SNMP Tools

This section demonstration of the use of SNMP tools to get information from the routers. The SNMP tools implement the messages: ‘getRequest’, ‘getNextRequest’, and ‘getBulkRequest’.

Before you start, make sure that topology is deployed and SNMP is enabled on all routers before proceeding.

$ ./utils/enable_snmp.sh
...
$ ./utils/test_snmp.sh
...

You should not get any errors after executing the above commands.

Notes:

• You can limit the topology to the routers and the management workstation only:

   sudo clab deploy -t cvx-dcn.clab.yaml --node-filter spine01,spine02,leaf01,leaf02,leaf03,nms
  

• All the examples use ‘spine01’ as target but you can change the address to any other router.

The following commands can be executed from the host machine:

$ snmpwalk -v 2c -c snmpcumulus 172.20.20.11 system

or from the ‘nms’ node (if snmp tools are not installed on the host machine):

$ docker exec clab-cdc-nms snmpwalk -v 2c -c snmpcumulus 172.20.20.11 system

You can also enter the ‘nms/ node:

docker exec -it clab-cdc-nms bash
nms:~# snmpwalk -v 2c -c snmpcumulus 172.20.20.11 system

getRequest

snmpget -v 2c -c snmpcumulus 172.20.20.11 sysName.0
snmpget -v 2c -c snmpcumulus 172.20.20.11 sysUpTime.0

Add the option ‘-On’ to print the numeric value of the OID.

getNextRequest

snmpgetnext -v 2c -c snmpcumulus 172.20.20.11 system
snmpgetnext -v 2c -c snmpcumulus 172.20.20.11 sysDescr.0

getBulkRequest.

The last paramter r3 represent the number of number of OIDs requested

snmpbulkget -v 2c -c snmpcumulus -C n0 -C r3 172.20.20.11 system

This example explains the use of non-repeaters and max-repititions

snmpbulkget -v 2c -c snmpcumulus 172.20.20.11 system tcp ifTable -C n2 -C r5

Notice what happens when the non-repeaters changes

snmpbulkget -v 2c -c snmpcumulus 172.20.20.11 system tcp ifTable -C n1 -C r5

snmpwalk

snmpwalk retrieves the whole MIB tree or one MIB group using a series of ‘getNextRequest’ messages:

snmpwalk -v 2c -c snmpcumulus 172.20.20.11

snmpwalk -v 2c -c snmpcumulus 172.20.20.11 system

snmptable

To display a table:

snmptable -v 2c -c snmpcumulus -Os -Cw 90 172.20.20.11 ifTable

The -Cw 90 partitions the table to a maximum width of 90 characters.