Month: January 2019

ip v4
Networking

An introduction to IP version 4 (IPV4)

Internet Protocol (IP) addresses are the numbers that enable our computers, servers, telephones, cameras and printers communicate with each other. Based on the OSI model this logical address is added in the Network layer (layer 3). IP address is 32 bits long and divided into 4 parts. Each part has 8 bits which is called octet. […]

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Improve STP Convergence
Networking

How to improve STP convergence

Normally, STP needs at least 30 seconds for convergence (forward delay = Learning time + Forwarding time). In many environments, a 30 seconds outage for every topology change is unacceptable. Cisco developed three proprietary features that improve STP convergence time: PortFast UplinkFast BackboneFast Each feature will be covered in detail in the following section: PortFast […]

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STP security
Networking

Guidelines for securing STP

Before talking about the guidelines we need to take care of in order to secure STP protocol, let’s describe why protecting STP is important and what happens if an attacker changes the STP topology. Remember that: STP builds the topology by accepting BPDUs from neighboring switches. The Root Bridge is always determined by the lowest […]

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STP Timers
Networking

STP Timers and Topology Change Notifications

In this article, we are going to learn about STP Timers and the steps we need to follow in order to set them. Also, we’ll describe two types of BPDUs that switches exchange when building and converting the topology database. STP Timers Switches that run STP exchange BPDUs to build and converge the topology database. There […]

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spanning tree version
Networking

STP versions and Port states

Before starting to read this article, you need to know how STP protocol selects the Root Port and how Designated Ports are defined by STP.  This protocol has three versions and has faced many improvements over the past years. Common Spanning Tree (CST) Per-VLAN Spanning Tree (PVST) Per-VLAN Spanning Tree Plus (PVST+) Rapid Spanning Tree […]

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STP designated port selection
Networking

How STP selects Designated Ports

After the Root bridge is selected by STP protocol and after the switches have chosen their Root Port (RP), the third step is to identify the Designated port (DP). This port is responsible for forwarding BPDUs and frames. A single DP port is identified for each network segment. If two ports are eligible to become […]

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STP Root Bridge selection
Networking

How STP selects Root Bridge and Root Port

Selecting a Root Bridge in STP is the first step for the convergence to heppen inside a network. We explained in Introduction to STP Protocol that a Root Bridge is the central reference point for STP. You must keep in mind to choose the most powerful switch in the network as the STP Root Bridge. […]

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spanning tree protocol - introcuction
Networking

An introduction to Spanning Tree Protocol (STP)

Before describing the technical specs of the Spanning Tree Protocol (STP), you need to know how a layer 2 loop occurs when a client sends a broadcast data. As you may know, all ports of layer 2 switches belong to only one Broadcast Domain. So when a station sends broadcast traffic to the switch, the […]

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EtherChannel config
Networking

Etherchannel or Interface Binding

An EtherChannel or interface binding is aggregating multiple physical interfaces to a single logical link in order to increase bandwidth up to eight physical links. You can build an EtherChannel by setting up to eight compatibly configured LAN ports. All LAN ports in each EtherChannel must have the same speed and must all be configured as either […]

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virtual trunking protocol
Networking

What is Virtual Trunking Protocol (VTP)

In order to fulfill many different goals in a growing network, we need to configure multiple VLANs. For instance, in a network with 36 switches, you might need to configure 10 independent VLANs on each of these switches. This means you are gong to need to configure a total of 360 VLANs! Virtual Trunking Protocol (VTP) […]

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