Posts with #networking tag
As the standard cables that are commonly used to connect a modem to a router, and to connect a router to a computer’s network interface card (NIC), Ethernet cables have many different categories, such as Category 3, Category 5, Category 5e, Category 6, Category 6a, and Category 7. These types of Ethernet Cables have been developed, and each category has different specifications as far as shielding from electromagnetic interference, data transmission speed, and the possible bandwidth frequency range required to achieve that speed. It may be hard to decide which one you need while looking at all the available options for Ethernet cabling. Actually, the category of cable is usually clearly printed on the cable’s sheath, so there can be no doubt as to the type of cable being used. But do you know about the main differences between these categories of Ethernet cable? So in the following part we will tell about the main features of each type of Ethernet Cable.
Category 3 Ethernet cable, also known as Cat 3 or station wire, is one of the oldest forms of Ethernet cable still in use today. It is an unshielded twisted pair (UTP) cable that is capable of carrying 10 megabits per second (Mbps) of data or voice transmissions. Its maximum possible bandwidth is 16 MHz. Cat 3 cable reached the peak of its popularity in the early 1990s, as it was then the industry standard for computer networks. With the debut of the faster Category 5 cable, however, Cat 3 fell out of favor. It still can be seen in use in two-line telephone systems and older 10BASE-T Ethernet installations.
Category 5 (Cat 5) Ethernet cable is the successor to the earlier Category 3. Like Cat 3, it is a UTP cable, but it is able to carry data at a higher transfer rate. Cat 5 cables introduced the 10/100Mbps speed to the Ethernet, which means that the cables can support either 10 Mbps or 100 Mbps speeds. A 100 Mbps speed is also known as Fast Ethernet, and Cat 5 cables were the first Fast Ethernet-capable cables to be introduced. They also can be used for telephone signals and video, in addition to Ethernet data. This category has been superseded by the newer Category 5e cables.
The Category 5e standard is an enhanced version of Cat 5 cable, which is optimized to reduce crosstalk, or the unwanted transmission of signals between data channels. This category works for 10/100 Mbps and 1000 Mbps (Gigabit) Ethernet, and it has become the most widely used category of Ethernet cable available on the market. While Cat 5 is common in existing installations, Cat 5e has completely replaced it in new installations. While both Cat 5 and Cat 5e cables contain four twisted pairs of wires, Cat 5 only utilizes two of these pairs for Fast Ethernet, while Cat 5e uses all four, enabling Gigabit Ethernet speeds. Bandwidth is also increased with Cat 5e cables, which can support a maximum bandwidth of 100 MHz. Cat 5e cables are backward compatible with Cat 5 cables, and can be used in any modern network installation.
One of the major differences between Category 5e and the newer Category 6 is in transmission performance. While Cat 5e cables can handle Gigabit Ethernet speeds, Cat 6 cables are certified to handle Gigabit Ethernet with a bandwidth of up to 250 MHz. Cat 6 cables have several improvements, including better insulation and thinner wires, that provide a higher signal-to-noise ratio, and are better suited for environments in which there may be higher electromagnetic interference. Some Cat 6 cables are available in shielded twisted pair (STP) forms or UTP forms. However, for most applications, Cat 5e cable is adequate for gigabit Ethernet, and it is much less expensive than Cat 6 cable. Cat 6 cable is also backwards compatible with Cat 5 and 5e cables.
Category 6a cable, or augmented Category 6 cable, improves upon the basic Cat 6 cable by allowing 10,000 Mbps data transmission rates and effectively doubling the maximum bandwidth to 500 MHz. Category 6a cables are usually available in STP form, and, as a result, must have specialized connectors that ground the cable.
Category 7 cable, also known as Class F, is a fully shielded cable that supports speeds of up to 10 Gbps (10,000 Mbps) and bandwidths of up to 600 Mhz. Cat 7 cables consist of a screened, shielded twisted pair (SSTP) of wires, and the layers of insulation and shielding contained within them are even more extensive than that of Cat 6 cables. Because of this shielding, they are thicker, more bulky, and more difficult to bend. Additionally, each of the shielding layers must be grounded, or else performance may be reduced to the point that there will be no improvement over Cat 6, and performance may be worse than Cat 5. For this reason, it’s very important to understand the type of connectors at the ends of a Cat 7 cable.
The following table summarizes the most common types of Ethernet cables, including their maximum data transmission speeds and maximum bandwidths.
Maximum Data Transmission Speed
Category 5 e
UTP or STP
Category 6 a
With each successive category, there has been an increase in data transmission speed and bandwidth. To fully future-proof a network installation, the highest categories are recommended, but only if all of the other equipment on the network is capable of similar speeds. Otherwise, expensive cables will be only as fast as the slowest piece of hardware on the network.
Ethernet Cable Connectors
The ends of Ethernet cables that connect into a NIC, router, or other network device are known by several names. Modular connector, jack, or plug are the most commonly used terms. Shorter lengths of Ethernet cable are usually sold with the connectors already installed, but for custom installations requiring longer lengths, cable is often sold in bulk quantities, and connectors must be installed on the ends.
The most common type of connector for Ethernet installations is referred to as an "RJ-45" connector. It is officially known as an 8P8C connector, but this term is rarely used in the field, and the term "RJ-45" which was the telephone industry’s term for this connector’s wiring pattern, has become the customary colloquial name for the connector itself. Categories 3 through 6 all use the RJ-45 connector, but Cat 7 utilizes a specialized version of the RJ-45 called the GigaGate45 (GG45), which grounds the cable and allows for higher data transmission rates. There are two standard pin assignment configurations for RJ-45 connectors: T568A and T568B. The T568A standard is typically used in home applications, while T568B is used in business applications.
In every case, the specifications of the cable, such as its category, whether or not it is shielded, and whether or not it needs to be grounded, must match the specifications of the connector. For those who are confused or uncertain about crimping and installing connectors to cables manually, it is best to buy cables that already have connectors professionally installed.
Other Qualities of Ethernet Cables to Consider
There are a few important considerations that apply to all Ethernet cables. Data transmission rate and bandwidth both decrease with the increase of cable length, so the shorter the length, the better. For 10/100/1000BASE-T networks (those that have maximum speeds of 10, 100, or 1000 Mbps, including all the aforementioned cable types except for Categories 6a and 7), 100 meters is the maximum allowable cable length before the signal will degrade. For category 6a cables running at 10 Gbps speeds, 55 meters is the maximum allowable length, and even this length is only allowed in very good alien crosstalk conditions, or areas of low interference, such as when the cable is located far away from other cables that could cause interference.
There are some other terms regarding cable terminations that can complicate the shopping experience. Some cables are referred to as patch cables, while others are called crossover cables. Even though crossover and patch cables may look the same, they function differently. A patch cable is one that terminates with the same type of connector standard at both ends. The connectors terminating a patch cable can use the T568A or T568B standards, but both ends must be the same. A crossover cable, on the other hand, has one end that terminates in a T568A connector and another that terminates in a T568B connector. Patch cables are used to connect devices that are different from one another, such as a switch and a computer. Crossover cables are used to connect similar devices, as when a switch is connected to another switch, for example.
Another important distinction in Ethernet cables is whether they contain solid or stranded conductors.
Solid conductor cables have one solid wire per conductor, while stranded conductor cables have several strands of wire (typically seven) wrapped around each other to form a single conductor. Each type has its own advantages and disadvantages. Solid conductor cables are best for fixed wires within the walls or structure of a building. The single conductors are sturdy enough to be punched down into wall jacks and patch panels, but not as easy to install into a typical RJ-45 connector. Stranded conductors, on the other hand, can fray when punched down into wall jacks, so they are better suited to be crimped into an RJ-45 connector. They are also more flexible and forgiving when bent at sharp angles, so they are better suited for patch cables and applications where the cable may be rolled up or otherwise moved around.
So when you’re setting up an Internet connection in your home or office, you’ll need to obtain the proper Ethernet cable to attach your computer to the modem. While connecting the cable is typically a simple task, finding the right one may be a bit more complex. While Ethernet cables may all look similar to one another, their specifications vary widely. It’s important to research what type of cable will work with your equipment, and you’ll also want to consider things like the price and quality of the cable, as well as the types and number of devices you’ll be connecting to your network. You could go for a cheap, industry standard solution such as Cat 5e cable or future-proof your network by opting for a Cat 7 cable. If you’re looking to connect one switch to another or bypass a router, maybe crossover cables are the solution, or maybe you need a lot of patch cables to connect more devices to your network. In any case, you’ll also want to ensure you’re purchasing the right length of Ethernet cable, and properly addressing any interference concerns. No matter what your networking needs are, eBay is sure to have the category, length, and condition of Ethernet cable to get you connected.
More Related Ethernet Cable Tips
What is the difference between CAT5, CAT5E and CAT6 cable? Most people may be familiar with them. Because they are often used in computer networks, and also can be used to move data in home theatre applications. Category 5 (CAT5), Category 5E (CAT5E) and Category 6 (CAT6) cables are all twisted pair cables, available in solid and stranded varieties. What are their own features? In the following part, we will talk about the main difference between CAT5, CAT5e and CAT6.
CAT5 cable is the most common, and comes in two types—Unshielded Twisted Pair, known as UTP, and Screened Twisted Pair, called SCTP. The SCTP cable has an extra shield to limit outside interference, and is generally only used in Europe. UTP cables are used all over the states and come either solid or stranded. Solid CAT5 cables are stiff and the best choice for long distance transmissions. Stranded CAT5 is bendier and is often used as patch cable. The standard amount a CAT5 cable can handle is 100MHz, with the option for 10 or 100 Mbps Ethernet. A CAT5 cable can also carry more than one signal—such as two phone lines and a single 100BASE-T channel in one cable.
CAT5e is very similar to CAT5,the ‘e’ standing for enhanced. This cable has more ability for data transmission, with the option to transfer data at 1000 Mbps. Cat5e can also be used with Gigabit Ethernet and generally has less near-end crosstalk, or NEXT than standard CAT5 cables. When installing a new system, CAT5e cables are almost always used over CAT5, though most existing installations are still CAT5.
The most sophisticated of the three cables is CAT6. Although it is also comprised of four pieces of twisted pair copper wire, it has a longitudinal separator. This allows the cables to be separated from each other and, in turn, allows not only for an increased data transfer speed, but less crosstalk and double the bandwidth. CAT6 cabling is a good choice for most new systems, especially those that are evolving and might need more options in the future. CAT6 is perfect for 10 Gigabit Ethernet and can work at up to 250 MHz. The really intelligent aspect of CAT6 is that it is compatible with already installed CAT5 and CAT5e cabling.
With the ever-changing landscape of technology, when you are installing a new system, the best choice for an easily adaptable future is CAT6. However, CAT6 is more expensive, and often some companies just don’t need anything quite that sophisticated. If you are just wanting to expand your network a bit, CAT5e is a more cost-effective and the simpler choice. CAT5, though perfectly adequate for many existing systems, will just not be able to keep up with the speed and performance needs of tomorrow.
Category 5 Network Cable
Bandwidth up to 100MHz
Supports 10/100 Ethernet (Ethernet and Fast Ethernet)
Category 5E Network Cable
Bandwidth up to 350MHz
Supports 10/100/1000 Ethernet (Ethernet, Fast Ethernet, and Gigabit Ethernet)
Backwards compatible with CAT5 cable
Reduced crosstalk compared to CAT5
Category 6 Network Cable
Bandwidth up to 550MHz
Supports 10/100/1000 Ethernet (Ethernet, Fast Ethernet, and Gigabit Ethernet)
Backwards compatible with CAT5/CAT5E cable
Reduced crosstalk compared to CAT5/CAT5E
CAT5E supports Gigabit networking, but CAT6 is certified for Gigabit networking and will perform better over longer distances. Keep in mind that your network is only as fast as your slowest component, so unless every piece of your network (routers, cables, etc.) supports Gigabit Ethernet, you will not be able to reach those speeds.
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How to connect 2 routers and 3 switches correctly? It’s a common question for users to set or reset their network. What’s your experience and suggestions about this? One of Cisco champions called Hamza shared his problem of connecting 2 routers and 3 switches. And more Cisco champions discussed it together. Let’s check it. Any idea? Welcome…
The problem is: “I know how to connect a router with two switches and they're able to do successful communication. But If I extend the scenario to two routers and three switches, they don't communicate…
Consider the scenario details in the image
Adam Loveless: My guess would be that you need to configure some routing. Please either post up your sanitized configs or the Packer Tracer file.
Kev Santillan: Hello, you need some form of routing. A router will make its decision based on the information that it has in its own routing table. If Router 1 or Router 0 does not have a route to each remote network, then you will not be able to establish communication. Either use static routes or a routing protocol.
I also noticed that you have the same address (172.16.1.1) for both routers. Is this just a typo?
…Hamza uploaded the pkt file
- Test.pkt.zip (13.3 K)
Kev Santillan (again): The reason why the routes are not learned by each node is because you have assigned a duplicate address (172.16.1.1) to the interfaces that are in the same segment. Change the address of one of the routers to any other address within the 172.16.1.0 /24 subnet and things will work as expected.
Hamza: So basically they should be of the same class in order to work but not the same id i.e the gateway?
Chandan Singh Takuli: Router conencts 2 different networks of any class or classless. If you know a & i know a too why would i ask you. same happens in routers too.
Every router must have all of its interface in different networks and every port must have a unique ip in a single topology or network. so that it can be identified accurately and reached.
Gateway is just like a door of a room. a single network/subnet is like a room. So when you wanna go to another network or room, you need to go through gateway or door in the room.
Gateway ip must be a part/ip of the source network/subnet.
More than this problem
Rick raised his question: to Kev and Chandan: I tried that out-change one of the router interfaces from 172.16.1.1 to 172.16.1.4. But ping from far left hosts still can't reach far right hosts. And for the two hosts in the middle, what default gateway can they use?
Kev Santillan: Hi Rick, ‘I tried that out-change one of the router interfaces from 172.16.1.1 to 172.16.1.4. But ping from far left hosts still can't reach far right hosts.’ I believe modifying either of the addresses in Hamza's file should make things work immediately. Note that he is using /16 for the 172.16.X.X network. Check the mask that you have specified. Otherwise, please share the PT file.
‘And for the two hosts in the middle, what default gateway can they use?’ They can use either of the routers' addresses. If the "middle LAN" uses Router 2's address as the DG and tries to reach non-local networks, it will always pass through Router 2 first before being routed elsewhere. You can also use HSRP to have one dedicated gateway address but the logic will be the same. The active router will be the one to route traffic accordingly.
What’s your idea? Share here…
Discussion from https://learningnetwork.cisco.com/thread/72202?tstart=0
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Learning the networking technology can help you understand the internet better. This is the media of connecting one or more persons with each other. By using internet, we can share our stories, knowledge, opinions and experiences with other people. We also can discuss interesting and hot topics with new friends by internet. Through internet you also can broaden our minds. Well, wow, wow, we know that internet is a network of networks. The main network types: LAN, WAN, PAN, and MAN. Are you confused with these network types? What do they all mean? In this article we will discuss and talk about what the exact LAN, WAN, PAN, and MAN network types are. The key difference is the geographical areas they serve.
LAN (Local Area Network) stands for local area network. It covers, as the name suggests, a local area. This usually includes a local office and they're also pretty common in homes now, thanks to the spread of Wi-Fi.
Whether wired or wireless, nearly all modern LANs are based on Ethernet. That wasn't the case in the 80s and 90s, where a number of standards, including NetBEUI, IPX and token ring and AppleTalk. Thanks in large part to its open technology, Ethernet rules supreme. It's been around since the early 70s and isn't going away anytime soon.
There are two ways to implement Ethernet: twisted-pair cables or wireless. Twisted pair cables plug into switches using RJ-45 connectors, similar to phone jacks. (Remember those?). Cables plug into switches, which can be connected to other networks. A connection to another network is a gateway that goes to another LAN or the Internet.
The other popular Ethernet access method is over Wi-Fi under the IEEE 802.11 standard. Almost all new routers can use the b/g/n standards. IEEE 802.11b and g operate in the 2.4 Ghz spectrum, while n operates in 2.4 and 5 Ghz, allowing for less interference and, thus, better performance. The downsides to wireless are the potential for interference and potential eavesdropping.
WAN (Wide Area Network), in contrast to a LAN, refers to a wide area network. The name is exactly what it sounds like: a network that covers an area wider than a LAN. Beyond that, the definition is less clear. Distances can range from a network connecting multiple buildings on a corporate or college campus to satellite links connecting offices in different countries. The most popular WAN is the one you're using to read this article: the Internet. It's actually a collection of other networks, including other LANs and WANs - hence, the name.
WANs can be wired, using fiber-optic cable, for example, or wireless. A wireless WAN might use microwave or infrared (IR) transmission technology, or even satellite. Laying fiber may make sense when connecting a campus but becomes more expensive when connecting greater distances. To save money, an organization may opt for wireless technology or lease lines from a third party.
Virtual Private Network (VPN)
Another method that has become popular in recent years is the use of a virtual private network, or VPN. It uses the Internet to allow people to log into a network remotely and access its resources, but encrypts the connection to thwart eavesdroppers. If your company sets you up with a VPN, you can access your corporate intranet, file servers or email from home or a coffee shop - just as if you were using it in your office. This makes VPN a popular way to support remote workers, especially in fields where privacy is paramount, such as healthcare. Windows, Mac OS X and many Linux distributions can act as VPN clients’ right out of the box.
Remote desktop virtualization takes this process even further. The entire desktop and applications run on a remote server, and are accessed from a client, which can run on a conventional laptop or even on mobile devices such as tablets or smartphones. This makes virtual desktops great for supporting BYOD (bring your own device) schemes. If a device is lost or stolen, the data is safe because it lives on a central server. Citrix and VMware are the biggest known vendors of virtual desktops.
Personal Area Network (PAN)
PAN stands for personal area network, and again, it's exactly what it sounds like: a network covering a very small area, usually a small room. The best known wireless PAN network technology is Bluetooth, and the most popular wired PAN is USB. You might not think of your wireless headset, your printer or your smartphones as components in a network, but they are definitely talking with each other. Many peripheral devices are actually computers in their own right. Wi-Fi also serves as a PAN technology, since Wi-Fi is also used over a small area.
A MAN (Metropolitan Area Network) (not to be confused with "man pages" in the UNIX and Linux world) connects nodes located in the same metro area. For example, a company located in the San Francisco Bay Area might have its buildings in San Francisco, Oakland and San Jose linked together via a network.
One of the most common ways for organizations to build this kind of network is to use microwave transmission technology. You might have seen a microwave antenna on a TV news van, extended high in the air, beaming video and sound back to the main TV studio. It's also possible to wire buildings together using fiber-optic cable, but as with WANs, most organizations that use wires will lease them from another carrier. Laying cable themselves is quite expensive.
In the past, organizations that had a MAN used asynchronous transfer mode (ATM), FDDI or SMDS networks.
After we have got the main information of these main network types, we find that the concepts are really self-explanatory. We hope these tips and information useful for you to understand the essential internet in our life.
Rs from http://www.techopedia.com/2/29090/networks/lanwanman-an-overview-of-network-types
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This article focuses on another important network model, the Cisco hierarchical network design model. Very different that the OSI model, this model is used as the basis for designing Cisco networks for security and performance. The article provides an overview of the roles and responsibilities of each of the model’s 3 layers.
While the OSI model is concerned with how different systems communicate over networks, the Cisco hierarchical model is a blueprint of types that defines how networks should be designed in layers. Each layer is meant to have its own roles and responsibilities, but the goal is to create a network that delivers high performance, is manageable, and keeps required roles in their place. While this model was designed by Cisco, its use can by all means be adapted to account for the switching and routing equipment of any vendor.
The model is made up of three layers, including Core, Distribution, and Access. The diagram below shows each of these layers relative to one another.
The Core layer of the network would be considered along the same lines as the backbone – high speed and redundant. The Distribution layer would contain intermediate switches and routers, such as those used to route between subnets or VLANs. The Access layer is literally where user’s PCs plug into their local switch, somewhere like an area wiring closet. While this is a simplified view of the network, it provides a general high-level overview.
Getting a little deeper into things, each layer of the model is actually home to multiple roles and responsibilities. Remember that this is a model, and as such not all networks will necessarily look like this – many, especially smaller ones, may not even be close. Instead, think of this model as one that outlines best practices to ensure that the network is reliable, scalable, and meets performance requirements.
Each layer in the model has a general level of responsibility, in terms of what capabilities should be implemented there, and with a particular emphasis on how that layer should perform. Each of the layers is outlined in more detail below.
The responsibility of the core layer is to act as a high-speed switched backbone. Notice that the backbone is expected to switch traffic, and not route it. Routing can severely impact performance, mainly because each frame needs to be recreated as it passes through each router, as we’ll look at a little later in the series. Switching provides much higher performance, mainly because a frame can travel across the backbone without needing to be recreated at each switch. That’s not to say that the frame isn’t inspected at every switch (it will be to varying degrees), but everything stays at OSI layers 1 and 2 instead of having to be considered at Layer 3. The Core layer is usually comprised of a relatively small number of high-end switches. Growth should not add devices, but rather replace devices with higher-speed equipment as necessary.
The Core Layer is also responsible for providing a degree of redundancy by providing multiple paths. That is, you want to be sure that even if a backbone link goes down, another path exists over which frames can travel. We’ll consider this in a diagram shortly.
In general, you want to be sure that the only traffic that moves across the backbone is that which is moving between different Distribution-layer devices. A design that moves traffic over the Core layer when it isn’t necessary will not provide the best performance. To that end, the core should also never be used to implement traffic filters such as access lists – these should be implement at other layers instead.
To summarize, the Core Layer should:
- Be used to provide high-speed switching.
- Provide reliability and fault tolerance.
- Grow by using faster, and not more, equipment.
- Never implement performance-decreasing elements such as access lists.
The distribution layer acts as an intermediary between the Core and Access layers, and is usually where the routing functions (and more) on a well-designed network are found. An example of the type of interconnection here includes those between different types of media such as Ethernet and Token Ring. The distribution layer is also where policies are usually implemented using Access Lists.
To get a feel for the function of the distribution layer, remember that a great deal of routing will usually happen on a network. Clients on one subnet may need to talk to servers on another. In some cases this traffic is localized, such as with departmental file or database servers. However, there are often servers that need to be accessed by many subnets even within a given location, such as mail servers. The distribution layer would be responsible for this routing function. In all, this layer serves a number of purposes including the implementation of
- Security, in the form of Access Lists and filtering.
- A boundary for route aggregation and summarization (for example, many subnets can be hidden behind a single routing table entry, making these entries smaller, and routing more efficient).
- Broadcast domains. A broadcast domain is a layer 2 concept that defines how far a broadcast will travel on a given network. By default, routers usually do not pass broadcasts, acting as the demarcation point between broadcast domains.
- Routing. Almost all routing is done at this layer, which keeps it away from the backbone. This also acts as the intermediate point between where static and dynamic routing are used on the network.
The Access Layer acts as the point as which end stations connect to the network, usually by plugging into Layer 2 switches or hubs. As such, this layer is usually used to define network collision domains. The Access layer is also sometimes used to define additional network security policies and filtering if necessary.
How it fits together
The diagram below shows how a typical network might be configured to account for the Cisco hierarchical network design model. Remember that the Core layer switches might be geographically dispersed, and that the distribution layer routers might be connected to the core via a WAN link of similar.
Rs from http://archive.networknewz.com/2004/0206.html
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Subnets and VLANs are two concepts that go hand-in-hand.
Best networking practice is a one-to-one relationship between VLANs and subnets.
Here are the top 10 things you should know about these critical components of Converged Plantwide Ethernet (CPwE) Design and Implementation:
- A Layer-2 network also refers to a subnet, broadcast domain and a virtual LAN (VLAN). Best practice is a 1:1:1 relationship between subnets, broadcast domains and VLANs. The Layer-2 network infrastructure devices in the Cell/Area zone are predominantly access switches.
- Layer-3 switches or routers are used in manufacturing environments. Layer-3 switches or routers forward information between different VLANs or subnets. They use information in the IP header (Layer 3) to do so. Regardless of the specific layer being connected, switches provide Industrial Automation Control System (IACS) networks with many of the safeguards realized by the natural separation inherent in existing IACS-optimized networks. Some switches promoted as Layer 2 switches also support limited routing capabilities, like static routing.
- Devices and controllers configured for multicast delivery need to be located within the same Cell/Area IACS network because these packets cannot be routed, meaning that any router will drop the packet before forwarding it outside the subnet/VLAN. Devices and controllers configured for unicast delivery, Implicit I/O or explicit messaging do not need to be within the same Cell/Area zone because that communication is routable.
- Logical segmentation is the process of outlining which endpoints need to be in the same LAN. Segmentation is a key consideration for a Cell/Area IACS network. Segmentation is important to help manage the real-time communication properties of the network while supporting the requirements defined by the network traffic flows. Security is also an important consideration in making segmentation decisions. A security policy may call for limiting access of plant floor personnel (such as a vendor or contractor) to certain areas of the plant floor (such as a functional area). Segmenting these areas into distinct subnets and VLANs greatly assists in the application of these types of security considerations.
- Network developers should strive to design smaller LANs or VLANs, while recognizing that the traffic patterns of an IACS may make this difficult if routing is required.
- Use VLANs in addition to any physical segmentation, and connect all Cell/Area LANs to Layer-3 distribution switches to maintain connectivity.
- Trunks are also an important concept when deploying VLANs. The inter-switch connections in a Layer-2 network deploying VLANs are referred to and configured as trunks because they carry traffic for multiple VLANs. The relevant standard is IEEE 802.1Q, which specifies VLAN tagging to carry multiple VLANs on Ethernet links between switches. IEEE 802.1Q is the prevalent and most often used standard.
- Management VLANs are also an important consideration when establishing a VLAN concept. In the IT and enterprise network, management VLANs are commonly used to access the network and IT infrastructure, separate from the data VLANs. If IT is involved in managing the IACS network, they may want to establish management VLANs on which only the network infrastructure has IP addresses.
- Two important considerations in designing a VLAN network are the use of VLAN 1 and the native VLAN. The native VLAN is the VLAN to which a port returns when it is not trunking. VLAN 1 is the default native VLAN on trunk ports on Cisco-based switches and therefore may use by a number of network infrastructure protocols.
- Define IACS devices to use a specific VLAN other than the native VLAN and VLAN 1; do not use VLAN 1 for any purpose. Some security threats assume that VLAN 1 is the default VLAN for data and/or management traffic and may target VLAN 1 in their attacks.
Article Source from http://www.industrial-ip.org/en/industrial-ip/convergence/vlans-and-subnets-10-things-you-need-to-know
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Cisco is always focusing on making network devices smarter and providing more intelligent and safer networking solutions for customers.
One of typical examples is Cisco Adaptive Security Appliance (ASA). When it encounters a critical unrecoverable error condition, it reloads itself and then automatically sends in the error report. This report is analyzed by Cisco and compared against all known issues. If Cisco has seen this issue before, we will:
- Alert the customer via e-mail that their device encountered a problem
- Include the bug ID and Headline of the problem the device experienced
- Indicate what versions contain a fix to this issue
This provides you with everything you need to know about the problem.
How is that for Smart?
The Cisco ASA also detects other error conditions, these (i.e.: fan failures, interface failures, other environmental alerts, etc…) and securely reports those back to Cisco. For critical events, it will automatically open a TAC case and start working on the problem. That may be initiating an RMA and shipping the part on-site, or it could be that a TAC engineer will call you to alert you to the problem and what the next steps are. For non-critical events, you will receive an e-mail to alert you to the problem and include guidance on the next steps.
In addition to this, we are investing in big data initiatives to mine the data being sent in and obtain insights on how we can better improve our software quality, or to quickly be alerted to any critical issue affecting multiple customers-all in an automated fashion.
Reference From: https://supportforums.cisco.com/docs/DOC-35118
More networking topics you can visit: http://blog.router-switch.com/category/networking-2/
For any network administrator, it is a necessary to know how to properly use logging. The Cisco IOS offers a great many options for logging. To help you know them well, we will discuss how to configure logging, how to view the log and its status, and list three common errors when it comes to logging.
The logging command in Global Configuration Mode and the show logging command in Privileged Mode are two simple but powerful tools to configure and show all Cisco IOS logging options. Let's take a closer look.
Configure logging in the Cisco IOS
When configuring logging, the most important command to know is the logging command, used when in Global Configuration Mode. Here's an example of this command and its options.
In order to help you know these options in a good way, let’s look at the most common ones.
You can configure the router to send buffered logging of its events to the memory. (Rebooting the router will lose all events stored in the buffered log.) Here's an example:
Router(config)# logging buffered 16384
You can also send the router's events to a syslog server. This is an external server running on your network. Most likely, the syslog server is running on a Linux or Windows server. Because it's external to the router, there's an added benefit: It preserves events even if the router loses power. A syslog server also provides for centralized logging for all network devices.
To configure syslog logging, all you need to do is use the logging command and the hostname or IP address of the syslog server. So, to configure your Cisco device to use a syslog server, use the following command:
Router(config)# logging 10.1.1.1
The Cisco IOS enables logging to the console, monitor, and syslog by default. But there's a catch: There's no syslog host configured, so that output goes nowhere.
There are eight different logging levels.
The default level for console, monitor, and syslog is debugging. The logging on command is the default. To disable all logging, use the no logging on command.
By default, the router logs anything at the level of debugging and greater. That means that logging occurs from level 7 (debugging) up to level 0 (emergencies). If you want to par down what the system logs, use something like the logging console notifications command.
In addition, the router doesn't enable logging to the system buffer by default. That's why you must use the logging buffered command to enable it.
View the status of logging and the logging itself
To view the status of your logging as well as the local buffered log, use the show loggingcommand. Here's an example:
Note that this router has enabled syslog logging and is sending it to host 10.1.1.1. In addition, console logging is at the debugging level, and the setting for local buffered logging is 10,000,000 bytes.
Three common logging errors
Logging can be frustrating at times. To help prevent some of that frustration, let's look at three common errors.
Not setting the terminal to monitor logging
If you Telnet into a router and can't see some of the logging you're expecting, check to see if you've set your terminal to monitor the logging. You can enable this with the terminal monitor command. To disable it, use the terminal no monitor command.
To determine whether you've enabled monitoring, use the show terminal command, and look for the following:
Capabilities: Receives Logging Output
If you see this, you're monitoring logging output. If it returns none for capabilities, then the monitoring is off.
Using the incorrect logging level
If you can't see logging output, you should also check whether you've set the level correctly. For example, if you've set the console logging to emergencies but you're running debugging, you won't see any debugging output on the console.
To determine the set level, use the show logging command. Keep in mind that you need to set the level to a higher number to see all levels below it. For example, setting logging at debugging shows you every other level.
In addition, make sure you match the type of logging that you want to see with the level you're configuring. If you configure monitor logging to debug but you're on the console and you've set it to informational, you won't see the debug output on the console.
Displaying the incorrect time and date in logs
You may see log messages that don't exhibit the correct date and time. There are a variety of options to control the date and time that appear on logging output (either to the screen or to the buffer). To control this, use the following command:
Router(config)# service timestamps debug ?
datetime Timestamp with date and time
uptime Timestamp with system uptime
More Notes: Remember that many problems require some kind of historical log to help find a solution. That's why it's important to make sure you've properly configured logging so you can use your logs to see the past.
Reference from http://www.techrepublic.com/
Cisco Aironet 36021 AP and Ubiquiti's UniFi AP are part of the so-called “wave 1” phase of 802.11ac standard.
These access points (APs) are theoretically capable of reaching data rate of up to 1. 3 Gigabits per second but actual maximum throughput speeds achieved during a test conducted by technology publication Computerworld.com just reached the 360 to 380 Megabits per second range.
Here is how the two access points fared against each other in terms of speed, features and performance:
Cisco Aironet 36021 AP–This access point came with an 802.1ac module. A Cisco 2504 Wireless LAN controller was use for the test.
The Aironet 36021 comes with two integrated 2.Ghz/5GHz dual radios. The 802.1ac module adds ass a 5-GHz radio supporting three spatial streams.
The AP supports the standard Control and Provisioning of Wireless Access Points Protocol (CAPWAP) and broadcasting up to 16 SSIDs. The maximum transmit power for both integrated dual band radios is 23 dBm and 22dBm for the 802.11ac module.
The Aironet 36021 AP is worth $1,495. Its accompanying 802.11ac model is $500.
Ubiquiti UniFi AC-The $299 Ubiquiti AP came with UniFi Controller software to manage the AP.
This access point has a 2.4GHz radio and 5GHz radio with three spatial streams that support up to four BSSIDs per radio. The radios maximum transmit power is 28 dBm.
This AP has a similar physical dimension as the Cisco unit but weighs about a pound more. It is straightforward to setup and configure just like the Aironet. The Ubiquiti AP has a user-friendly interface.
While the unit does not allow user to configure many settings it allows application of general wireless, network and guest settings across multiple UniFi Aps. User can also place access points on an uploaded map and view stats information on AP and client usage.
Testers found the Cisco AP performed four per cent to 22 per cent better than the Ubiquiti AP in the throughput test. The Cisco AP is recommended for larger enterprise networks.
They concluded that the Ubiquiti AP lacked advanced enterprise settings but is easier to setup and more ideal for small to midsize networks
---News from http://www.itworldcanada.com
More Related to Cisco Wireless Aps:
As service providers continue their IP network convergence, they also need to establish a business strategy that can provide a solid return on their next-generation network investment. Creating a network transformation plan is an essential part of the process that will help service providers increase the efficiency and flexibility of their next-generation networks and services while reducing operations expense (opex).
This Telecom Insights guide looks at what service providers need to know about deploying a converged network architecture that focuses on offering differentiated services that capitalize on their infrastructure and unique customer knowledge and how providers should go about building a solid network transformation plan that will result in the necessary ROI to compete and thrive.
In this series:
- A new vision for telecom network transformation
- Five steps to a next-gen network transformation plan
- Three mega-trends revolutionize telecom
A new vision for telecom network transformation
Much bigger than problems created by an economic downturn, network operators worldwide are facing much more pressure from longer-term erosion in the value of their stock-in-trade: transport bits.
Because business planners need to focus first on profit and revenue growth, today's fundamental market shifts mean that shorter-term planning will have to encompass a different vision of transformation and a different model of monetizing network investment.
The telecom services market is increasingly like a supermarket, with supermarket-like principles. Some services, like certain grocery items, will always be in demand but don't have much feature differentiation. These will become commodities in terms of price but will sustain the foundation of revenues and create customer loyalty. Other services, such as premium items in a store, will produce less revenue but command strong margins and boost profits. The transformation of the network marketplace to this model is the most significant goal for the industry.
Turning transformation on its head
Supporting this kind of transformation is still a hazy notion that could be called the Next-Generation Networks Services Architecture, or NGNSA. This architecture harmonizes the key components of next-generation network transformation:
- Service feature orchestration and syndication through developer partners, over-the-top partners, and traditional service provider partners.
- Business and operations management tools that are "service-focused" to align them with new directions in service creation and support a much higher level of automation of service lifecycle processes.
- Network infrastructure that can be quickly adapted to the traffic patterns and service-level agreement (SLA) needs of the widest variety of services, and tight coupling to the service layer of the network so network operators can differentiate their services from over-the-top solutions. This includes service delivery platforms (SDPs) for computing/software service components and network equipment for connection and transport.
The primary reason NGNSA notions are still fuzzy is the fact that activities are spread across a number of standards processes. While there are active liaisons between the bodies, standards are not moving in synchrony or even particularly quickly. As a result, network operators are looking increasingly to vendors for leadership in these areas and expecting those vendors to support the standards as they develop rather than waiting for them.
Nearly all major network operators worldwide report that they expect to buy into some vendor vision for integrated NGN services in the next year. For those operators, the choice of what approach to take is likely to be set by the priority they place on the three major NGNSA elements.
Complete solutions will drive partnerships
Of the three areas, the second (service operations and management) is probably the most developed in a standards sense, and thus network operators probably understand the positions of their vendor partners and have a good sense of convergence on standards approaches. But not every major equipment vendor has a service management strategy, and pressure to provide a complete solution is likely to create partnerships between management and networking vendors.
Service feature orchestration and third-party partner access to service elements for composition of retail services are likely to be the major focus of network operators in the near term. This area has not been active in the standards-setting sense for as long because the requirements of the space are less understood.
A number of announcements or commitments by equipment vendors in 2008 support the componentization, syndication and composition of services. And the architectures are only starting to emerge. The best approach here may be the most important single factor in creating NGNSA partnerships in the next two years or more.
Service-layer technology must create ROI
For the longer term, the last issue cannot be neglected. Service-layer technology that simply sits on top of connection/transport infrastructure ("anything over the Internet") empowers not only network operators but also over-the-top players. What network operators need and want is a way of creating value from their networks in the form of something linked with, but stepping beyond, the movement of bits. Little has been done in an organized industry sense to create specific service-layer partnership with the network layer. This partnership would provide a special benefit to those who build and own the networks. Thus it would justify network infrastructure investment more effectively by sustaining a higher return on investment (ROI).
ROI has been important for network operators for years, but the importance of ROI is magnified by a combination of economic uncertainty and increased pressure to evolve off the older TDM voice platforms in favor of IP-based services, including voice. 4G technology is based on IP voice, and fixed mobile convergence (FMC) is facilitated if voice technology in both wireline and wireless is based on VoIP. Major tier 1 operators are already announcing serious VoIP offerings, and this will put additional pressure on service-layer deployment because the move is almost certain to lower revenue per call-minute over time.
The role of IMS in the next-generation network
The fact that voice may be a driver for near-term change makes the IP multimedia subsystem (IMS) decision particularly important for operators. IMS is the approved and standardized way to manage mobile VoIP, FMC and non-voice mobile services. IMS is at least a candidate for supporting other NGN services such as video. Here again, standards may not keep pace with market requirements, and network operators may have to work with vendors prepared to take leading-edge positions on harmonizing IMS with service models beyond those involving SIP calling.
The ITU has suggested, in its NGN material, that IMS is one of several elements in what we have called here an NGNSA. But the precise role of IMS in that mix is not defined, nor are the other elements that would coexist with IMS. The vision of IMS's role in NGNSA may be the most critical of all in the near term because of the pressure to evolve voice services.
Network operators plan over a very long cycle--typically about seven years. That means that economic disturbances in the field are less a factor than they would be to industries with shorter capital cycles. Long planning cycles also mean that network operators require a very high degree of confidence in every step of their solution to evolving service needs and opportunities. That requirement is likely to generate new relationships and new levels of cooperation with vendors in the coming years.
Five steps to a next-gen network transformation plan
If transformation has a business goal and convergence a technical goal, then surely one of the challenges that face service providers today is how to navigate a commitment to both at the same time.
The problem is only complicated by the fact that transformation, unlike convergence, has no established formula or timetable. It's hard to get management support for something that, except for the goal itself, seems rather hazy.
The goal of transformation is to define a business strategy that creates sustainable revenues and profits from next-generation network (NGN) investments. Meeting that goal may require different specific technologies and services, but it can be accomplished with a general program that has some defined elements and timing recommendations. It is also important to address a few considerations or recommendations of what not to do, because some steps that are often taken are rarely successful.
Five steps to creating an NGN transformation plan
1. Picking a specific NGN service target set: This is the most problematic of all transformation steps. The most significant difference between the service environment of the past and that of the present is the short-term nature of buyer commitments to service paradigms. Basic voice and connectivity services are long-lived, in large part because they are so basic. As operators attempt to monetize NGN services, they must contend with the fact that the most valuable services to an operator are also those most valuable to service consumers, and this value proposition will change over time.
If committing to an inflexible NGN service strategy is exactly the wrong move, the best move is to create a service-layer architecture with the greatest flexibility possible -- both in terms of the way it can compose and combine service features and in the delivery options (wireless, wireline, computer, TV, phone, etc.) available. In fact, the difference between an IP network and an NGN is in the service-layer flexibility. IP alone simply creates a connectivity base that will be exploited by others but may not be profitable. NGNs must ensure the profit by providing services in a flexible way, not just transporting their traffic.
2. Restructure network, operations and business management systems around services, not technologies. In the second transformation step, the NGN service set will differ from the old set in that it will be made up of shorter-contract-period services with much wider markets. This means that inefficiency in service operations cannot be tolerated, or the costs will mount to swamp the budget. There are standards processes under way to guide this resetting of operations priorities, and many vendors already have tools and plans to support the switch. Services are the product of service providers, and management systems must reflect that reality.
3. Classify service opportunities at the high level. There is a taxonomy of service opportunities, starting with the basic classification of the customer (residential, enterprise, small business) and the nature of the value proposition the service will have for the customer (communication, data exchange, collaboration, hosting, software and computer outsourcing, etc.). For each opportunity element in the structure, there will be a total addressable market and a likely market penetration curve, and these can be used to set service opportunity priorities -- but not yet.
4. Identify the infrastructure implications of each of the opportunities. The goal here is not to plan out every piece of equipment or technology direction but rather to group the opportunities according to the type of infrastructure investment required to support them so that co-dependencies can be identified. In terms of an NGN transformation plan, the right answer will probably come by picking the opportunity group that has the best relationship between cost of infrastructure and benefit in terms of opportunity value.
5. Implement and execute a project to create an effective NGN transformation plan.The final step is a project to execute in the direction that is identified by the last step listed above. At the same time, the incremental steps involved in addressing other related opportunity groups should be explored to develop a plan for later investment and service deployment.
Projected timeline for an NGN transformation project
Most service providers have the information needed to support this sequence. If that is the case, operator experience seems to suggest that a task to complete the first three steps would require approximately eight months, assuming that work already done could not be leveraged. Service-layer deployments generally require about that same time for initial deployments, and so it may be that the operations processes in step 2 will be the inhibiting factor in preparing a quick response. This suggests that it is highly advisable that operations restructuring be given a high priority.
Every NGN program will be different, and every operator will have completed some of the tasks associated with each of the steps outlined here. An inventory of activities is often very useful in ensuring that nothing that has already been done is wasted, and this will also produce a faster path to NGN success.
Three mega-trends revolutionize telecom
Upcoming telecom changes are nothing short of revolutionary, or at least evolutionary, as trends emerge to create a single business model ecosystem out of telecom and the Web, content players and service providers find a workable balance of power, and cloud computing and social networking features gain in importance. Here's a look at the three main trends that will change telecom for the long haul.
1. An emerging online ecosystem joins telecom and the Web into a single business model
In December 2008, Alcatel-Lucent announced a company strategy based on creating the tools for this new ecosystem. Cisco CEO John Chambers had similar comments about binding the tools of the Web into a single, cohesive development framework.
In addition, articles about how Google was looking for a "fast lane" from access providers to speed its content to users seemed to make it clear that the old face-off between the over-the-top players and the telecoms might be ending. We've had years of "over-the-top" versus the carriers, and now we're heading for a future where the distinction will become very fuzzy indeed -- not through mergers and acquisitions but through cooperation.
For three or four years, telecoms and Web companies alike have been working to gain support from application developers to enrich their services. The iPhone and Android models were compelling because they generated a cottage industry that has driven the core product and service set to much greater utility, as well as greater adoption rates and revenue generation. The problem is that while everybody seems to want to support developers, everyone supports them differently.
No one has solved the question of how all these cooperative players manage to combine their efforts to create something stable, easily supported and capable of generating revenue for all through cooperative settlement. Standards have been marking time in this area, and now it looks as if equipment vendors are stepping in to create the framework for the new ecosystem. Why? Because capex is usually pegged to revenue, so if you can't help your carrier customers raise their top line, their spending will languish and so will vendor profits.
Service providers tried to solve this problem of cooperative ecosystem-building with standards, but they moved too slowly. They then started to pressure their equipment vendors to come up with a solution, and the Alcatel-Lucent and Cisco announcements are the result. There will be others; and it will be all about "service mashups."
2. A CDN/cloud computing model emerges for settlement for online services
This is why the new ecosystem is suddenly developing. For decades, the Internet has suffered from a basic problem of lack of settlement among the providers. Everyone pays for access to their ISP, but nobody pays for transit. Where there's no revenue, there's no investment.
On the other hand, content providers are happy to pay for content delivery network (CDN)caching, and Software as a Service (SaaS) providers are eager to find good cloud computing resources. The access carriers are putting money there, and these new resources link not to the Internet core but to the access networks. Telecoms worldwide have seen the opportunity to create a link between investment and revenue, and that new link threatens the whole legacy model of the Internet. It's bringing the Web guys to the table.
If every piece of content and every application were cached or hosted in metro centers, there would be no core traffic on the Internet at all. That extreme isn't likely, but what's certain is that the valuable stuff is migrating to the metro area. That forces the big players like Google to transport their own content via fiber to each access provider, which further bypasses the old Internet peering model.
You can't create a new ecosystem without having the pressure of the old one breaking, and that's what's happening. In the new ecosystem, content and application players will join with search and portal companies and telecoms to fight out a new balance of power.
The most significant winners will be the content/application giants, because getting commercially valuable content via a network connection is the stock in trade of the future.
3. Integrating social network features and relationship knowledge into communications is a trend in the making.
Yahoo launched an advanced email system that illustrates the value of relationship-managed communications, and this new notion will be incorporated into an expanding notion of presence as the central framework for communications and collaboration.
Presence-centered personal communication is the most "tactical" of the major trends because it will have an immediate impact on a number of emerging technical and product trends. Collaboration and telepresence both work better, and justify more investment, if they're mediated through social-network-like frameworks. This is likely to be one of Cisco's major areas of focus in harmonizing all of the Web 2.0 APIs into a new ecosystem. It's also likely to be a focus for unified communications and even things like IMS, femtocells and fixed-mobile convergence (FMC).
What technologies will benefit?
The technologies that will benefit from these major trends are:
- Fiber access, including FTTH and FTTN, because access providers will continue to fight speed wars with one another as they look to leverage their role in the new ecosystem.
- Metro Ethernet and optics, since all of the recent bandwidth created will be within metro areas. Look for new interest in hybrid Ethernet/optics products as well.
- Femtocells and FMC, which will probably benefit IMS. Mobile service competition and the need to integrate mobile and wireline features will be a big boost to this area.
- Operations software, particularly service management, abstraction, componentization, composition and third-party access via APIs.
The broadest impact of the trend on vendors will be promoting a more integrated product strategy that offers telecoms a link from revenue to investment. For many, this will involve partnerships supplemented by selective development or acquisitions that are intended to make each vendor's offerings unique and thus more likely to be accepted by buyers.