Cisco IOU Unsupported Features

Here is a list of Cisco IOU unsupported features that you probably won’t find, when labbing using Eve-NG or GNS3. The missing features were found with i86bi-linux-l2-adventerprise-15.1b.bin image. But the same observations could be true for other versions too. Cisco IOU ... Read More »

Spanning Tree Root Port Election

Spanning Tree Root Port Election: How does it work? We said that non-tooy ridges have one Root Port. But how is it chosen? The Root Port is elected by the following criteria: the port that receives the superior BPDU the ... Read More »

Spanning Tree Operation

We explore the operations of the Spanning Tree Protocol. Spanning Tree operation: how the protocol works Here is a topology we’re going to work with: The Root bridge elections start. Switches exchange Ethernet BPDU frames. The BPDUs are Configuration BPDUs. ... Read More »

Spanning Tree BPDU Format

Let’s explore the Spanning Tree Protocol BPDU format. Bridges exchange BPDUs encapsulated into Ethernet frames. There are two types of BPDUs: Configuration BPDU TCN BPDU Spanning Tree BPDU format : what does it look like in an Ethernet Frame? Let’s ... Read More »

Spanning Tree BPDU Filter Notes

There are two seperate ways to configure it: – globally: (config)#spanning-tree portfast bpdufilter default + enables BPDU filter on all portfast interfaces + kicks them out of portfast if they receive a BPDU – per portfast interface: (config-if)#spanning-tree bpdufilter enable ... Read More »

Full Duplex Issue on IOL


Trying to configure duplex settings under an IOL switch interface can be a pain in the ass, especially when you are practicing RSTP and you need to have point-to-point links. You do “show spanning-tree” and you see that your interfaces ... Read More »

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