10 Hot Skills for 2009 1. Business Skills Employment surveys have been telling us for a number of years that IT pros must possess business skills as well as technical expertise, and in a down economy IT folks who understand the business could be considered more valuable than those who don’t. A survey by CompTIA of 215,085 IT pros found that employers valued “interpersonal and communication” skills in addition to ‘strategic thinking” and “project management” know-how. The survey, which was conducted in 2007, found that 73% of respondents said they planned to upgrade their business skills within two years, with the majority studying for project management skills. 2. Programming Languages (C, C++, C#) Forget about programming jobs being outsourced, experts with C, C++ and C# skills “have emerged as a highly desired skill set, being cited as ‘in demand’ just as often as Business Intelligence and Enterprise Solutions skills,” according to the Veritude 2009 IT Outlook Report. Demand for soft...
Posts
Boder Gateway Protocol Message Type: Four different message types are used in BGP-4: • Open messages—Used to establish connections with peers. • Keepalives—Sent periodically between peers to maintain connections and verify paths held by the router sending the keepalive. These packets are sent unreliably. If the periodic timer is set to a value of 0, this equates to infinity, and no keepalives are sent. • Update messages—Contain paths to destination networks and the path attributes. Routes that are no longer available or withdrawn routes are included in updates. There is one path per update, requiring many updates for many paths. The information contained in the update includes the path attributes such as origin, Autonomous System path, neighbor, and inter-Autonomous System metric. • Notification—Used to inform the receiving router of errors.
Network Tools Traceroute : Traceroute transmits packets with small TTL values. Recall that the TTL (Time To Live) is an IP header field that is designed to prevent packets from running in loops. Every router that handles a packet subtracts one from the packet's TTL. If the TTL reaches zero, the packet has expired and is discarded. Traceroute depends on the common router practice of sending an ICMP Time Exceeded message, back to the sender when this occurs. By using small TTL values which quickly expire, traceroute causes routers along a packet's normal delivery path to generate these ICMP messages which identify the router. A TTL value of one should produce a message from the first router; a TTL value of two generates a message from the second; etc. In a typical traceroute session, a group of packets with TTL=1 are sent. A single router should respond, using the IP address of the interface it transmits the ICMP Timeout messages on, which should be the same as the interface it ...
Fragmentation and Reassembly To make IPv4 more tolerant of different networks the concept of fragmentation was added so that, if necessary, a device could break up the data into smaller pieces. This is necessary when the maximum transmission unit (MTU) is smaller than the packet size. For example, the maximum size of an IP packet is 65,535 bytes while the typical MTU for Ethernet is 1,500 bytes. Since the IP header consumes 20 bytes (without options) of the 1,500 bytes, 1,480 bytes are left for IP data per Ethernet frame (this leads to an MTU for IP of 1,480 bytes). Therefore, a 65,535-byte data payload (including 20 bytes of header information) would require 45 packets (65535-20)/1480 = 44.27, rounded up to 45. Fragmentation When a device receives an IP packet it examines the destination address and determines the outgoing interface to use. This interface has an associated MTU that dictates the maximum data size for its payload. If the MTU is smaller than the data size then the device...
IP Packet The Internet Protocol (IP) is a protocol used for communicating data across a packet-switched internetwork using the Internet Protocol Suite (TCP/IP). A packet is the unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network. Packet Structure : An IP packet consists of a header section and a data section. Header Section : The header consists of 13 fields, of which only 12 are required. The 13th field is optional . Version : The first header field in an IP packet is the four-bit version field. For IPv4, this has a value of 4 (hence the name IPv4). Header Length (HL) : The second field (4 bits) is the Internet Header Length (IHL) telling the number of 32-bit words in the header. Since an IPv4 header may contain a variable number of options, this field specifies the size of the header . The minimum value for this field is 5 which is a length of 5×32 = 160 bits. Being a 4-bit value, the maximum length is 15 words or 480 b...
ITIL : Information Technology Infrastructure Library Information Technology Infrastructure Library (ITIL) has been around for 20 year. ITIL is becoming the next big thing in Information Technology. It is the new industry buzz-word, the new certification, the new conference, and the new idea that the IT world feels it needs. Where did ITIL come from? ITIL started in the late 1980s when the British Central Computer and Telecommunication Agency (CCTA), now called the Office of Government Commerce (OGC), made a decision that there should be a better way for Information Technology to function. The CCTA commissioned a study group to develop a new approach to managing Information Technology. From this group came Version 1 of ITIL, which was called GITIM, Government Information Technology Infrastructure Management. Version 1 of ITIL was a great deal different from the present-day version. Part of this difference is due to the gradual maturing of ITIL and changes in the Information Technology ...
Multicast : Why Use it
When multiple receivers are required to get the same data at approximately the same time, multicast is a more efficient way of delivering data than unicast. A unicast packet has a single source IP address and a single destination IP address. A multicast packet has a single source IP, but it has a multicast destination IP address that will be delivered to a group of receivers. Click here to View the advantages of multicast over unicast delivery.