Ask the Experts

Ask the Experts

• Should I use the OpenFlow protocol in software-defined networks?

  The OpenFlow protocol isn't required for SDN, although the Open Network Foundation recommends it, which means networking vendors have options.  Continue Reading

• Why do I need SDN technology?

  SDN is valuable, but uses extend to other parts of the network for increased network flexibility, dynamic traffic flow, decreased latency and QoS.  Continue Reading

• Is SDN a centralized or distributed network architecture?

  A software-defined network can have a centralized or distributed network architecture in the data center, LAN and WAN, depending on business needs.  Continue Reading

• What is the difference between an overlay network and SDN?

  A software-defined network can be deployed as an overlay network to a physical network or natively as the primary network to improve flexibility.  Continue Reading

• Does software-defined networking require special SDN switches?

  Software-defined networks do not require special SDN switches; instead, vendors offer a variety of SDN controllers, network fabrics and hardware.  Continue Reading

• Where do network fabric and SDN technologies intersect?

  Networks can use a network fabric and SDN technologies together, and vendors' SDN architectures integrate them in a variety different ways.  Continue Reading

• The role of northbound APIs in an SDN environment

  Northbound APIs on SDN controllers enable applications and orchestration systems to program the network and request services from it.  Continue Reading

• SDN, network virtualization: Are they the same?

  Despite differences, SDN and network virtualization share common elements to direct network resources to VMs and segment or consolidate networks.  Continue Reading

• Do I need to use an SDN controller for software-defined networking?

  An SDN controller, with or without OpenFlow, is not required for a software-defined network, and SDN architecture vendors take different approaches.  Continue Reading

• How do cloud elasticity and cloud scalability differ?

  Cloud elasticity and cloud scalability are both characteristics of cloud services, but support different goals, says cloud expert Chip Popoviciu.  Continue Reading

• Application performance management should include packet capture

  Expert Jesse Rothstein explains the importance and challenges of packet capture abilities in application performance management (APM) solutions.  Continue Reading

• What are the benefits of IPv6 in SDN and network virtualization?

  One of the benefits of IPv6 is that it makes software defined networking and network virtualization scale easily, IPv6 expert Ciprian Popoviciu says.  Continue Reading

• What are some of the challenges of running a dual-stack IPv6 cloud?

  When running a dual-stack IPv6 cloud, you must remember that the two protocols share infrastructure resources, says IPv6 expert Ciprian Popoviciu.  Continue Reading

• How the 802.11ac standard impacts security

  The upcoming 802.11ac standard is an improvement over 802.11n, but how could security be impacted? Wireless expert Lisa A. Phifer explains.  Continue Reading

• What's the difference between WAN optimization and WAN acceleration?

  Expert Howard Hooper compares and contrasts WAN optimization and WAN acceleration in this Ask the Expert response.  Continue Reading

• Wireless network setting considerations for Android troubleshooting

  Wireless expert Lisa Phifer addresses Android troubleshooting and the ways that changing wireless network settings could solve connectivity problems.  Continue Reading

• Are active-active network configurations possible over MPLS?

  Telecom expert Mike Jude explains how to create an active-active network configuration for load sharing and backup in an MPLS implementation, in this expert response.  Continue Reading

• What areas should we focus on when building a cloud data center?

  Building a cloud data center requires a lot of planning, and certain areas will receive more attention than others, says managed services expert Lauren Robinette.  Continue Reading

• Overcoming wireless network interference in public venues

  In public venues, unplanned personal hotspots can cause wireless network interference. Wireless expert, Lisa Phifer explains how to overcome this and maintain Wi-Fi coverage.  Continue Reading

• How can I allow and restrict user access on my VPN client?

  Rainer Enders explains how to allow certain users to access a VPN client while restricting others.  Continue Reading

• How do I disable VPN passthrough? What are the pros and cons to disabling it?

  In this Ask the Expert response, Rainer Enders explains how to disable VPN passthrough and what the benefits and drawbacks are.  Continue Reading

• Why am I able to ping but not do tracepath over my Layer 3 VPN?

  Our VPN expert explains why a Layer 3 VPN can ping but not do a tracepath from the client in this response.  Continue Reading

• Cisco switch configuration for a Cisco 3560 switch

  Get configuration guidelines for a Cisco 3560 switch in this expert response.  Continue Reading

• Do Layer-3 MPLS VPNs need to have BGP-4 support?

  In this Ask the Expert response, VPN expert Rainer Enders explains why BGP-4 support is necessary when configuring a router for a Layer-3 MPLS VPN.  Continue Reading

• How can we make our cloud data center more energy efficient?

  An energy-efficient cloud data center offers more than bragging rights; it saves serious cash. Data center expert Marshall Bartoszek shows how cloud providers can go green.  Continue Reading

• What are the types of MPLS VPNs?

  In this Ask the Expert response, VPN expert Rainer Enders breaks down the types of MPLS VPNs and explains their differences.  Continue Reading

• Why am I experiencing issues with VoIP over VPN?

  In this Ask the Expert response, VPN expert Rainer Enders discusses why one may experience issues with VoIP over VPN and offers solutions to solve the problems  Continue Reading

• How secure is a PPTP VPN in comparison with other types of VPNs?

  In this Ask the Expert response, VPN expert Rainer Enders discusses the lack of safety associated with PPTP and offers these safer VPN solutions.  Continue Reading

• Best cloud services go-to-market strategies for network operators?

  Cloud expert Marshall Bartoszek details the primary strategies and approaches that network operators are choosing to deploy as they go to market with cloud services.  Continue Reading

• Wi-Fi and LAN issues: Attaining simultaneous network connections

  Wi-Fi and LAN connections may be difficult to run together using Windows XP and Windows 7, yet Wireless Expert, Lisa Phifer offers advice on simultaneous network connections.  Continue Reading

• What does IPv6 mean for IPsec VPNs?

  In this Ask the Expert response, VPN expert Rainer Enders discusses what IPv6 means for IPsec VPNs.  Continue Reading

• What is VPN-as-a-service and how does it work?

  In this Ask the Expert response, VPN expert Rainer Enders discusses what a virtual private network as a service (VPNaaS) is and how it works.  Continue Reading

• What is a cloud virtual private network (VPN)?

  In this Ask the Expert response, VPN expert Rainer Enders discusses what a cloud virtual private network (VPN) is and what its benefits are.  Continue Reading

• Ad hoc network creation: Overcoming personal wi-fi hotspot competition

  Ad hoc network creation is rising due to personal wi-fi hotspots from smartphones and computers. Addressing its impact on your WLAN is key to overcoming potential interference.  Continue Reading

• How many types of data centers are there?

  How many types of data centers are there? Cloud data center expert Marshall Bartoszek parses some of the different flavors of data center that providers and enterprises employ.  Continue Reading

• When military radar causes fixed broadband wireless interference

  Military radar may cause fixed broadband wireless interference. This expert tip explains tests and ideas to check if this is the case and how to address this interference.  Continue Reading

• Fixing CRC errors: Know your wireless router coverage area boundaries

  Distance between devices may cause interference in your wireless router coverage area and CRC errors to pop up. This expert tip offers advice for fixing CRC errors.  Continue Reading

• Unauthorized network access: Neighbors pose a network security threat?

  Unauthorized network access from a corporate neighbor or employee poses a serious network security threat and is considered theft of service. This tip explains why.  Continue Reading

• How do content provider networks and service provider networks differ?

  Optical networking expert and ACG Research managing partner Eve Griliches breaks down the differences between content provider networks and service provider networks.  Continue Reading

• Wi-fi replacing Ethernet? An expert weighs in on the possibilities

  Wireless expert, Lisa Phifer addresses a query regarding Wi-Fi replacing Ethernet. Lisa provides analysis, advantages and disadvantages, and future expectations of both.  Continue Reading

• 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

• Expert advice for file server troubleshooting

  Network administration expert, Lindi Horton answers a query regarding file server troubleshooting. She explains potential reasons for file server issues, and things to check to solve the problem.  Continue Reading

• What advantages do 4G wireless networks have over 3G networks?

  Yes, 4G represents a technological step beyond its 3G predecessor. But how exactly are 4G wireless networks more advanced than 3G networks? Telecom expert Mike Jude breaks it down.  Continue Reading

• How do Infrastructure as a Service and multi-tenant services differ?

  Telecom networking expert Ivan Pepelnjak details the similarities and differences between Infrastructure as a Service (IaaS) and multi-tenant services.  Continue Reading

• What are the benefits of MPLS VPN/VPLS connections?

  Telecom networking expert Ivan Pepelnjak breaks down the speed, bandwidth and security benefits of moving from a simple cable Internet connection to an MPLS VPN or VPLS connection.  Continue Reading

• Packet vs. circuit switching data networks: An expert explains the differences

  Network administration expert, Lindi Horton answers a query regarding packet vs. circuit switching in regards to data networks by using an analogy to help explain the concept of both.  Continue Reading

• Breaking down radio configuration parameters in 3G networks

  Every cell phone call consists of a complex sequence of events governed by radio configuration parameters in 3G networks. Wireless expert Mike Jude breaks down the process.  Continue Reading

• Why enhance Wi-Fi ad hoc mode? Most go with Wi-Fi Direct

  Wireless expert, Lisa Phifer explains that it may not be worth enhancing Wi-Fi ad hoc mode since Wi-Fi Direct is a better alternative for enabling two stations to communication directly.  Continue Reading

• Expert tips to solve port 3389 issues when end users gets blocked

  Enterprise security expert, Michael Gregg answers a question regarding port 3389 issues when a user tries to open port 3389 RDP on their router to work from home, but hits a roadblock when the ISP blocks the port.  Continue Reading

• Mi-Fi and Android smartphone mobile hotspot comparison

  Wireless expert Lisa Phifer responds to a question regarding a Mi-Fi and Android smartphone mobile hotspot comparison. She provides an in depth analysis of both mobile hotspots, and also examples for uses of both.  Continue Reading

• How can service providers limit peer-to-peer (P2P) traffic in routers?

  It's notoriously hard to limit peer-to-peer (P2P) traffic, but IP expert Ivan Pepelnjak has some ideas on how service providers can deal with nettlesome P2P traffic jams.  Continue Reading

• Be aware of Wi-Fi security to deal with Firesheep at public hotspots

  Wireless expert Lisa Phifer tackles public Wi-Fi security and the steps you can take to protect yourself from sidejacking attempts like Firesheep. Lisa also highlights that these threats are not limited to public Wi-Fi access alone, and could happen...  Continue Reading

• Deciding between passive optical networks and active optical networks

  Fiber expert David Hashman details the key design and other elements to consider when deciding whether to deploy a passive optical network (PON) or an active optical network (AON).  Continue Reading

• Disadvantages to a layered approach

  Security expert Michael Gregg discusses the disadvantages to a layered approach to enterprise security.  Continue Reading

• Making sure your FTTH GPON installation is ready for turn-up

  Fiber expert David Hashman details what you must know when accepting the fiber installation for gigabit passive optical networks, from testing requirements to reference values.  Continue Reading

• Wireless access for mall kiosk

  Wireless expert Lisa Phifer answers a question on how to connect wired networked devices to a mall's wireless access.  Continue Reading

• Designing WiFi access for a hotel

  Wireless expert Lisa Phifer tackles the basics of providing wireless access in a hotel.  Continue Reading

• What are the advantages of Ethernet in an access network?

  Telecom networking expert Ivan Pepelnjak only sees one advantage to using Ethernet technology in access networks. Learn what it is, plus three tips for managing per-user bandwidth.  Continue Reading

• What are the advantages of DWDM over a virtual switching supervisor?

  IP expert Ivan Pepelnjak explains how comparing dense wavelength division multiplexing (DWDM) to virtual switching supervisors (VSS) would be like "comparing a car to a highway."  Continue Reading

• What are the specified launched power and receive sensitivity of GPON and PtP networks?

  Fiber expert David Hashman details launched power and receive sensitivity specifications for gigabit packet optical networks and active Ethernet point-to-point networks.  Continue Reading

• Access point problems running on PoE

  Powering a wireless access point using Power over Ethernet is usually a straightforward process, but troubleshooting an issue can be tricky. Wireless expert Lisa Phifer steps through some possible solutions and where to look for additional help in ...  Continue Reading

• Linking an unmanaged switch and DHCP server

  Unmanaged Linksys switches don't know where to send BootP and DHCP requests. Find out what to do to fix the problem of unmanaged switches and DHCP servers.  Continue Reading

• How to troubleshoot slow VPN connections

  Suffering slow VPN connection? Try checking VPN concentrators and caching.  Continue Reading

• Extending 802.11n wireless LAN and connecting two WLANs

  Extending 802.11 WLANs inside a large office can be done by bridging access points together, while outdoor mesh solutions can be used to connect two WLANs between buildings on a small campus.  Continue Reading

• What is the difference between MPLS and normal IP?

  Telecom networking expert Ivan Pepelnjak explains what separates Multiprotocol Label Switching (MPLS) forwarding from standard Internet Protocol (IP) forwarding.  Continue Reading

• OSS vs. NMS: What are the similarities and differences?

  What's the difference between operations support systems (OSS) and network management systems (NMS)? Telecom networking expert Ivan Pepelnjak has the answer.  Continue Reading

• What is the status of 100G transmission speed in optical transport networks?

  ACG Research managing partner Eve Griliches offers an update on the development of 100 gigabit per second (100G) transmission speed in optical transport networks (OTN).  Continue Reading

• I am designing an underground outside plant (OSP) Fiber to the Home (FTTH) network. What kind of con

  Fiber expert David Hashman compares polyvinyl chloride (PVC) and high-density polyethylene (HDPE) as conduit for underground outside plant (OSP) Fiber to the Home (FTTH) networks.  Continue Reading

• I am starting a Fiber to the Home (FTTH) project. Which is better for my FTTH deployment, a passive

  Fiber expert David Hashman explains the pros and cons of passive optical network (PON) and active Ethernet (Active-E) network technologies for Fiber to the Home (FTTH) deployment.  Continue Reading

• Do I need 802.11n wireless adapters for laptops and PCs to install 802.11n?

  You don't need 802.11n wireless adapters for your laptops or PCs in order to install 802.11n and make use of 802.11n MIMO since most 802.11n APs are backward compatible, but you may need new client hardware.  Continue Reading

• How will Multiprotocol Label Switching (MPLS) interact with MPLS-TP in the future?

  Telecom networking expert Ivan Pepelnjak considers how service providers may approach interaction between Multiprotocol Label Switching (MPLS) and MPLS-Transport Protocol (MPLS-TP).  Continue Reading

• What are the benefits of a Multiprotocol Label Switching-based Border Gateway Protocol-free core?

  Learn the pros of using an Multiprotocol Label Switching (MPLS)-based Border Gateway Protocol (BGP)-free core, including how freeing core routers of BGP can stabilize networks.  Continue Reading

• Configuring VLANs on a Cisco Catalyst 3750 and Catalyst 2950 together

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• How does User-based Rate Limiting (UBRL) do if I have oversubscribed a port or switch?

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• Can I use MPLS Traffic Engineering with IPv6?

  Wondering how to reap the benefits of MPLS Traffic Engineering features with IPv6? Expert Ivan Pepelnjak has your answer.  Continue Reading

• What's the difference between DWDM and CWDM?

  Expert Ivan Pepelnjak explains the primary differences between dense wavelength division multiplexing and coarse wavelength division multiplexing (DWDM and CWDM).  Continue Reading

• Where do you think WiMAX technology will be used?

  As major service providers tap Long-Term Evolution for 3G network upgrades, a question arises: What's next for WiMAX technology? Expert Ivan Pepelnjak looks at the future of WiMAX.  Continue Reading

• How does traffic grooming for optical networks work?

  Wondering how traffic grooming for optical networks works? Learn the ins and outs from our expert, Ivan Pepelnjak.  Continue Reading

• What network troubleshooting tools can I use to determine the cause of slow web page access?

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• How does Active Directory for Cisco ACS work?

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• What is the difference between IP address and machine address?

  Do you know the difference between an IP address and a machine address? Find out in this Ask the Expert response.  Continue Reading

• Frame relay vs. ATM networks: What's the difference?

  Want to know the difference between frame relay and ATM networks? Find out in this expert response.  Continue Reading

• How does rain affect wireless network data transfer?

  In one of the wireless data acquisition installations, there is no data transfer during rain and mist. The wireless system works in 2.4 GHz frequency. What could be the cause of this?  Continue Reading

• How can I increase throughput on my wireless mesh network?

  We have installed a wireless mesh network that connects two access points (APs) to mesh nodes that are mounted at 25 meters high on 23 light poles. Poles are distributed around a container yard that measures 650 meters by 1,000 meters. There are six...  Continue Reading

• Why is the 802.11g Wi-Fi throughput speed on my smartphone slow?

  I recently purchased a smartphone with Wi-Fi (802.11g) but found video over Wi-Fi to be pretty choppy. I checked SpeedTest and I don't get anywhere near 54 Mbps when connected to Wi-Fi. Why not?  Continue Reading

• How do I set the Web page default on a network of computers without setting them all individually?

  Learn how to set a default for a network of computers if a group policy isn't working. Instead of setting each machine manually, learn what else you can do.  Continue Reading

• How do I change my security setting to allow ActiveX?

  Learn how to change your security settings to allow ActiveX in Internet Explorer 6 or later, from our enterprise security expert Michael Gregg.  Continue Reading

• How many wireless base stations can connect to 802.11g access points?

  Our wireless networking expert, Lisa Phifer, talks about the information you need in order to support additional clients on 802.11g access points (APs), in this advice.  Continue Reading

• What is wireless networking?

  Are you looking for resources on wireless networking and a definition to define this concept? Then view this expert answer.  Continue Reading

• How can I calculate perimeter firewall throughput?

  Learn how to use a capture filter in Wireshark, to determine network throughput on a firewall by monitoring incoming packets and using a simple equation to find a baseline throughput, from our expert Michael Gregg.  Continue Reading

• Why is access denied to my Active Directory (AD) users and computers?

  Learn how to troubleshoot administrative domain access errors on your network in your Active Directory user list from our expert, Lindi Horton.  Continue Reading

• APs drop connection in WLAN configured as a wireless mesh network

  Learn how to network troubleshoot a Colubris MSC 3200 access point/controller in a 16-access-point networking environment, each with unique static IPs that drop the Internet connection, from our expert Lisa Phifer.  Continue Reading

• What is network infrastructure and what is a hybrid network?

  Learn specific networking terms to help setup and choose a specific type of network infrastructure from a single proprietary company or a hybrid of vendors, from our expert Tessa Parmenter.  Continue Reading

• What preventative maintenance procedures for network equipment exist?

  Learn the best practices for monitoring and maintaining your Cisco IP equipment based on potential fault and performance management best practices, from our expert Lindi Horton.  Continue Reading

• Do I have to disable DHCP on my router to create a DHCP server?

  Learn how to turn off DHCP properly in order to use a DHCP server that is configured on a Windows server, and ensure that your routers are not acting as DHCP servers, from our expert Lindi Horton.  Continue Reading

• Will using a VPN protect me against fake wireless hotspots?

  Learn how to avoid data theft from phishing or connecting to a fake hotspot, by using a VPN, and various other secure browsing techniques, from our expert Lisa Phifer.  Continue Reading

• Is there VLAN software recommend for Realtek NICs?

  Find out which VLAN (virtual local area network) software recommendations and device drivers are the best solutions for your Realtek NIC, from our expert, Lindi Horton.  Continue Reading

• Top 10 reasons why computers do not have network access to each other

  Learn 10 useful tips from our expert on how to troubleshoot a network in which one computer will not allow password permissions or access because of several common network environmental issues.  Continue Reading

• How can I replicate the services of Active Directory (AD) in ADC?

  Learn how to replicate AD services in ADC (Active Directory Controller) by creating policy replication agreements between two or more servers, from our expert.  Continue Reading

• Which Q&A brain dump sites will help me prepare for the CCNA exam?

  Becoming a Cisco Certified Network Associates (CCNA) takes much more than memorizing brain dumps or taking short cuts to pass the exam. Get advice on the best way to approach CCNA certification from our expert David Minutella.  Continue Reading