Network infrastructure
Network hardware and physical appliances, such as routers, switches, gateways, hubs and bridges, serve as the vital foundation of network infrastructure. Common network protocols and more emergent network software also play major roles in any architecture. While networking has shifted to software-centric principles, see how traditional network infrastructure keeps pace.
Top Stories
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Answer
23 Jul 2024
MAC address vs. IP address: What's the difference?
A MAC address and an IP address each identify network devices, but they do the jobs at different levels. Explore the differences between the two and learn why both are necessary. Continue Reading
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Feature
18 Jul 2024
Broadband equity initiatives bridge digital divide in K-12
Federally funded broadband programs support infrastructure upgrades to underserved communities, which address the digital divide in K-12 education. Continue Reading
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Opinion
18 Apr 2014
Identify this network convergence nomenclature: You could be a winner
As the admin and platform owner of a project, Patrick Hubbard has to monitor everything, and he coined a new term that describes that responsibility. Continue Reading
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Tip
06 Feb 2014
Hyper-V networking: The three virtual switches that fuel connectivity
In this Hyper-V networking primer, learn about the three virtual switches behind Microsoft virtualization connectivity. Continue Reading
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Answer
12 Nov 2013
Subnet basics: Must you set up Wi-Fi subnets in a single building?
Expert Mike Jude discusses the rationale of creating distinct Wi-Fi subnets in a single building. Continue Reading
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Answer
29 Aug 2013
Are there alternatives to the OpenFlow protocol?
Jason Edelman explains OpenFlow protocol alternatives and what's important in determining which southbound protocol will work for you. Continue Reading
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Definition
26 Jun 2013
compatibility
In the world of IT, compatibility refers to the ability of software and hardware from different sources to work together without having to be altered to do so. Continue Reading
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News
13 Jun 2013
News briefs: Red Hat OpenShift Online goes live; Lenovo pushes cloud
This week, Red Hat's OpenShift Online rolls out for commercial use, Lenovo enters the cloud market and NTT deploys VMware network virtualization. Continue Reading
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Feature
03 Jun 2013
What is Ethernet-dedicated Internet?
Ethernet-dedicated Internet is a continuous, high-bandwidth way for enterprises to connect their LANs to the public Internet and to streamline the performance of their WAN. Continue Reading
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News
06 May 2013
Interop Conference 2013
Your home for all the news at Interop Conference 2013. Cloud computing, SDN, big data, virtualization, data center networking and more from New York City. Continue Reading
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Feature
29 Apr 2013
Primer: A new generation of programmable ASICs
Programmable application-specific integrated circuits allow the data plane of switches to support new technologies, like software-defined networking. Continue Reading
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Feature
18 Mar 2013
How to plan for a campus core switch refresh: Basic requirements
Network architects and engineers discuss the features and functions they look for when planning a campus core upgrade. Continue Reading
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Tip
12 Mar 2013
Centralized vs. decentralized SDN architecture: Which works for you?
Two SDN architecture models -- centralized and decentralized -- have much in common, but key differences center on the use of the OpenFlow protocol. Continue Reading
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Definition
06 Mar 2013
NVGRE (Network Virtualization using Generic Routing Encapsulation)
NVGRE (Network Virtualization using Generic Routing Encapsulation) is a network virtualization method that uses encapsulation to create large numbers of virtual LANs (VLANs) for subnets that can extend across dispersed data centers and Layers 2 and 3. Continue Reading
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Feature
03 Jan 2013
Networking 2012: Top ten news stories of the year
The top ten networking news stories of 2012 reflect the tectonic shift in network technology, including software-defined networking and BYOD Wi-Fi. Continue Reading
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Photo Story
19 Dec 2012
Networking 2012: Top ten news stories of the year
The top ten networking news stories of 2012 reflect the tectonic shift in network technology, including software-defined networking and BYOD Wi-Fi. Continue Reading
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Feature
29 Nov 2012
Will we ever need 400 Gigabit Ethernet enterprise networks?
With 40 and 100 Gigabit Ethernet so new, what could possibly drive the need for 400 Gigabit Ethernet in the enterprise? Hint: It’s not just the WAN. Continue Reading
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Report
18 May 2012
Interop 2012: Conference Coverage recap
Check out our news, views and video from Interop 2012 in Las Vegas, which covered new service offerings, product announcements and networking trends. Continue Reading
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Answer
07 Jun 2011
Multiple access point configuration: Distinguish transmitted signals
Lisa Phifer explains multiple access point configuration when a device tries to differentiate transmitted signals from each point and explains potential issues. Continue Reading
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Definition
26 Oct 2010
fiber to the x (FTTx)
Fiber to the x (FTTx) is a collective term for various optical fiber delivery topologies that are categorized according to where the fiber terminates Continue Reading
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News
14 Oct 2010
Advanced wireless M2M services monetize machine-to-machine ecosystem
Many wireless M2M applications consume little bandwidth, translating to low ARPU. In response, carriers are launching concierge-style wireless M2M services to generate more revenue and widen partnerships within the larger M2M ecosystem. Continue Reading
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Tip
17 Aug 2010
Using virtual appliances and desktop virtualization
IT organizations are implementing desktop virtualization and virtual appliances for virtual WAN optimization and virtual application delivery, but there are challenges to overcome along the way. Continue Reading
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Feature
18 Dec 2009
Avaya-Nortel acquisition: Infamous end; questionable beginning
The Avaya-Nortel acquisition was one of the more notable top networking stories of 2009, marking the end of a legacy player and a questionable beginning for Avaya as it struggles with whether to integrate the Nortel data networking portfolio. Continue Reading
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Answer
04 Feb 2009
Difference between circuit-switching and packet-switching in examples
What is the difference between a circuit switching and packet switching? Our networking fundamentals expert gives examples of packet switching and circuit switching in this response. Continue Reading
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Answer
11 Dec 2008
Calculating subnets for IP addresses in IPv6
Understand how subnetting in IPv6 differs from that of IPv4 and what you need to do in order to calculate the subnet of an IP address in IP version 6. Continue Reading
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Feature
16 Sep 2008
Network-to-network VPN gateway configuration for Cisco EzVPN
Learn how to support network-to-network IPsec VPN topologies using a router as the VPN gateway with Cisco EzVPN. Continue Reading
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Definition
23 Apr 2008
NIS (Network Information System)
NIS (Network Information System) is a network naming and administration system for smaller networks that was developed by Sun Microsystems. Continue Reading
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Definition
31 Jul 2007
ROADM (reconfigurable optical add-drop multiplexer)
An ROADM (reconfigurable optical add-drop multiplexer) is a device that can add, block, pass or redirect modulated infrared (IR) and visible light beams of various wavelengths in a fiber optic network. ... (Continued) Continue Reading
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Tip
18 Jul 2007
Optical networks: Core network design best practices
Core optical network design must take into consideration network requirements specific to the core, including a high degree of aggregation, low reconfigurability, and large geographic scope, while confronting such challenges as router adjacency, service interconnection and overall management. Continue Reading
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Answer
20 Apr 2007
What equipment do I use to connect two LANs in different cities? What are the steps?
How do you connect two LANS from different cities? VPN expert Sampath Ramaswami notes the steps to be taken, in this Q&A. Continue Reading
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Tip
22 Feb 2007
Cisco wireless access point configuration from scratch
Learn what the Cisco 1242 wireless access point can do for you and how to configure one from scratch. This tip covers basic security settings, enabling the wireless radios, and how to make a successful connection. The 1242AG is a powerful business-grade wireless AP with lots of features. Continue Reading
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Tip
14 Dec 2006
Cisco WLAN design best practices
Wireless LAN (WLAN) technology has built-in security features, but a one-size-fits-all approach won't ensure adequate security for your organization. This tip provides best practices for designing your security architecture, including user community considerations, controller architecture and access point placement. Examples are specific to the Cisco Unified WLAN solution, but best practices apply for any WLAN deployment. Continue Reading
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Answer
04 Dec 2006
What is the relationship between network cable frequency and its bandwidth?
Learn about the relationship between the network cable's frequency and its bandwidth capacity, the frequency formula and its physics in this expert response by Carrie Higbie. Continue Reading
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Tip
29 Nov 2006
MPLS load sharing and high availability, Part 2: IP routing
MPLS has become a trusted transport option for convergent networks that require guaranteed levels of service, but successful implementation can require increased levels of redundancy to support failover. Robbie Harrell discusses how to enable high availability and load sharing utilizing MPLS transport. Continue Reading
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Tip
27 Nov 2006
LAN administration guide
LAN administration is an arduous task and your responsibilities often involve many different aspects and may include many tasks. This guide will help you with each step and task. Continue Reading
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Answer
25 Nov 2006
Half duplex vs. full duplex Ethernet 10BASE-T topologies
Ever wonder why half duplex Ethernet 10BASE-T topologies have a slower data transmission rate than full duplex Ethernet 10BASE-Ttopologies? Find out in this expert response by Lindi Horton. Continue Reading
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Answer
25 Nov 2006
What download speed will I get with a bandwidth of 1 MBPS?
Wondering what kind of download speed you can get with a bandwidth of 1 MBPS? Our expert, Lindi Horton can give you the lowdown on the download. Continue Reading
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Answer
25 Nov 2006
What are the fundamental principles of CDMA?
In this Q&A, our expert, Lindi Horton gives us an explanation of what CDMA is and what some of its fundamental principles are. Continue Reading
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Feature
22 Nov 2006
How a Switch Works -- Chapter 6 of 'LAN Switching First-Step'
How a Switch Works explains how to differentiate among unicast, multicast, and broadcast transmission methods; store-and-forward, cut-through, and fragment-free switching mechanisms and then describes Layer 2 and Layer 3 switching operation. Continue Reading
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Feature
22 Nov 2006
Introduction -- Chapter 1 of 'Network Analysis, Architecture and Design'
This chapter introduces the analysis, architecture, and design processes. Described are the fundamental concepts of the processes of network analysis, architecture, and design; systems and services; as well as their characteristics and prepares the reader for the analysis process. Continue Reading
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Tip
20 Nov 2006
IP addressing and subnetting: Calculate a subnet mask using the subnet's formula
IP addressing and subnetting are an important part of networks. Learn how the subnet's formula works and why it's important to know how to calculate the subnet mask "longhand." Continue Reading
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Tip
30 Oct 2006
Network test plan: Checklist for architecture changes
For every change you make to your network architecture, you should have a test plan and a backout plan. In this tip, learn how to build a test plan and review a sample checklist of things to include. Continue Reading
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Feature
25 Oct 2006
Mobility -- Chapter 5 of 802.11 Wireless LAN Fundamentals
Mobility, Chapter 5 of 802.11 Wireless LAN Fundamentals, covers the characteristics of roaming, Layer 2 roaming, Layer 3 roaming and an introduction to mobile IP. Continue Reading
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Tip
17 Oct 2006
Router Expert: Building a WLAN proxy server, DHCP services: Part 1
Router expert Michael Martin discusses DHCP implementation options and provides sample configurations to support various SSID network models in this continuation of his series on building a WLAN proxy server. Continue Reading
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Answer
04 Oct 2006
The most commonly used network operating system
In this Q&A, Lindi Horton answers the question "What network operating system is more currently and commonly used?" Continue Reading
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Tip
02 Oct 2006
OSI: Securing the stack, Layer 2 -- Understanding the role of ARP
Security expert Michael Gregg continues his layer-by-layer discussion of OSI model network security with this tip on the vulnerabilities present in Layer 2, the Data Link Layer, and specifically addresses the Address Resolution Protocol. Continue Reading
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Definition
05 Sep 2006
maximum segment size (MSS)
The maximum segment size (MSS) is the largest amount of data, specified in bytes, that a computer or communications device can handle in a single, unfragmented piece. Continue Reading
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Tip
04 Sep 2006
OSI: Securing the stack, Layer 1 -- Physical security threats
Security expert Michael Gregg kicks off his layer-by-layer discussion of OSI model network security with this tip on securing Layer 1 against physical security threats. Continue Reading
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Tip
28 Aug 2006
Duplex mismatch
What is duplex, and what is the difference between half and full duplex? What is a duplex mismatch? How can autonegotiation help or hurt your network? How can you resolve duplex conflicts? In this tip, David Davis helps networking engineers and newcomers understand the issues behind one of the most troublesome problems plaguing today's networks. Continue Reading
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Answer
20 Aug 2006
Wireless LAN setup for hotels
Phifer discusses the requirements for WLAN setups in hotels. Continue Reading
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Definition
07 Aug 2006
Kbps (kilobits per second)
In the U.S., Kbps stands for kilobits per second (thousands of bits per second) and is a measure of bandwidth (the amount of data that can flow in a given time) on a data transmission medium. Continue Reading
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Tip
28 Jul 2006
Troubleshooting wireless networks: A systematic approach
Troubleshooting wireless networks can take up a lot of time for network operations staff with a wireless LAN (WLAN) environment. Wireless guru Lisa Phifer discusses the tools and processes involved and breaks down how to approach and resolve wireless problems with a step-by-step, systematic method. Continue Reading
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Tip
21 Jul 2006
DNS for a wireless network: Router Expert
DNS services are essential for building a secure wireless LAN. Our Router Expert provides complete instructions for setting up a DNS server, including implementing BIND, configuring a non-authoritative server and creating zone files. Continue Reading
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Tip
22 Jun 2006
Security and the TCP/IP stack
Each layer of TCP/IP has security mechanisms, protocols, and applications. This tip describes the more popular ones that are associated with each layer of TCP/IP. Continue Reading
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Feature
16 Jun 2006
Wi-Fi firewalls boost wireless security by blocking airborne attacks
Wi-Fi firewalls, or wireless intrusion prevention systems, are servers that monitor and filter Wi-Fi traffic, blocking unauthorized 802.11 usage and attacks while still in the air. Learn about the benefits of the product and what to consider when selecting one. Continue Reading
- Answer 05 Jun 2006
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Quiz
29 May 2006
Wireless networking (CWNA)
Do you think you know a lot about wireless networking? Are you interested in taking the Certified Wireless Network Administrator (CWNA) exam? Test your knowledge with our 13-question quiz on wireless networking! Continue Reading
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Tip
17 May 2006
IEEE 802.3at: Power over Ethernet plus
802.3af Power over Ethernet (PoE) has been widely adopted for powering VoIP phones, wireless access points and a number of other network-connected products. But it provides a limited amount of power. In this tip, David Jacobs investigates the latest developments in 802.3at PoE, designed to deliver more power to each device. Continue Reading
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Tip
03 May 2006
Content Delivery Networking: an introduction
Doug Downer gives an overview of Content Delivery Network (CDN) technology and its components, which bring together the functionality of file access, caching, multimedia delivery and application processing. Continue Reading
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Answer
24 Apr 2006
Why is the cable supporting my LAN experiencing abnormal attenuation?
Why is the cable supporting my LAN experiencing abnormal attenuation? Continue Reading
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Tip
24 Apr 2006
Configuring and troubleshooting wireless LAN clients
An understanding of wireless LAN (WLAN) client and WLAN access point communication mechanisms is critical to anyone attempting to initially connect or troubleshoot a WLAN connection. In this tip, Robbie Harrell discusses some of the issues that can be dealt with on the client side when a user experiences WLAN connectivity problems. Continue Reading
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Feature
10 Apr 2006
Lesson 4: How to use wireless IDS/IPS
In Lesson 4 of Wireless Security Lunchtime Learning, you'll walk away with an understanding of the value of wireless IDS/IPS -- even if your organization doesn't support a wireless LAN. Also learn how to choose a WIDS for your environment and how to fight wireless DoS attacks. Continue Reading
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Feature
10 Apr 2006
Lesson 2: How to build a secure wireless infrastructure
In Lesson 2 of Wireless Security Lunchtime Learning, you'll learn how to build a secure wireless infrastructure by understanding the myriad security standards and features that Wi-Fi products boast, as well as how traditional wired network devices and configurations can be applied to a WLAN. Continue Reading
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Feature
10 Apr 2006
Using your WIDS to monitor WLAN performance
"Wireless intrusion detection" -- the very name brings to mind security. But many WIDS products can also be used to monitor WLAN performance, providing valuable insight for trouble-shooting, fine-tuning, and usage planning. This tip explains how to leverage your WIDS get more from your WLAN. Continue Reading
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Feature
10 Apr 2006
Wi-Fi vulnerability assessment checklist
Vulnerability assessments can help you find and fix WLAN weaknesses before attackers take advantage of them. But where do you start? What should you look for? Have you covered all the bases? This checklist will help to answer these questions. Continue Reading
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Feature
10 Apr 2006
Using VLANs to compartmentalize WLAN traffic
Virtual LANs have long been used within enterprise networks to create logical workgroups, independent of physical location or LAN topology. This tip describes how to use these same VLAN capabilities, found in both wired and wireless devices, to tag and compartmentalize Wi-Fi traffic, supporting your company's security and traffic management policies. Continue Reading
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Feature
10 Apr 2006
Combining 802.1X and VLANs for WLAN authorization
Many WLAN owners know that 802.1X/EAP makes it possible to authenticate individual wireless users. But did you know that 802.1X can also be used to funnel wireless traffic onto VLANs, enforcing user or group-based permissions? This tip explains how to use RADIUS attributes returned by 802.1X to supply VLAN tags, establishing that critical link between authentication and authorization. Continue Reading
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Feature
05 Apr 2006
Building a wireless LAN proxy server
Our router expert, Michael Martin, walks you through building an http proxy server for a wireless LAN with a Linux base. Continue Reading
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Tip
03 Apr 2006
Securing your Layer 2 network: Don't overlook the basics
Before dropping substantial cash on a fancy surveillance system, most sensible home owners would ensure that their doors and windows were locked. Similarly, there are simple security measures you can take to configure your systems for Layer 2 security. Continue Reading
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Tip
13 Feb 2006
IP network design, part 4: LAN design
This final section of the IP network design series relates to the issues encountered with campus LAN design. The benefits of Ethernet switching over a traditional hub environment are first explained. The motivation behind the deployment of virtual LANs (VLANs) is explored along with the issues faced when planning and configuring VLANs. This article also discusses techniques for ensuring a scalable and resilient campus network design. The Spanning Tree Protocol is also addressed and how it can be optimized on a large switched network. Finally, the design issues associated with an IP telephony rollout are covered in the conclusion of this article. Continue Reading
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Tip
01 Feb 2006
Implementing software restriction policies
This tip explains how you can use software restriction policies to keep your workstations in pristine shape and cut down on help desk calls at the same time. Continue Reading
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Tip
31 Jan 2006
Router Expert: Initial configuration of a Cisco 1200 802.11g WLAN access point
Our router expert continues his series on building a secure wireless LAN with a Linux base. This article explains how to utilize a single Cisco 1200 series access point to provide access to three different IP network segments using VLANs and multiple service set identifiers. Continue Reading
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Tip
31 Jan 2006
LAN connectivity problem: Blame DNS, NIC or firewall?
ITKnowledge Exchange member "BinooDas1234" had connectivity issues with a troublesome LAN, and fellow techies jumped in to help out. But does the answer lie in the DNS configuration, the NIC drivers or elsewhere? Here is a portion of the conversation. Continue Reading
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Definition
27 Jan 2006
home server
A home server is a computer that functions as a server in a client-server home network. Continue Reading
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Tip
27 Jan 2006
IP network design, part 2: The IP addressing plan
The IP addressing plan is the foundation upon which a successful logical design is built. Part two of this tip explains how to formulate a scalable IP addressing plan that can support the network as it grows. Continue Reading
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Tip
19 Jan 2006
IP network design, part 1: Fundamental principles
A competent network design is the foundation upon which all successful network implementations are built. This is the first of four articles that focus on the design of IP-based networks, due to the prevalence of IP as the de-facto standard desktop protocol. Continue Reading
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Tutorial
01 Jan 2006
802.11 Learning Guide
802.11 is perhaps the fastest-changing network protocol around. We've gathered a wealth of information to get you up-to-speed quickly on the various specifications. Learn about all the 802.11 wireless LAN (WLAN) specifications in this learning guide. Continue Reading
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Tip
09 Dec 2005
Making sense of Windows routing tables
When routing packets across a network, things do occasionally go wrong. In these situations, it is helpful to be familiar with the Windows routing tables. Routing tables dictate the flow of packets from the machine in question. This tip will show you how to view the Windows routing tables and how to make sense of the data that is contained within it. Continue Reading
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Tip
29 Nov 2005
Router numbers
Many of the routing protocols implemented in Cisco's IOS require a number to follow the command that enables the routing protocol in question. If you're new to routing, these numbers can be a little confusing, as they mean something different to each protocol. This tip presents a quick explanation and general guidelines for understanding router numbers. Continue Reading
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Tip
16 Nov 2005
Wireless LAN security: 802.11i
What is 802.11i, and is it really practical for you to implement in your organization? Robbie Harrell explores how the new wireless standard can improve security -- and reasons why you may want to switch to 802.11i or stick with WPA. Continue Reading
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Tip
10 Nov 2005
Router Expert: Building VLAN interfaces in Linux and IOS
Segmenting a wireless LAN with VLANs can increase security. Find out from our router expert how to support VLAN interfaces in Linux and Cisco IOS. Continue Reading
- Answer 07 Nov 2005
- Answer 26 Oct 2005
- Answer 14 Oct 2005
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Quiz
13 Oct 2005
Wireless LAN quiz
Take our wireless LAN quiz to find out how much you know about WLAN technologies. Continue Reading
- Quiz 13 Oct 2005
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Tip
13 Oct 2005
Router Expert: Building 802.11Q VLANs
Network segmentation can be a great way to increase security. This article covers segmenting with VLANs and the 802.1Q standard. Continue Reading
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News
10 Oct 2005
Analysts: 3Com trying to woo enterprises with new ad campaign
Following strategic missteps and profitability woes, 3Com hopes a new ad campaign will remind enterprises that Cisco and HP ProCurve aren't the only vendors in town. Continue Reading
- Answer 04 Oct 2005
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Tip
27 Sep 2005
The network administrator's guide to forensic first response
The time between discovery of an incident and the handover of digital evidence is critical for the possibility of successful evidence retrieval. Mishandled evidence, whether to be used in court or solely in house, can damage the integrity of the investigation. The most critical concern, then, is to create the most conducive environment possible for the forensic examiner. This tip will discuss vital considerations for the administrator acting in a first responder's role to maintain the integrity of evidence and accountability. Continue Reading
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Definition
21 Sep 2005
connection
In telecommunication and computing in general, a connection is the successful completion of necessary arrangements so that two or more parties (for example, people or programs) can communicate at a long distance. Continue Reading
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Definition
21 Sep 2005
well-known port numbers
The well-known port numbers are the port numbers that are reserved for assignment by the Internet Corporation for Assigned Names and Numbers (ICANN) for use by the application end points that communicate using the Internet's Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). Continue Reading
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Answer
08 Sep 2005
Placement of the firewall
In this expert response, Puneet Mehta tells us where the placement of the firewall should be architecturally. Continue Reading
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Answer
28 Aug 2005
Security of each level of the OSI model
What kind of security is associated with each level of the OSI model? Continue Reading
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Tip
19 Aug 2005
Router Expert: Standard interface configuration for a WLAN proxy server
Our router expert continues his series on building a secure WLAN with a Linux base. This article covers standard interface configuration of the http proxy server. Continue Reading
- Answer 03 Aug 2005
- Answer 20 Jul 2005
- Answer 19 Jul 2005
- Answer 11 Jul 2005
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Tip
27 Jun 2005
Wireless LAN deployment and federal regulations
A look at the bare minimum requirements to keep your WLAN compliant with federal regulations. Continue Reading
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Feature
22 Jun 2005
Router and firewall configuration
ITKnowledge Exchange member "stephang" had a question about the balance between blocking packets and enabling NAT on his router and on his firewall. Fellow forum members chipped in with their advice; check out what they had to say. Continue Reading
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Tip
16 Jun 2005
Secure WLAN best practices and topology
Expert Michael Martin provides a list of wireless security "dos and don'ts" and a sample topology for a secure WLAN. Continue Reading