Cisco Switch Troubleshooting Commands
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.
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#
-- ------------- ---------------- ----------- ---------
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