excITingIP.com » Passive N/w Components

An introduction to Network Patch Panel

admin — Mon, 21 Sep 2009 11:25:11 +0000

Patch Panels are a part of structured network LAN cabling. Let us look at why they might be required, what are their major classifications and the disadvantages of network patch panels, in this article.

Photo courtesy: http://www.flickr.com/photos/stp/

As shown in the above diagram, patch panels are generally kept in the front of network switches, in the network racks. All the cables from the desktops are brought to the patch panels and they are terminated at the back side (The UTP cable consists of 4 Pairs, all these 8 cables are separated at the end and punched individually behind the patch panel). This is the permanent connection, which is not disturbed. A patch cable (with RJ-45 connectors at both ends) now goes from the front (a port) in the patch panel to one port of a network switch which is placed behind the patch panel.

But why introduce a new component in the already cluttered data centre? Can’t we just terminate the cables directly to the switch? Yes, it is fine to terminate the UTP cables from the desktops directly to the network switches. The set-up would still work. But a patch panel is introduced in between the network switch and the desktop cables for the following reasons:

¤ Identification: The patch panel ports can be labelled (Location, desktop number etc) to help identify which cable from which location is getting terminated on which port of the patch panel. Now, when there is a need for testing or disconnecting a particular cable, you could easily locate them on the patch panel.

¤ The switch is not disturbed, when small changes are being made with the network cabling. The changes can be made quickly and easily.

¤ All the cables can be terminated on the patch panels (irrespective of whether they need to be connected to the switches or not) and they could be selectively connected to the switches by just moving the patch cables, whenever needed.

¤ Testing: Patch panels help identify easily if the switch is not working or if there is any fault at the cable end. They also help in troubleshooting.

¤ It helps all the routine network monitoring tasks like testing, switching, routing etc. to be done quickly.

¤ The position of the patch cords, can be changed by anyone when there is an urgent need to do so, without having to wait for the network administrator. Or the network administrator can remotely guide the person performing the changes as it is easy to identify the routes and make changes.

¤ The active components like switches are kept behind the patch panels and hence direct tampering with them is difficult. The switches and their connections are permanently fixed, reducing the chances of error.
¤ Patch Panels come with cable ties and mounting hardware for efficient cable routing and management. It also looks neat this way.

¤ Some vendors offer patch panel management/monitoring software with sensors attached to patch cables which can monitor if any changes are made to the network and intimate the network administrator if any cables are changed, connected or disconnected. This helps identify and correct unauthorised tampering.

There are many types of patch panels. There are various patch panels based on the number of ports like 12 Port, 24 Port, 48 Port etc. There are also separate patch panels for Cat 5E, Cat 6, Cat 6A and cat 7 cables. So, if your switches support 1GE, your patch panels also need to support 1GE, only then you can realize 1GE in the edge port. There are different patch panels for UTP and Shielded pair cables. Patch Panels are also available as Flat Patch Panels or Angled Patch Panels (Here, the modules are angled at 45 degrees to increase the cable bend radius, in certain applications).

Disadvantages of Patch Panels: The network cabling, if done without patch panels, do not lose any functionality. So, they are actually redundant but an important component of structured cabling installations. The patch panels are quite expensive. They need to be upgraded (or changed) when the switches are changed to support higher bandwidth (The patch panel which supports 100 Mbps max. will not support 1000 Mbps when the network switches are upgraded to that level). There are also possibilities of errors during installation of patch panels as each UTP cable that needs to be fixed has 8 terminal cables which need to be punched according to a colour scheme.

excITingIP.com

In case you have any questions, you can contact us using the contact form or leave a comment below. You can also subscribe with your email address (on the right side of this site) to get intimated when a new article is published on this site.

Advantages and Dis-advantages of HDMI – High Definition Multimedia Interface

admin — Thu, 03 Sep 2009 20:51:48 +0000

This article gives a short introduction to HDMI, types of HDMI cables, advantages and dis-advantages of HDMI standard for carrying and displaying audio/video signals over their analog counterparts.

What is HDMI?

Do you remember the cables that you use to connect your DVD player with the TV? You could have used Composite audio/video cables or S-Video cables or Component video cables for HDTV. They all carry signals in the analog format (In component video, the signals are converted from digital to analog for transmission and reconverted to digital at the receiving end).

HDMI is the All-Digital interface where the signals are carried in digital format and hence there is no conversion required at either end. HDMI stands for High Definition Multimedia Interface. It is an all digital audio-video interface which carries signals in uncompressed format. It has been accepted by the consumer/ institutional electronics industry.

HDMI cables consist of 19 separate wires which carry high speed video, audio and other digital information. The digital audio and video data is encoded in to three colour channels and a clock channel.

Types of HDMI Cables:

Standard cables: They are also known as Category 1 HDMI cables. They perform at pixel speeds of 75 Mhz supporting bandwidth of about 2.23 Gbps. This is fine for carrying an uncompressed 1080i signal.

High Speed cables: They are also known as Category 2 HDMI cables. They perform at pixel speeds of 340 MHz supporting bandwidth of about 10.2 Gbps. They can handle the latest 1440p and WQXGA resolutions.

Advantages of HDMI:

¤ Higher Quality: HDMI enables loss-less transmission and better quality video at low brightness scenes at higher resolutions. So, the video quality is much better than their analog counterparts as there is no conversion involved either. High contrast details like text etc. are displayed more sharper.

¤ Intelligence: Two way communications between video sources are enabled by HDMI Interface, which enables automatic configuration (between 480p or 720p, 16:9 or 4:3 for example). So, external intervention to identify the best resolutions and audio formats is minimized. This is accomplished by using a standard known as EDID – Extended Display Identification Data.

¤ Authentication and Encryption: HDMI standard supports authentication to ensure that the devices are authorized to receive the content sent by the HDMI enabled sources. They also enable authentication to make sure that people cannot tap in to the cables to copy or pirate content sent through them.

¤ Signal Integrity: They enable digital signals to be stored, transmitted and viewed without changes from the original (unlike other media which require analog to digital conversion) and hence the signal degradation is not prominent. So, it is better to transmit HD content.

¤ Single Cable: This is truly a single cable solution as there is only a single cable that carries audio, video and control information. So, the complexity of implementing an audio video control system is lesser.

¤ Deep Colours: HDMI supports 10 bit, 12 bit and 16 bit (RGB or YCbCr) colour depths which can render over one billion colours in good detail.

¤ No Compression: Since HD signals are not compressed while transmission, there is no de-gradation in signal quality.

¤ Compatibility with DVI: Since it is backward compatible with DVI interface, DVI enabled PC’s can send HD content to display devices.

¤ Supports multiple audio and video formats: Multiple audio and video formats like standard stereo, multi channel surround sound, 720p, 1080i, 1080p, NTSC, PAL etc. are supported by HDMI standard.

¤ Hot Plug Detect: The sink device (display unit) can indicate its presence to a source with a hot plug detect signal to identify when a cable has been connected and to start authentication.

¤ CEC: Consumer Electronics Control is a communication link that enables devices connected via HDMI to talk to each other. For example, multiple DVD players from a single manufacturer can communicate with each other so that only one plays at a time. Some video sources can also send a power-off signal to turn off certain displays connected to it.

¤ Display port compatibility: Display port is a parallel technology for audio/video interface like HDMI and HDMI devices are compatible with Display Port interfaces.

¤ Dolby/DTS: HDMI supports Dolby/DTS-8 channel audio streams for highest quality.

Dis-advantages of HDMI:

¤ Distance Limitations: Maximum distance for HDMI Cat1 cables is up to 35 meters (approx) for full capacity and maximum distance for HDMI Cat2 cables is up to 10 meters (approx) for full capacity. Beyond this limit, they need extenders. There are extenders like UTP cable extenders for HDMI, HDMI cable extenders, Fiber extenders for HDMI and Coaxial extenders for HDMI. Even Switches, Distribution amplifiers, audio/video processors act as repeaters. But extending HDMI cables this way has its limitations.

¤ Switching Delays: Sometimes, blank screens can be caused due to authentication delays. There can also be screen flashing errors.

¤ Field Termination: There are limitations to field terminations of HDMI cables. They cannot be easily terminated in the field like their analog counterparts.

¤ Costly: HDMI cables are more expensive (per meter) than their analog counterparts.

¤ Multiple locations: They are difficult to run in multiple applications spanning various locations. There are more complexities in such situations than just the distance limitations.

¤ EDID: One such complexity is with EDID (Extended Display Identification Data) which is used in automatic identification of resolutions and audio formats. Both HDMI and EDID specifications offer limited guidance in multiple location deployment scenarios.

¤ CEC: The Consumer Electronic Format which enables the different devices to talk to each other becomes a problem when there is a central control system to control all the connected audio/video devices. It causes confusion when the devices themselves change their configuration as they might get undetected by the control systems.

¤ Multi-Channel Audio: While HDMI sources can transmit multi-channel audio sources, they cannot transmit multi-channel and standard two channel stereo signals at the same time (simultaneously). This becomes a problem with multi-room installations that has various devices supporting different audio formats.

¤ DVI Compatibility: HDMI devices are compatible with DVI interfaces but require a separate audio cable as DVI carries only video signals. It also needs a HDMI-DVI connector in such scenarios.

excITingIP.com

In case you have any questions, you could use the contact form to contact us or leave a comment below. You could also participate in the discussions in the Forum.

Power Over Ethernet (POE) and POE Injectors

admin — Fri, 17 Jul 2009 22:24:22 +0000

This article describes what is POE – Power Over Ethernet, how it helps transmit power along with data, what are POE Injectors, what are the types of POE Injectors, what a POE Injector management software does and some devices that support POE.

What is POE and why is it required?

Power Over Ethernet. That’s the expansion. You would have noticed a lot of devices connected to the IP Network Switches like Wireless Access Points, IP Phones etc. are not powered by a separate AC/DC source. Well, where do they get their power from? No, wireless power has not been discovered yet!

Power Over Ethernet (Specified by IEEE 802.3af and 802.3at Standards) enables electrical power to be carried along with data in the network cables (Cat x type) so that these devices need not be separately powered through a power source. It helps as devices like Access Points and IP Cameras are kept mostly at inaccessible places and carrying a power cable/adaptor may not be feasible and might increase the cost.

The Power Over Ethernet can be directly provided by IP Network Switches (Some switches are fully POE enabled on all the ports, while others have a few ports that can support POE) or it can be provided by POE Injectors, if the network switches are not POE enabled.

Single Port POE Injector:

A Single port POE Injector has two RJ-45 connections besides a power connectivity. This can selectively power one POE enabled device that is connected to it. There is a Cat x cable running from the switch to one of the POE injector ports and another long cable goes out from the next port (Carrying both power and data) to the network device that needs to be powered. POE Injector is kept close to the network switch so that it can utilize the power from the racks, UPS etc. Yes, POE Injector needs to be powered through AC/DC source!

Single port POE Injectors come with a standard 10/100 Mbps version and 10/100/1000 Mbps version to support 1GE Networks. They provide a maximum of 15.4W (approximately) and support IEEE 802.3af standards. Well, both the Power Over Ethernet Injector and the network device powered by it needs to support this standard. In situations like a single wireless access point being required for a conference room, there is no need buy a POE Enabled Switch on all ports!

High Power Applications:

There are certain devices like PTZ Camera, IEEE 802.11n access points etc. which needs a higher power (In the range of 30-40W or 60W) which cannot be given by the normal POE Injector. So, for such cases, there are special POE Injectors that need to be bought.

Multiple Port POE Injector:

Suppose, there is a 24 Port Switch (Without POE Capability) and you want all the 24 Ports to support devices with POE. You can either change the switch and buy a POE enabled Switch or buy a multiple port POE Injector. Well, this also looks like a switch! But instead of 24 ports, it has 48 Ports and a control port. So, each port of the switch is connected to one port of this multi-port POE Injector and each network device that needs to be powered is also connected to this multi-port POE Injector.

Management options for POE Injectors:

These POE Injector switches generally support SNMP v3, so you can manage them as a part of your Network Management Software (NMS) that supports SNMP v3. Or, certain POE Injector vendors offer a management software for these POE Injectors (Especially multi-port POE Injectors) that can do the following:

¤ Status display of each POE port.
¤ Activation/ Deactivation of POE per port that can be automatically scheduled (say switched off during weekends etc).
¤ Limit maximum power per port (For lower powered devices). Actually, the POE Injectors can do this themselves too.
¤ Give priority for each port, so that only the higher priority ports would be working when the power is down and the rest are automatically switched off.
¤ Enable SNMP Traps to notify you when any POE Ports are down.
And a lot more management features like Radius Integration, etc!! Talk about being proactive!

Some devices that support POE: Wi-Fi Access points, Wi-Max Access Points, IP Cameras, RFID Access Points, thin clients, IP Phones, IP Video Phones, etc.

excITingIP.com

In case you have any questions, you could get in touch with us via the contact form or leave a comment below. You could also participate in the discussions in the Forum.

Can you create a LAN IP network using telephone cables?

admin — Fri, 03 Jul 2009 11:56:38 +0000

This article analyses if the single pair copper cable networks, which are available in most of the organizations for providing voice connectivity through a local telephone exchange (EPABX) connecting all the analog phones, can be used to create an IP Network (Using DSLAM, CPE and ADSL2+ technologies), with a limited functionality in special cases.

I know, I need to pinch myself and wake up in the present! In this era of 10GE backbone ethernet chassis switches, Cat x, Fiber cables it is silly to explore a topic that might be outdated by atleast ten to fifteen years! But this can help some factories which are located in remote places and have no effective IP LAN network, but want to have one.

The point to note here is, any company would be having a telephone network. The single pair copper cables would be running to almost all the major places in such remote factories (It is good if they have fiber cables, Cat x cables, but we are discussing the other case – companies that don’t).

What people used to do in earlier days is (some even do now) - they have the Cat x cables to connect the computers in the computer room (or a department) and have LAN extenders which extend this small segment of LAN to other rooms or departments. This used to be the case especially if two departments are situated at a distance of more than 90 meters (as Cat x cables can’t go beyond that distance). They plug in the RJ-45 cables at one end of the LAN extender and connect the single pair copper cable at the other (some times multiple copper pairs) and the same set-up would be repeated at the other department. It seems you get around 2 Mbps of Upstream/Downstream bandwidth with one such inter-connecting copper pair. Well you could send a couple of mails between them and maybe share a couple of files – but that’s it. Generally each department has their own internet connectivity to share only among the local PC’s. There is not much of centralized network or services.

There is an alternate way to do almost the same thing but in a centralized manner by using the DSLAM’s, CPE’s and of course, the telephone cables. This takes advantage of the broadband technology – ADSL2+.

Imagine there is a huge factory (several departments located far away from each other). They have a telephone exchange, a Main Distribution Frame (Where all the cables are punched near the telephone exchange) and single pair copper cables running around the whole factory to give telephone connectivity. Of course these copper cables are bundled in to 20 pair, 40 pair etc while they are travelling around and are separated in the departments. Now, we want to have a functional IP network in this scenario without using fiber cables, cat x cables, switches etc. It is still possible!

We bring in an equipment called a DSLAM (Digital Subscriber Line Access Multiplexer) which is the smaller version of the one that a broadband service provider uses to give broadband connection to homes. We then hook this on in between the Telephone exchange and the Main Distribution Frame (MDF) so that all the lines go in to and out of the telephone exchange (EPABX) through the DSLAM. DSLAM supports direct internet connectivity – you can plug in 1 Mbps or higher bandwidth internet leased lines/ VPN’s directly to the DSLAM. Now let us come to the subscriber side – We need to place a CPE (which is actually a broadband modem) which connects to both the telephone and the computer. Yes, this set up needs to be replicated with every PC which wants to access the internet through the network. That’s it, you have a full fledged LAN IP network that can transmit data along with voice just using telephone cables! And yes, you can use both voice and data connectivity at the same time as this is broadband technology.

Well companies primarily use this to give internet connectivity to all their PC users, but even basic file transfers and email could work over such a network. But the problem with using ADSL2+ broadband technology is, the upload bandwidth is much lower than the download bandwidth. So, if the computers just need to be internet enabled, then this method could be effective. Each PC could get in excess of 10 Mpbs download stream – but that should still be ok, considering that the central internet leased line capacity is going to be less than that, in most cases.

Of course, this cannot be a replacement for LAN. But companies could use this method as a temporary arrangement (for some companies the temporary period could be even years!) till a full fledged LAN is created using the switches, fiber and cat x cables.

excITingIP.com

In case you have any questions, you could contact us using the contact form or leave a comment below. You could also participate in the discussions in the Forum.

An Overview of IP KVM Switches

admin — Fri, 26 Jun 2009 09:06:29 +0000

This article provides an overview of IP KVM Switches. We see what is an IP KVM Switch, what are the general capabilities of an IP KVM Switch, the security features of an IP KVM Switch, the type of data transmitted and the bandwidth consumed by the IP KVM Switch.

What is an IP KVM Switch:

A KVM switch is a hardware device that enables a user to control multiple computers/servers/network elements from a single keyboard, Video device and mouse. In fact, KVM switching stands for Keyboard Video and Mouse switching. This technology is particularly useful in a Data Center where multiple servers are located in a single place and there is no need to have a separate monitor, keyboard and mouse for each of them.

An IP KVM Switch is basically a KVM switch which works over IP Networks. It sees the various servers through their IP addresses, uses IP infrastructure including the LAN cabling to control the servers, and one main advantage it provides is to remotely control the data center servers.

Capabilities of an IP KVM Switch:

The general capabilities of an IP KVM Switch include remote access and management of servers and network devices. One can also manage virtual servers through a specialized software provided by some of the vendors. The remote access can be done through a browser (web-based), and alternately some of them offer specialized software through which the management can be done. Some of them even support an external modem.

The main advantage of IP KVM Switches is that they offer BIOS level support. They can manage a certain number of servers based on the number of ports that they have (and there is a maximum number of remote devices that can be supported by every IP KVM Switch). The IP KVM Switch transmits the video of the server output over IP, to the controlling station so that the server output can be seen over a remote station and can be controlled. Even the key-board press and mouse movements are transferred over the network to the server. There are USB ports for the key-board and mouse to connect.

While multiple IP KVM Switches can be cascaded and a centralized management for all of them is possible, some of them even offer centralized power management (The power of the servers can be cycled on or off via the power control port). Some vendors support remote media by mapping local media (like CD drives etc.) to a remote server to transfer files or other operations.

Types of data transmission and bandwidth:

In an IP KVM Switch, there are three types of data that are being transmitted between the control station and the servers over LAN. This enables effective management of the servers. They are:

¤ Management data: These are used to start, maintain and terminate the KVM Sessions. They are required for authentication, access control etc. But these type of data occupy very less bandwidth in the LAN.
¤ Keyboard and Mouse data: When a keyboard is pressed in a control station, the make and break of the keys are transmitted over the network to the servers. Same way, the mouse movements and the clicks are also transmitted through a set of messages. This happens with each mouse click/ keyboard press and this also doesn’t occupy much bandwidth in the LAN.
¤ Video data: The screen shot of the server is sent by a video stream. It employs loss-less compression, unlike video conferencing systems, so it occupies more bandwidth. But generally the video data is encoded using a compression algorithm, which sends only the changes from previous video frame and not the entire blocks of video data. This reduces the amount of bandwidth consumed. The bandwidth consumed might be anywhere between 1.5 to 20 Mbps based on the no. of concurrent users (For a 16 port switch).

There are some bandwidth optimization techniques employed by certain IP KVM Switch vendors like when a particular viewing session is minimized in the tool bar, the video stream for that particular session is turned off until the window is re-opened and when multiple windows are opened, any window that is not in focus is updated less frequently.

Security features of an IP KVM Switch:

¤ Authentication and Access control: Some of the IP KVM Switches can integrate with corporate directories like LDAP and provide a centralized authentication of the users and their roles can be determined. Based on their role, they can be selectively offered access only to certain servers or all servers. This provides one more layer of security for combating internal threats and avoids un-necessary tampering of the servers by those who are not authorized to use it.
¤ Encryption: All the data between the KVM Switches and the servers are encrypted by some vendors by using 128 bit SSL/ 3DES standards based encryption.
¤ Failover: Some IP KVM Switch vendors support port mirroring and failover. If one server connected to one port fails, the operation can be seamlessly transferred to a back up server (If any) in another port with all its access rights etc. intact. This provides redundancy.
¤ https remote access: Since remote locations access the server through a browser, IP KVM Switches provide access to them via the secure protocol https.
¤ Logs and session termination: Most of the IP KVM vendors provide the usage reports, logs of the failed attempts etc. to help monitor and audit the anomalous behaviour. Some vendors send the key-strokes required to log out any user when the session is terminated unexpectedly. This helps block the security hole created by not logging out of the session.

excITingIP.com

If you have any questions, you could use the contact form to contact us or leave a comment below. You can also participate in the discussions in the Forum.

An overview of passive components in a Local Area Network

admin — Fri, 15 May 2009 13:22:07 +0000

This article discusses the advantages of passive components in a network, introduction to popular passive components like copper cables, optic fiber cables and racks.

Why are Passive components exciting in a LAN network(Advantages)?

¤ Passive components provide the physical connectivity between the various network devices.
¤ They provide a medium to transfer data in a relatively high speed (Bandwidth) between the network devices.
¤ They help in connecting devices over greater distances.

Copper cables:

Copper cables are the UTP – Unshielded Twisted Pair Cables which are also called as Catx cables in a LAN network. They are cheaper than fiber and faster to set up. They don’t require the detailed splicing requirements of the fiber cables and anyone with a basic level expertise can set them up. They are very common for connecting the end user computers/laptops/printers etc. to the Network Switches. They are also used in the interconnectivity of the Switches and sometimes interconnectivity of two separate buildings/departments. The main disadvantage of copper cables is the distance limitation. They can give a lossless performance only up to 90 meters and after that the signals have to be boosted using another switch or a repeater as the losses tend to be pretty high. There are various categories (Cat) of UTP Copper cables and the popular ones and the bandwidth supported by them are given below:

Cat5 Cables – Support 100 Mbps up to 90 meters.
Cat5E Cables – Support I Gbps up to 90 meters.
Cat6a Cables – Support 10 Gbps up to 90 meters.
Cat7a Cables – Expected to support up to 40 Gbps in the future.

The accessories for UTP copper cables include patch cord, RJ45 Connectors, crimping tools etc.

Fiber Cables:

Unlike the copper cables, which carry data through electrical signals, the fiber cables carry data through optical (light) signals which are propagated through a narrow core of the fiber, which is a non conductive substance. There are two modes of fiber optic communications – Single mode and multi mode.

The advantages of Fiber optic cables:

¤ Can propagate the light signals through a longer distance (Usually upto 2 Km) and in special cases, even higher without the need of a repeater in between to boost the signals.
¤ Can support the higher bandwidth requirements of a demanding network as multiple cores are generally intertwined in the same cable. It uses one core for transmission and one core for reception of light signals.
¤ Fiber optic cables are immune to the EMI – Electro Magnetic Interference (Which affect the copper cables when carried along with the power cables).
¤ There is no risk of a spark or a shock which the copper cables are prone to as they carry current and hence the fiber optic cables can be used in electrically sensitive areas like chemical plants etc as they are safer.
¤ It is impossible to tap through a fiber optic cable in the same way that it is done with a copper cable. So, the transmitted data is secure on the way.

Disadvantages of optical fiber cables include the higher cost and the greater expertise required to splice and install the OFC set up. But these costs are coming down fast.

Optical fiber cables are generally used to connect the various Network Switches and are also useful for the long distance connectivity.

Network Racks:

The network racks are used to house the servers, switches, routers and all the other electronic components of a data centre. Usually, since the data centre space is highly critical the various components of the data centre needs to be arranged neatly one on the top of another and yet be accessible to carry out maintenance activities. Racks provide the platform to do so. Racks are either open ended, or closed from two sides. They are either fixed or movable. They house the network equipments (19 inch form factor is the most common form factor for holding in a rack) and come with the cable managers to neatly carry cables through them. They may also come with power connectivity and fans to cool the network equipment which can generate a lot of heat.

So, we just got an overview of the basic passive components used in a LAN network.

excITingIP.com

In case you have any specific questions, you could contact us using the contact form or leave a comment below. You could also participate in the discussions in the Forum.