STP (Spanning Tree Protocol)
Spanning Tree Protocol (STP) prevents frame loops by putting interfaces on a switch into a forwarding or blocking states.
| Command | Description |
|---|---|
| (config)# spanning-tree vlan 1 root {primary, secondary} | Device the primary/secondary root bridge. |
| (config)# spanning-tree portfast bpduguard default | To Enable bpdu guard for all portfast enable interfaces |
| (config)# spanning-tree portfast default | To Enable portfast for all non-trunk interfaces |
| (config-if)# spanning-tree bpduguard enable | To Enable gpduguard on this interface |
| (config-if)# spanning-tree portfast | To Enable portfast on this interface |
| (config-if)# spanning-tree guard root | To Enable root guard on this interface |
Troubleshoot STP:
| Command |
|---|
| # show spanning-tree [vlan 1] |
| # show spanning-tree summary |
| # show running-config interface g1/1 |
| # show spanning-tree interface g1/1 portfast |
Etherchannel:
EtherChannel is a port link aggregation technology that groups multiple physical port links into one logical link. Used to provide high-speed connectivity and redundancy. Up to eight links can be aggregated into one logical link.
| Command | Description |
|---|---|
| (config)# interface range g1/1 – 2 | To configure g1/1 and g1/2 at the same time |
| (config-if-range)# channel-group 1 mode {auto, desirable} | To Add both interfaces to EtherChannel 1 (PAgP) |
| (config-if-range)# channel-group 1 mode {active, passive} | To Add both interfaces to EtherChannel 1 (LACP) |
| (config-if-range)# channel-group 1 mode on | To Add both interfaces to EtherChannel 1 (Static) |
| (config)# interface port-channel 1 | To Configure virtual interface for EtherChannel 1 |
| (config-if)# switchport mode trunk | To Put EtherChannel 1 in trunk mode |
| (config-if)# switchport trunk allowed vlan 10,20,30 | To Add tagged VLANs 10,20,30 on EtherChannel 1 |
Troubleshoot Etherchannel:
| Command | Description |
|---|---|
| # show interface port-channel 1 | Combined bandwidth and members as extra info. |
| # show etherchannel summary | To Show EtherChannel protocols and members as a list |
| # show etherchannel port-channel 1 | To Show per member state and stats |
CCNA Cheatsheet
A CCNA certification proves you have the competencies needed to navigate an ever-changing IT landscape. CCNA exams cover network fundamentals, IP services, security fundamentals, automation, and programmability. Designed for agility and versatility, CCNA proves you have the skills needed to manage and optimize today’s most advanced networks. CCNA training courses and exams are the foundation for advancing your career in any direction. A Cisco certification is living proof of the standards and rigor your organization recognizes and trusts to meet and exceed market demands. Here is a cheat sheet for CCNA Examination.