Category Archives: Switches

Exploring vPCs and their verification

Virtual Port Channels (vPCs) allow you to ether channel or bundle multiple ports to the different devices.  Since the 7k/5k devices are looked at as one big virtual device, you can now use ether channel or load balancing and redundancy between multiple Nexus switches. vPC Peers are the bundled devices that act as one single… Read More »

Using ACLs in NX-OS

As usual, the same guidelines apply: You need at least one permit since there is always an implicit deny. The order matters. The global lists are first created then need to be assigned to a purpose. They will either recognize traffic and let it serve the purpose or prevent it from serving its purpose. One… Read More »

NX-OS – Layer 2 Redudancy

Layer 2 redundancy protocols exist to prevent loops from broadcasts and do so using BPDU packets.  These protocols include: STP – Spanning Tree Protocol – 802.1D RSTP – Rapid Spanning Tree Protocol – 802.1W MSTP – Multiple Spanning Tree Protocol  – 802.1S LAN Port Channeling – Also known as EtherChannels to bind multiple ports together.… Read More »

Using NX-OS for beginners

To show all commands in your buffer history: show cli history This command used to be show history on the old OS. Some enhanced editing shortcuts include: Ctrl+A – to get to the beginning of the line Ctrl+E – to get to the end of the line Ctrl+B – moves one character to the left… Read More »

Cisco Switches – Troubleshooting and Security

1) Get familiar with the network 2) Create an accurate Network Diagram! 3) Work logically, from the bottom up in the OSI model: Physical > Data Link > Network > Transport > Session > Presentation > Application Most problems lie within Physical, Data Link, Network, and Transport. The issues above that are usually based around… Read More »

Configuring Spanning Tree Protocol (STP)

Spanning Tree protocol works with networks where you have multiple switches all plugging into more switches and you need redundancy.  It allows you to have primary and secondary backup switches.  Most large networks have their layered approach with core switches, distribution switches, and access switches which could be very bad without STP. The key to… Read More »

Configuring VLANs and VTP

To configure a trunk port: conf t interface fastEthernet 0/24 switchport mode trunk OR switchport trunk encapsulation dot1q switchport mode trunk To configure all other ports as access ports: conf interface range fastEthernet 0/1 – 0/23 switchport mode access show vtp status – shows everything you need to know about VTP.  In particular the revisions… Read More »