Cisco Ios Patterns

---
name: cisco-ios-patterns
description: "Use when cisco IOS and IOS-XE review patterns for show commands, config hierarchy, wildcard masks, ACL placement, interface hygiene, and safe change-window verification. Triggers on \"cisco-ios-patterns\", \"cisco ios patterns\", \"patterns\"."
metadata:
  origin: community
---

# Cisco IOS Patterns

Use this skill when reviewing Cisco IOS or IOS-XE snippets, building a
change-window checklist, or explaining how to collect evidence from a router or
switch without making the incident worse.

## When to Use

- Reviewing IOS or IOS-XE configuration before a planned change.
- Choosing read-only `show` commands for troubleshooting.
- Checking ACL wildcard masks and interface direction.
- Explaining global, interface, routing process, and line configuration modes.
- Verifying that a change landed in running config and was saved intentionally.

## Operating Rules

Treat IOS examples as patterns, not paste-ready production changes. Confirm the
platform, interface names, current config, rollback path, and out-of-band access
before making changes on a real device.

Prefer this workflow:

1. Capture current state with read-only commands.
2. Review the exact candidate config.
3. Confirm management access cannot be locked out.
4. Apply the smallest change in a maintenance window.
5. Re-read state, compare to the baseline, then save only after validation.

## Mode Reference

```text
Router> enable
Router# show running-config
Router# configure terminal
Router(config)# interface GigabitEthernet0/1
Router(config-if)# description UPLINK-TO-CORE
Router(config-if)# no shutdown
Router(config-if)# exit
Router(config)# end
Router# show running-config interface GigabitEthernet0/1
```

`running-config` is active memory. `startup-config` is what survives reload.
Do not save a change just because a command was accepted; validate behavior
first, then use `copy running-config startup-config` if the change is approved.

## Read-Only Collection

```text
show version
show inventory
show processes cpu sorted
show memory statistics
show logging
show running-config | section line vty
show running-config | section interface
show running-config | section router bgp
show ip interface brief