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 after entering the ‘nms’ node or directly from Docker:

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

or

docker exec clab-cdc-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.