banshee/network-collection/network/cisco/snmp/ios/stack

Stack of Cisco Catalyst switches, by SNMP

Returns, for a stack of Cisco Catalyst switches (StackWise), the role and the state of each member, the number of members, and whether the stack cables close the ring. Four watches are offered: a member not ready, the ring broken, an unexpected number of members, and a member missing.

How it works

The collector reads cswSwitchInfoTable and cswRingRedundant (CISCO-STACKWISE-MIB).

A member is named by its switch number (switch 2), cswSwitchNumCurrent, the number on its front panel.
The role is cswSwitchRole in words: master (the active switch), standby, member, not-member.
The state is cswSwitchState in words: ready when the member works, otherwise waiting, progressing, added, sdm-mismatch, version-mismatch, feature-mismatch, new-master-init, provisioned, invalid, removed. "Member not ready" is critical when a member stays out of ready for 3 runs: a reload passes through the other states within that time.
The number of members counts the rows of the table, the provisioned ones included.
The ring is redundant when the stack cables close it, so that one cable more can be lost without splitting the stack; not-redundant otherwise, a cable cut or unplugged.
A switch that serves no stack table stops the collector as misconfigured.

The collector only reads: SNMP sends nothing but reads.

Prerequisites

The SNMP agent of the stack enabled, reachable from the poller (UDP 161), its access restricted to the poller.
The view granted to the poller includes ciscoStackWiseMIB (.1.3.6.1.4.1.9.9.500).
Read-only access, SNMPv2c or SNMPv3, set on the host or one of its folders (protocol:snmp:* variables).
Versions: IOS and IOS-XE on stackable Catalyst switches (3750, 3850, 9200, 9300 and their kin). It sits under ios/ because NX-OS has no StackWise.

Outputs

Name	Label	Unit	Per instance
`role`	Role	—	yes, per member
`state`	State	—	yes, per member
`members`	Members	—	no
`ring`	Stack ring	—	no

Watches

Name	Title	Kind	Defaults	Checked by default
`not-ready`	Member not ready	expected value, on `state`	critical when the state is not `ready`, for 3 runs	yes
`ring-broken`	Stack ring broken	state to avoid, on `ring`	warning on `not-redundant`	yes
`member-count`	Unexpected number of members	expected value, on `members`	no number given: it raises nothing until the number is set on the probe	no
`missing`	Missing member	expected instances, on `state`	no member named: it raises nothing until names are set on the probe	no

Limits

A stack of one switch has no ring: "Stack ring broken" then raises from the first run. Uncheck it on such a stack.
A member that dies may stay in the table as removed or provisioned, or leave it, depending on the version: "Member not ready" sees the first case, "Missing member" and "Unexpected number of members" the second. Which one a given version does is not verified here without a device.
The stack ports themselves (cswStackPortInfoTable) are not read: a cable cut shows in the ring.