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Articles:
The OSI Model: Layer 5 - Session Layer
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The OSI Model: Layer 4 - Transport Layer
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The OSI Model: Layer 3 - Network Layer
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The OSI Model: Layer 2 - Datalink Layer
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The OSI Model: Layer 1 - Physical Layer
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Suggested Articles:
Ethernet Protocol, CSMA/CD, Collisions
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ICMP Protocol
ICMP Protocol - Part 6: Redirect Messages
The ICMP - Redirect Message is always sent from a gateway to the host and the example below will illustrate when this is used.
Putting it simply (be…
Domain Name System (DNS)
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This section will help you understand how the DNS queries work on the Internet and your home network. There are two ways to use the domain name syste…
Network Address Translation - NAT
Dynamic NAT - Part 2
Our previous article, Dynamic NAT - Part 1, covered the basic idea of Dynamic Network Address Translation. We are now going to take a closer look at…
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Netflow Articles:
Netflow: Monitor Bandwidth & Network Utilization…
Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, applic…
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SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ne…
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VLAN Networks
VTP Introduction & Modes
The invention of VLANs was very much welcomed by all engineers and administrators, allowing them to extend, redesign and segment their existing network wi…
VLAN Networks
Static VLANs
VLANs are usually created by the network administrator, assigning each port of every switch to a VLAN. Depending on the network infrastructure and securit…
VLAN Networks
VTP Pruning
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VLAN Networks
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We mentioned that Trunk Links are designed to pass frames (packets) from all VLANs, allowing us to connect multiple switches together and independently co…
Routing
Interior Gateway Protocol - IGRP
IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance-vector routing protocol used in enterprise networks to exchange routing informati…
Routing
OSPF - Part 5: Analysis of OSPF Link State Update (LSU…
This article explains how OSPF uses Link State Advertisement (LSA) to exchange information about the network topology between routers. When a router recei…
Routing
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Open Shortest Path First (OSPF) is a popular routing protocol developed for Internet Protocol (IP) networks by the Interior Gateway Protocol (IGP) working…
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Configuring Dynamic NAT (NAT Overload) On A Cisco Rout…
NAT (Network Address Translation) is a method that allows the translation (modification) of IP addresses while packets/datagrams are traversing the networ…
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How to Install and Configure SNMP for Windows Server 2…
Simple Network Management Protocol (SNMP) is a UDP protocol that uses port 161 to monitor and collect detailed information on any network device supportin…
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Cisco Catalyst 4500 Series Zero-Downtime IOS Upgrade P…
The Supervisor Engine is the heart of the Cisco Catalyst 4500 and 6500 series switches. It is the equivalent of an engine in a car. Every packet that ente…
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Palo Alto Firewall Application-based Policy Enforcemen…
Our previous article examined the benefits of Palo Alto Networks Firewall Single Pass Parallel Processing (SP3) architecture and how its combine with the…







