Cisco Switch Troubleshooting Commands

Updated 3 weeks ago by Eric Hufford

Scope

Below are some useful commands that can be used to diagnose and troubleshoot Livewire problems within a Cisco switch.


Description

It is common for people to issue a "show running-config" command to determine whether a Cisco switch is programmed correctly for Livewire, but there are also several other useful commands that can show the status of IGMP querier, cpu load, spanning-tree status, and others.

These commands work on Cisco Catalyst switches, however depending on the model and version of IOS you are using, some commands could vary slightly. All commands should be entered in privileged mode (login and then type "enable")


IGMP (Multicast)

Check IGMP snooping

Diagnostic benefit:

Useful for checking multicast IP address groups and what ports subscribe to them

Command:

sh ip igmp snooping groups

Expected output format:

Vlan      Group                    Type        Version     Port List
-----------------------------------------------------------------------
1 224.0.1.129 igmp v2 Gi1/0/11, Gi1/0/19
1 238.38.38.38 igmp v2 Gi1/0/19
1 239.128.0.0 igmp v2 Gi1/0/7
1 239.128.0.251 igmp v2 Gi1/0/7
1 239.192.0.101 igmp v2 Gi1/0/19
1 239.192.1.245 igmp v2 Gi1/0/4
1 239.192.1.246 igmp v2 Gi1/0/4
1 239.192.4.1 igmp v2 Gi1/0/19
1 239.192.4.127 igmp v2 Gi1/0/14
1 239.192.6.171 igmp v2 Gi1/0/11
[output cut]

Show IGMP Group Count

Diagnostic benefit:

Shows how many IGMP groups are actively being queried on the switch. Useful for diagnosing if the number of active groups exceed the switch's capability.

Command:

sh ip igmp snooping groups count

Expected output:

Total number of multicast groups: 123

Check IGMP querier

Diagnostic benefit:

Determine the active querier on each vlan.

Command:

sh ip igmp snooping querier detail

Expected output:

Global IGMP switch querier status
--------------------------------------------------------
admin state : Enabled
admin version : 2
source IP address : 0.0.0.0
query-interval (sec) : 60
max-response-time (sec) : 25
querier-timeout (sec) : 205
tcn query count : 2
tcn query interval (sec) : 10

Vlan 1: IGMP switch querier status
--------------------------------------------------------
elected querier is 10.100.40.5 (this switch querier)
--------------------------------------------------------
admin state : Enabled
admin version : 2
source IP address : 10.100.40.5
query-interval (sec) : 60
max-response-time (sec) : 25
querier-timeout (sec) : 205
tcn query count : 2
tcn query interval (sec) : 10
operational state : Querier
operational version : 2
tcn query pending count : 0


Topology

Discover other Cisco switches connected to your switch

Diagnostic benefit:

Discover the Cisco switches that are connected to this switch, including what ports they are connected to.

Command:

sh cdp neighbors

Expected output:

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID Local Intrfce Holdtme Capability Platform Port ID
Switch Gig 1/0/23 175 S I WS-C2960- Gig 0/1

Show the connected switch's details

Diagnostic benefit:

Discover more details about the Cisco switches that are connected to this switch, including IP address, IOS, native VLAN, and others.

Command:

sh cdp neighbors detail

Expected output:

Device ID: Switch
Entry address(es):
IP address: 10.100.40.254
Platform: cisco WS-C2960-24TT-L, Capabilities: Switch IGMP
Interface: GigabitEthernet1/0/23, Port ID (outgoing port): GigabitEthernet0/1
Holdtime : 172 sec

Version :
Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 15.0(2)SE11, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2017 by Cisco Systems, Inc.
Compiled Sat 19-Aug-17 09:34 by prod_rel_team

advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010231FF000000000000002291282A00FF0000
VTP Management Domain: ''
Native VLAN: 1
Duplex: full
Management address(es):
IP address: 10.100.40.254

Spanning-Tree Protocol Status

Diagnostic benefit:

Show the status of STP on your switch per vlan, which switch is designated as the "root bridge," and what the status of each ports are.

Command:

sh spanning-tree 

Expected output:

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 1833.9d49.4c00
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 1833.9d49.4c00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/24 Desg FWD 4 128.24 P2p
[output cut]


Switch Environment

Show switch CPU utilization

Diagnostic benefit:

Understand if switch CPU is running at acceptable levels. Identifies processes that may be utilizing too much processing power.

Command:

sh processes cpu

Expected output:

CPU utilization for five seconds: 9%/0%; one minute: 10%; five minutes: 10%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
1 0 11 0 0.00% 0.00% 0.00% 0 Chunk Manager
2 0 510 0 0.00% 0.00% 0.00% 0 Load Meter
3 6 22 272 0.00% 0.00% 0.00% 0 DHCPD Timer
4 19828 1127 17593 0.00% 0.55% 0.65% 0 Check heaps
5 0 2 0 0.00% 0.00% 0.00% 0 Pool Manager
6 0 2 0 0.00% 0.00% 0.00% 0 Timers
7 0 1 0 0.00% 0.00% 0.00% 0 License Client N
8 4193 44 95295 0.00% 0.18% 0.13% 0 Licensing Auto U
9 0 1 0 0.00% 0.00% 0.00% 0 Image License br
[output cut]

Show switch CPU utilization (graph)

Diagnostic benefit:

Historical, graph version of the sh processes cpu command.

Command:

sh processes cpu history

Expected output:

                                                              
11 11111111111111111111
2299999999999999999999888888888899999000000000000000111117
100
90
80
70
60
50
40
30
20
10 **********************************************************
0....5....1....1....2....2....3....3....4....4....5....5....
0 5 0 5 0 5 0 5 0 5
CPU% per second (last 60 seconds)

11113111111111111111111111111111111111111111
52642654458335556545566444245555644556885548
100
90
80
70
60
50
40
30 *
20 * * *** ** ***** **** ***** ******* *
10 ############################################
0....5....1....1....2....2....3....3....4....4....5....5....
0 5 0 5 0 5 0 5 0 5
CPU% per minute (last 60 minutes)
* = maximum CPU% # = average CPU%



100
90
80
70
60
50
40
30
20
10
0....5....1....1....2....2....3....3....4....4....5....5....6....6....7.
0 5 0 5 0 5 0 5 0 5 0 5 0
CPU% per hour (last 72 hours)
* = maximum CPU% # = average CPU%

Show switch temperature and fan status

Diagnostic benefit:

Determine temperature and fan status of switch to check overheating.

Command:

sh env all

Expected output:

FAN is OK
TEMPERATURE is OK
Temperature Value: 25 Degree Celsius
Temperature State: GREEN
Yellow Threshold : 50 Degree Celsius
Red Threshold : 60 Degree Celsius
SW PID Serial# Status Sys Pwr PoE Pwr Watts
-- ------------------ ---------- --------------- ------- ------- -----
1 Built-in Good

SW Status RPS Name RPS Serial# RPS Port#
-- ------------- ---------------- ----------- ---------
1 <> <>


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