you specify the same record with different MIB subtree masks multiple times, the last configuration takes effect. Except for the four subtrees in the default MIB view, you can create up to 16 unique MIB view records.

 

Configuring SNMP logging

The SNMP logging function logs the Get requests, Set requests, and Set responses that the NMS has performed on the SNMP agent, but does not log the Get responses.

·           For a Get operation, the agent logs the IP address of the NMS, name of the accessed node, and node OID.

·           For a Set operation, the agent logs the IP address of the NMS, name of the accessed node, node OID, the assigned value and the error code and error index of the Set response.

The SNMP module sends these logs to the information center as informational messages. You can output these messages to certain destinations, for example, the console and the log buffer by configuring the information center to output informational messages to these destinations. For more information about the information center, see the chapter “Configuring information center.”

To configure SNMP logging:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enable SNMP logging.	snmp-agent log { all | get-operation | set-operation }	By default, SNMP logging is disabled.

 

NOTE: ·       Disable SNMP logging in normal cases to prevent a large amount of SNMP logs from decreasing device performance. ·       The total output size for the node field (MIB node name) and the value field (value of the MIB node) in each log entry is 1024 bytes. If this limit is exceeded, the information center truncates the data in the fields.

 

Configuring SNMP traps

The SNMP agent sends traps to inform the NMS of important events, such as a reboot.

Traps fall into generic traps and vendor-specific traps. Available generic traps include authentication, coldstart, linkdown, linkup and warmstart. All other traps are vendor-defined.

SNMP traps generated by a module are sent to the information center. You can configure the information center to enable or disable outputting the traps from a module by their severity and set output destinations. For more information about the information center, see the chapter “Configuring information center.”

Enabling SNMP traps

Enable SNMP traps only when necessary. SNMP traps are memory-intensive and may affect device performance.

To enable traps:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enable traps globally.	snmp-agent trap enable [ acfp [ client | policy | rule | server ] | bfd | bgp | configuration | default-route | flash | mpls | ospf [ process-id ] [ ifauthfail | ifcfgerror | ifrxbadpkt | ifstatechange | iftxretransmit | lsdbapproachoverflow | lsdboverflow | maxagelsa | nbrstatechange | originatelsa | vifcfgerror | virifauthfail | virifrxbadpkt | virifstatechange | viriftxretransmit | virnbrstatechange ] * | pim [ candidatebsrwinelection | electedbsrlostelection | interfaceelection | invalidjoinprune | invalidregister | neighborloss | rpmappingchange ] * | standard [ authentication | coldstart | linkdown | linkup | warmstart ] * | system | vrrp [ authfailure | newmaster ] ]	By default, only the trap function of the voice module is disabled; and the trap function of other modules is enabled.
3.      Enter interface view.	interface interface-type interface-number	N/A
4.      Enable link state traps.	enable snmp trap updown	By default, link state traps are enabled.

 

NOTE: ·       To generate linkUp or linkDown traps when the link state of an interface changes, you must enable the linkUp or linkDown trap function globally by using the snmp-agent trap enable [ standard [ linkdown | linkup ] * ] command and on the interface by using the enable snmp trap updown command. ·       After you enable a trap function for a module, whether the module generates traps also depends on the configuration of the module. For more information, see the configuration guide for each module.

 

Configuring the SNMP agent to send traps to a host

Configuration prerequisites

·           Complete the basic SNMP settings and check that they are the same as on the NMS. If SNMPv1 or SNMPv2c is used, you must configure a community name. If SNMPv3 is used, you must configure an SNMPv3 user and MIB view.

·           The device and the NMS can reach each other.

Configuration procedure

The SNMP module buffers the traps received from a module in a trap queue. You can set the size of the queue, the duration that the queue holds a trap, and trap target (destination) hosts, typically the NMS.

To configure the SNMP agent to send traps to a host:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Configure a target host.	snmp-agent target-host trap address udp-domain { ip-address | ipv6 ipv6-address } [ udp-port port-number ] [ vpn-instance vpn-instance-name ] params securityname security-string [ v1 | v2c | v3 [ authentication | privacy ] ]	Optional. The vpn-instance keyword is applicable in an IPv4 network. To send the traps to the NMS, this command is required, and you must specify ip-address as the IP address of the NMS.
3.      Configure the source address for traps.	snmp-agent trap source interface-type interface-number	Optional. By default, SNMP chooses the IP address of an interface to be the source IP address of traps.
4.      Extend the standard linkUp/linkDown traps.	snmp-agent trap if-mib link extended	Optional. Standard linkUp/linkDown traps are used by default.
5.      Configure the trap queue size.	snmp-agent trap queue-size size	Optional. The default trap queue size is 100.
6.      Configure the holding time of the traps in the queue.	snmp-agent trap life seconds	Optional. 120 seconds by default.

 

NOTE: ·       Extended linkUp/linkDown traps add interface description and interface type to standard linkUp/linkDown traps. If the NMS does not support extended SNMP messages, use standard linkUp/linkDown traps. ·       When the trap queue is full, the oldest traps are automatically deleted for new traps. ·       A trap is deleted when its holding time expires.

 

Displaying and maintaining SNMP

 

Task	Command	Remarks
Display SNMP agent system information, including the contact, physical location, and SNMP version.	display snmp-agent sys-info [ contact | location | version ] * [ | { begin | exclude | include } regular-expression ]	Available in any view
Display SNMP agent statistics.	display snmp-agent statistics [ | { begin | exclude | include } regular-expression ]	Available in any view
Display the local engine ID.	display snmp-agent local-engineid [ | { begin | exclude | include } regular-expression ]	Available in any view
Display SNMP group information.	display snmp-agent group [ group-name ] [ | { begin | exclude | include } regular-expression ]	Available in any view
Display basic information about the trap queue.	display snmp-agent trap queue [ | { begin | exclude | include } regular-expression ]	Available in any view
Display the modules that can send traps and their trap status (enable or disable).	display snmp-agent trap-list [ | { begin | exclude | include } regular-expression ]	Available in any view
Display SNMPv3 user information.	display snmp-agent usm-user [ engineid engineid | username user-name | group group-name ] * [ | { begin | exclude | include } regular-expression ]	Available in any view
Display SNMPv1 or v2c agent community information.	display snmp-agent community [ read | write ] [ | { begin | exclude | include } regular-expression ]	Available in any view
Display MIB view information.	display snmp-agent mib-view [ exclude | include | viewname view-name ] [ | { begin | exclude | include } regular-expression ]	Available in any view

 

SNMP configuration examples

 

NOTE: By default, Ethernet, VLAN, and aggregate interfaces are down. To configure such an interface, bring the interface up by executing the undo shutdown command.

 

SNMPv1/SNMPv2c configuration example

Network requirements

As shown in Figure 3, the NMS (1.1.1.2/24) uses SNMPv1 or SNMPv2c to manage the SNMP agent (1.1.1.1/24), and the agent automatically sends traps to report events to the NMS.

Figure 3 Network diagram

 

Configuration procedure

1.       Configure the SNMP agent:

# Configure the IP address of the agent and make sure that the agent and the NMS can reach each other. (Details not shown)

# Specify SNMPv1 and SNMPv2c, and create a read-only community public and a read and write community private.

<Agent> system-view

[Agent] snmp-agent sys-info version v1 v2c

[Agent] snmp-agent community read public

[Agent] snmp-agent community write private

# Configure contact and physical location information for the agent.

[Agent] snmp-agent sys-info contact Mr.Wang-Tel:3306

[Agent] snmp-agent sys-info location telephone-closet,3rd-floor

# Enable SNMP traps, set the NMS at 1.1.1.2 as an SNMP trap destination, and use public as the community name. (To make sure that the NMS can receive traps, specify the same SNMP version in the snmp-agent target-host command as configured on the NMS.)

[Agent] snmp-agent trap enable

[Agent] snmp-agent target-host trap address udp-domain 1.1.1.2 params securityname public v1

[Agent] quit

2.       Configure the SNMP NMS:

# Configure the SNMP version for the NMS as v1 or v2c, create a read-only community and name it public, and create a read and write community and name it private. For how to configure the NMS, see the manual for the NMS.

 

NOTE: The SNMP settings on the agent and the NMS must match.

 

3.       Verify the configuration:

# Try to get the count of sent traps from the agent. The attempt succeeds.

Send request to 1.1.1.1/161 ...

Protocol version: SNMPv1

Operation: Get

Request binding:

1: 1.3.6.1.2.1.11.29.0

Response binding:

1: Oid=snmpOutTraps.0 Syntax=CNTR32 Value=18

Get finished

# Use a wrong community name to get a MIB node from the agent. You can see an authentication failure trap on the NMS.

1.1.1.1/2934 V1 Trap = authenticationFailure

SNMP Version = V1

Community = public

Command = Trap

Enterprise = 1.3.6.1.4.1.43.1.16.4.3.50

GenericID = 4

SpecificID = 0

Time Stamp = 8:35:25.68

SNMPv3 configuration example

Network requirements

As shown in Figure 4, the NMS (1.1.1.2/24) uses SNMPv3 to monitor and manage the interface status of the agent (.1.1.1/24), and the agent automatically sends traps to report events to the NMS.

The NMS and the agent perform authentication when they set up an SNMP session. The authentication algorithm is MD5 and the authentication key is authkey. The NMS and the agent also encrypt the SNMP packets between them by using the DES algorithm and the privacy key prikey.

Figure 4 Network diagram

 

Configuration procedure

1.       Configure the agent:

# Configure the IP address of the agent and make sure that the agent and the NMS can reach each other. (Details not shown)

# Assign the NMS (SNMPv3 group managev3group) read and write access to the objects under the snmp node (OID 1.3.6.1.2.1.11), and deny its access to any other MIB object.

<Agent> system-view

[Agent] undo snmp-agent mib-view ViewDefault

[Agent] snmp-agent mib-view included test snmp

[Agent] snmp-agent group v3 managev3group read-view test write-view test

# Add the user managev3user to the SNMPv3 group managev3group, set the authentication algorithm to MD5, authentication key to authkey, the encryption algorithm to DES56, and the privacy key to prikey.

[Agent] snmp-agent usm-user v3 managev3user managev3group authentication-mode md5 authkey privacy-mode des56 prikey

# Configure contact person and physical location information for the agent.

[Agent] snmp-agent sys-info contact Mr.Wang-Tel:3306

[Agent] snmp-agent sys-info location telephone-closet,3rd-floor

# Enable traps, specify the NMS at 1.1.1.2 as a trap destination, and set the username to managev3user for the traps.

[Agent] snmp-agent trap enable

[Agent] snmp-agent target-host trap address udp-domain 1.1.1.2 params securityname managev3user v3 privacy

2.       Configure the SNMP NMS:

¡  Specify the SNMP version for the NMS as v3.

¡  Create two SNMP users: managev3user and public.  

¡  Enable both authentication and privacy functions

¡  Use MD5 for authentication and DES for encryption.

¡  Set the authentication key to authenkey and the privacy key to prikey.

¡  Set the timeout time and maximum number of retries.

For information about configuring the NMS, see the NMS manual.

 

NOTE: The SNMP settings on the agent and the NMS must match.

 

3.       Verify the configuration:

# Try to get the count of sent traps from the agent. The get attempt succeeds.

Send request to 1.1.1.1/161 ...

Protocol version: SNMPv3

Operation: Get

Request binding:

1: 1.3.6.1.2.1.11.29.0

Response binding:

1: Oid=snmpOutTraps.0 Syntax=CNTR32 Value=18

Get finished

# Try to get the device name from the agent, but the get attempt fails because the NMS has no access right to the node.

Send request to 1.1.1.1/161 ...

Protocol version: SNMPv3

Operation: Get

Request binding:

1: 1.3.6.1.2.1.1.5.0

Response binding:

1: Oid=sysName.0 Syntax=noSuchObject Value=NULL

Get finished

# Execute the shutdown or undo shutdown command on an idle interface on the agent. You can see the interface state change traps on the NMS:

1.1.1.1/3374 V3 Trap = linkdown

SNMP Version = V3

Community = managev3user

Command = Trap

1.1.1.1/3374 V3 Trap = linkup

SNMP Version = V3

Community = managev3user

Command = Trap

SNMP logging configuration example

Network requirements

Configure the SNMP agent (1.1.1.1/24) in Figure 5 to log the SNMP operations performed by the NMS.

Figure 5 Network diagram

 

Configuration procedure

 

NOTE: This configuration example assumes that you have configured all required SNMP settings for the NMS and the agent (see ”SNMPv1/SNMPv2c configuration example” or “SNMPv3 configuration example”).

 

# Enable displaying log messages on the configuration terminal. (This function is enabled by default so that you can skip this step).

<Agent> terminal monitor

<Agent> terminal logging

# Enable the information center to output the system events of the informational or higher severity to the console port.

<Agent> system-view

[Agent] info-center source snmp channel console log level informational

# Enable logging GET and SET operations.

[Agent] snmp-agent log all

# Verify the configuration.

·           Use the NMS to get a MIB variable from the agent. The following is a sample log message displayed on the configuration terminal:

%Jan 1 02:49:40:566 2006 Sysname SNMP/6/GET:

seqNO = <10> srcIP = <1.1.1.2> op = <get> node = <sysName(1.3.6.1.2.1.1.5.0)> value=<>

·           Use the NMS to set a MIB variable on the agent. The following is a sample log message displayed on the configuration terminal:

%Jan 1 02:59:42:576 2006 Sysname SNMP/6/SET:

seqNO = <11> srcIP = <1.1.1.2> op = <set> errorIndex = <0> errorStatus =<noError> node = <sysName(1.3.6.1.2.1.1.5.0)> value = <Agent>

Table 1 Field description

Field	Description
Jan 1 02:49:40:566 2006	Time when the SNMP log is generated.
seqNO	Serial number automatically assigned to the SNMP log, starting from 0.
srcIP	IP address of the NMS.
op	SNMP operation type (GET or SET).
node	MIB node name and OID of the node instance.
erroIndex	Error index, with 0 meaning no error.
errorStatus	Error status, with noError meaning no error.
value	Value set when the SET operation is performed (this field is null for a GET operation). If the value is a character string that has characters beyond the ASCII range 0 to 127 or invisible characters, the string is displayed in hexadecimal format, for example, value = <81-43>[hex].

 

NOTE: The information center can output system event messages to several destinations, including the terminal and the log buffer. In this example, SNMP log messages are output to the terminal. To configure other message destinations, see the chapter “Configuring information center.”

 

Overview

MIBs fall into public MIBs and private MIBs. A private MIB is attached to a sub-node under the enterprises MIB node (1.3.6.1.4.1). The H3C private MIB has two styles: the H3C compatible MIB style and the H3C new MIB style.

·           In the H3C compatible MIB style, the device public MIB is under the H3C’s enterprise ID 25506, and the private MIB is under the enterprise ID 2011.

·           In the H3C new MIB style, both the device public MIB and the private MIB are under the H3C’s enterprise ID 25506.

These two styles of MIBs implement the same management function. Your device comes with a MIB loaded but the MIB style depends on the device model. You can change the MIB style as needed, but must make sure that the device is using the same MIB style as the NMS.

Setting the MIB style

To set the MIB style:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Set the MIB style.	mib-style [ new | compatible ]	By default, H3C new MIB style is used.

 

NOTE: After changing the MIB style, reboot the device to validate the change.

 

Displaying and maintaining MIB

 

Task	Command	Remarks
Display the MIB style.	display mib-style [ | { begin | exclude | include } regular-expression ]	Available in any view