Different Classes of IP Address

IP Address Classes and Structure

When the IEEE committee sat down to sort out the range of numbers that were going to be used by all computers, they came out with 5 different ranges or, as we call them, "Classes" of IP Addresses and when someone applies for IP Addresses they are given a certain range within a specific "Class" depending on the size of their network.

To keep things as simple as possible, let's first have a look at the 5 different Classes:






In the above table, you can see the 5 Classes. Our first Class is A and our last is E. The first 3 classes ( A, B and C) are used to identify workstations, routers, switches and other devices whereas the last 2 Classes ( D and E) are reserved for special use.

As you would already know an IP Address consists of 32 Bits, which means it's 4 bytes long. The first octec (first 8 Bits or first byte) of an IP Address is enough for us to determine the Class to which it belongs. And, depending on the Class to which the IP Address belongs, we can determine which portion of the IP Address is the Network ID and which is the Node ID.

For example, if I told you that the first octec of an IP Address is "168" then, using the above table, you would notice that it falls within the 128-191 range, which makes it a Class B IP Address.

Understanding the Classes

We are now going to have a closer look at the 5 Classes. If you remember earlier I mentioned that companies are assigned different IP ranges within these classes, depending on the size of their network. For instance, if a company required 1000 IP Addresses it would probably be assigned a range that falls within a Class B network rather than a Class A or C.

The Class A IP Addresses were designed for large networks, Class B for medium size networks and Class C for smaller networks.

Ethernet Cables

Cat 1: Previously used for POTS telephone communications, ISDN and doorbell wiring.

Cat 2: Previously was frequently used on 4 Mbit/s token ring networks.

Cat 3: used for data networks using frequencies up to 16 MHz. Historically popular for 10 Mbit/s Ethernet networks.

Cat 4: Defined up to 20 MHz, and was frequently used on 16 Mbit/s token ring networks.

Cat 5: Defined up to 100 MHz, and was frequently used on 100 Mbit/s Ethernet networks. May be unsuitable for 1000BASE-T gigabit ethernet.Category 5 cable is a currently outdated standard that provides support for up to 100Mhz operation. It can be used for 10/100 Ethernet without worry, however for longer runs of 1000MbE it is recomended to use Cat. 5e or higher.

Cat 5e: Defined up to 100 MHz, and is frequently used for both 100 Mbit/s and 1000BASE-T Gigabit Ethernet networks. Category 5e cable provides support for frequencies up to 100Mhz. Cat. 5e generally provides the best price for performance, however for future proofing Cat. 6 or higher might be a better choice as it usually does not cost much more.

Cat 6: Defined up to 250 MHz, more than double category 5 and 5e. Category 6 is defined up to a frequency of 250Mhz. Allowing 10/100/1000 use with up to 100 meter cable length, along with 10GbE over shorter distances.

Cat 6a: Defined up to 500 MHz, double that of category 6. Suitable for 10GBase-T. It allows up to 10GbE with a length up to 100m.

Cat 7: Defined up to 600 MHz. This standard specifies four individually-shielded pairs (STP) inside an overall shield. Category 7 is the informal name for "Class F" cabling defined by a different standards body than Cat. 6a and lower. It supports frequencies up to 600Mhz and may support the upcoming 100GbE standard.

Cat 7a: Category 7a is an upcoming standard that allows frequencies up to 1000Mhz. Supported Ethernet bandwidths have not been defined.

JUNIPER NETWORKS: Routers

Juniper Networks, Inc. (NASDAQ: JNPR) is an information technology and computer networking products multinational company, founded in 1996. It is headquartered in Sunnyvale, California, USA. The company designs and sells high-performance Internet Protocol network products and services. Juniper's products include T-series, M-series, E-series, MX-series, and J-series families of routers, EX-series Ethernet switches, WX-series WAN optimization devices, and SRC Session and Resource Control appliances. JUNOS , Juniper's network operating system runs on most of the Juniper products. In 2009, Juniper made its debut on Fortune Magazine's 100 Best Companies to Work for. Juniper ranked 4 in Fortune Magazine's World's Most Admired Companies list in Networking Communications category in 2009.

Canopy Antenna

A typical Canopy setup consists of a cluster of up to 6 co-located standard access points, each with a 60 degree horizontal beamwidth antenna, to achieve 360 degree coverage. The most commonly used APs are now available in 120, 180, or even 360 degrees for site-based coverage, thus decreasing the need for so many APs on a tower. Also included would be one or more backhauls or otherwise out-of-band links (to carry data to/from other network occasions) and a Cluster Management Module (CMM) to provide power and synchronization to each Canopy AP or Backhaul Module(BM).

Customers of the system receive service through subscriber modules (SMs) aimed towards the AP. The SMs should be mounted on the tall point of a building to get a reliable connection else Fresnel zone obstruction will weaken the signal. Under ideal operating conditions connections at distances up to 3.5 miles can be achieved using equipment with integrated antennas. Network operators can opt to install reflector dishes or Stinger antennas, or to use Canopy models that accept external antennas at one or both ends of the link to increase coverage distance.

Most Canopy equipment receives its power using Power over Ethernet, however, none of its standards comply with IEEE 802.3af.

In general, the 900 MHz version is more effective for use in outlying areas because of its ability to penetrate through trees. However, it requires careful installation due to the easy propagation of interference on that band. Other frequencies currently available are the 2.4Ghz, 5.2Ghz, 5.4Ghz, and 5.7Ghz versions.

SWITCH vs ROUTER

SWITCH

ROUTER

A router is a more sophisticated network device than either a switch or a hub. Like hubs and switches, network routers are typically small, box-like pieces of equipment that multiple computers can connect to. Each features a number of "ports" the front or back that provide the connection points for these computers, a connection for electric power, and a number of LED lights to display device status. While routers, hubs and switches all share similiar physical appearance, routers differ substantially in their inner workings.
Traditional routers are designed to join multiple area networks (LANs and WANs). On the Internet or on a large corporate network, for example, routers serve as intermediate destinations for network traffic. These routers receive TCP/IP packets, look inside each packet to identify the source and target IP addresses, then forward these packets as needed to ensure the data reaches its final destination.
Routers for home networks (often called broadband routers) also can join multiple networks. These routers are designed specifically to join the home (LAN) to the Internet (WAN) for the purpose of Internet connection sharing. In contrast, neither hubs nor switches are capable of joining multiple networks or sharing an Internet connection. A home network with only hubs and switches must designate one computer as the gateway to the Internet, and that device must possess two network adapters for sharing, one for the home LAN and one for the Internet WAN. With a router, all home computers connect to the router equally, and it performs the equivalent gateway functions.
Additionally, broadband routers contain several features beyond those of traditional routers. Broadband routers provide DHCP server and proxy support, for example. Most of these routers also offer integrated firewalls. Finally, wired Ethernet broadband routers typically incorporate a built-in Ethernet switch. These routers allow several hubs or switches to be connected to them, as a means to expand the local network to accomodate more Ethernet devices.
In home networking, hubs and switches technically exist only for wired networks. Wi-Fi wireless routers incorporate a built-in access point that is roughly equivalent to a wired switch.

Passive Network Components

PATCH PANEL

A patch panel or patch bay is a panel, typically rackmounted, that houses cable connections. One typically shorter patch cable will plug into the front side, whereas the back holds the connection of a much longer and more permanent cable. The assembly of hardware is arranged so that a number of circuits, usually of the same or similar type, appear on jacks for monitoring, interconnecting, and testing circuits in a convenient, flexible manner.

FRONT VIEW

BACK VIEW

REGISTERED JACK

A registered jack (RJ) is a standardized physical network interface — both jack construction and wiring pattern — for connecting telecommunications or data equipment to a service provided by a local exchange carrier or long distance carrier. The standard designs for these connectors and their wiring are named RJ11, RJ14, RJ21, RJ48, etc. Many of these interface standards are commonly used in North America, though some interfaces are used world-wide.

The physical connectors that registered jacks use are mainly of the modular connector and 50-pin miniature ribbon connector types. For example, RJ11 uses a 6 position 4 conductor (6P4C) modular plug and jack, while RJ21 uses a 50-pin miniature ribbon connector.

RJ - 45

MODULAR JACK

Modular jack connectors, a cornerstone of communications technology, have been used in the telecommunications and ethernet industry for many years. The main reasons for this are the simplicity and reliability of these products. Whether integrated in a simple telephone system, or in a gigabit application, “mod. jacks” represent the standard for network connections. Mod. jacks can be obtained in many different versions. Increasing data rates and space-saving requirements are driving increasing requests for these connectors with integrated filter components.

MAC Addres Vs IP Addres

MAC Addres Vs IP Addres
-Historically each adapter card has a physical address (MAC address), which
is used to identify the interface for transmission. This is a flat address,
where each manufacturer is assigned a fixed prefix, which in turn ensures
no two adaptor cards have the same address.
-IP address is designed as a logical address primarily for routing. This is a
hierarchical address, which is divided into a subnet part (network address)
and a host ID within the network. These two parts is combined to a single IP
address.
-Destination address is used to determine the route by table lookup, i.e.,
determine the next hop to forward a packet or more precisely the outgoing
interface within a router or host.
-Recall the Internet is a packet switched network, the packet is stored and
forwarded hop by hop. For the actual hop by hop transmission, the next hop
MAC address is needed to form the link level frame.
-Address Resolution Protocol or ARP is used to translate an target IP
address into a target MAC address in a local area network. The key feature
is to take advantage of the broadcast nature in the local area network. In
case this is a point-to-point connection, a node will directly request the MAC
address of the other end node.


Random Access Protocols
-The most common medium access protocols used in local area networks are
random access protocols, in particular CSMA/CD (Ethernet).
-Slotted ALOHA protocol is one of the first randomaccess protocols designed,
where in each slot a node with a packet will transmit with a probability p.
The simple performance study on Slide 5-19 shows that the maximum
utilization is about 37%.
-CDMA/CD protocol improves over the ALOHA in two aspects, 1) it listen the
channel (Carrier Sense) before transmission, 2) it continue monitoring the
channel after transmission, when there is a collision detected, it will abort
the transmission.
-Assuming the maximum distance between two nodes in the Ethernet is D,
speed of light is R, frame length is L and transmission rate (link bandwidth
is B). The maximum amount of time that a node has to wait after a
transmission is 2D/R (a roundtrip delay). For CSMA/CD protocol to work, it
usually requires that L/B > 2D/R.
-Token Ring relies on the passing of token, in which only the node holding
the Token (a special packet) has the right to transmit. If the ring latency is
D (the propagation delay around the ring), packet size is L, link bandwidth
is B, and there are N nodes on the Ring (equally spaced out). Then the
maximum utilization is achieved when all nodes are having packets to
transmit, i.e., (NL/B)/(NL/B)+D), since there is D/N amount of time for
passing the token between each node (overhead).


Switch and Hub
-Hub is a repeater and it copies incoming packets and sends out to all other
ports with no buffering. So a hub simply extends the distance of a local area
network, which is still under one broadcast domain. More nodes the
network has, more likely there will be collision under CDMA/CD protocol.
-Switch can do intelligent filtering based on the destination MAC address. It
maintain a switch table, when a packet comes, it check whether the
destination MAC address is in the table to see if it can directly forward the
packet to one single outgoing port. If there is entry in the table, it simply
forward to all outgoing ports except the one it receives the packet (exactly
like a hub). See Slide 5-50.
-A switch has self-learning capability, as it can record the interface that it
receives a packet, by checking the source MAC address, it can build a record
in the switch table, record (MAC address, Interface, TTL). Noticing for this
to work, it mandates that a packet can not arrives from more than one
incoming port, that is the topology must be a tree (with no loop).

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Francis Louie Gamayon
flgamayon.blogspot.com