Check the operational state before changing a Cisco configuration. These references concentrate on IOS XE, with Catalyst switching and router-specific features clearly separated. They do not treat ASA, NX-OS or IOS XR as interchangeable command sets.
10 references
Read-only results link to an individual observation command. Other commands on the same page can have different effects.
No matching references. Try a task such as packet capture, route lookup, BGP or interface errors.
For a Layer 2 path, inspect the physical interface, access or trunk role, VLAN forwarding and spanning-tree state. Check EtherChannel membership before investigating a single member as an independent link. Use CDP or LLDP with ARP and MAC learning to locate a device through the topology.
For routed traffic, check the correct VRF and route, then compare forwarding information and the routing-protocol state. An established BGP neighbor or an OSPF adjacency does not prove that the destination prefix is available. ACL and NAT references help follow one connection without clearing counters or translations.
Examples use named ports, VLANs and addresses that you must replace. Read the platform notes when a field is missing: counters and hardware behavior vary by Catalyst model and software release. Each article explains the useful observation and the conclusion it does not justify.
Check Cisco IOS XE interface status, CRC errors, drops and err-disabled ports. Read-only Catalyst commands with a practical troubleshooting workflow.
Read-only command: show interfaces status
Troubleshoot Cisco Catalyst VLANs and 802.1Q trunks with read-only IOS XE commands. Compare allowed, active and forwarding VLANs at both ends.
Read-only command: show vlan brief
Find the STP root, inspect blocked ports and investigate inconsistent states on Cisco IOS XE. Includes separate PVST and MST read-only workflows.
Read-only command: show spanning-tree summary
Check Cisco IOS XE port-channel status, LACP neighbors and member flags. Understand suspended links and uneven traffic without resetting the bundle.
Read-only command: show etherchannel summary
Trace an IP address to a Cisco switch port using ARP, MAC tables, CDP and LLDP. Learn which table to check and where the method stops working.
Read-only command: show ip arp 192.0.2.10
Look up an IPv4 route in Cisco IOS XE, select the correct VRF and inspect CEF forwarding. Separate routing-table evidence from end-to-end reachability.
Read-only command: show ip route 203.0.113.25
Check IOS XE BGP sessions, accepted prefixes, advertised routes and route installation. Read-only commands with practical interpretation and scope limits.
Read-only command: show ip bgp summary
Troubleshoot OSPFv2 on IOS XE using neighbor, interface and database commands. Understand 2-Way, ExStart and Full without resetting the process.
Read-only command: show ip ospf
Check IOS XE IPv4 ACL attachment and rule matches. Learn why zero software counters on Catalyst 9000 do not prove that hardware traffic missed an ACL.
Read-only command: show ip interface GigabitEthernet0/0/0
Inspect IOS XE IPv4 NAT translations and statistics without clearing sessions. Follow a single flow and distinguish NAT state from successful connectivity.
Read-only command: show ip nat translations
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