Networking Tips Tricks

Hybrid ARQ A Hybrid ARQ system consists of combination of error control mechanism namely Forward Error Correction and Automatic Repeat Request. The function of FEC is to reduce the frequency of retransmission by correcting error pattern which occur most frequently. This increases the system throughput. In case of less frequent error occurrences which can be detected but not corrected, the receiver requests for retransmission. This in turn increases the reliability. Thus a proper combination of FEC and ARQ provides higher reliability than an FEC system alone and higher throughput than the system with only ARQ as error control mechanism. Hybrid ARQ is an important dynamic tool for maintaining QoS in modern wireless systems. Hybrid ARQ involves an encoded forward link for error correction and detection and a feedback link for possible retransmission. At the transmitter, parity bits are added to the data block to detect and correct errors. In case the receiver is not able to correct these ...

In part one of this article series on DHCP we went over a lot of the theory on the protocol itself. Specifically what types of messages there are, how DHCP works, and why it is normally used. In this last part we will look at two DHCP packets that exemplify what DHCP is all about. If you missed part one of this article series please read Understanding the DHCP Protocol (Part 1) . DHCP and you Part II In part one of this article series on DHCP we have seen that this protocol is typically enabled on most networks. This greatly eases the workload of the network administrator as DHCP will provide clients with key configuration details. Details such as what its IP address will be, the subnet mask, and the DNS servers it should use. Rather important information if you want to be able to access the Internet. Furthermore, we covered some of the various DHCP message types that you could encounter on a network. Well in this part of the article series we will actually look at two of the more comm...

DHCP is a little thought of protocol by many everyday computer users. Little do they know, though, that it plays a key role in the setup of their computer and how it is able to communicate. We shall explore its features and functionality within the confines of this two part article series. f you would like to read the second part of this series please read Understanding the DHCP Protocol (Part 2) . DHCP and you For many of the normal computer users out there today very little attention is paid to exactly how their computer goes about its business. This does not only include how your computer builds packets to convey information, but also how it initially gets the required information to set itself up to communicate. To whit, information such as its IP address, the DNS servers it will use, the DNS servers to use, amongst other critical details that your computer needs for it to access the Internet. Well what exactly is DHCP or as it is commonly known as; Dynamic Host Configuration Proto...

How to install and configure DHCP Server in Windows Server 2008 to provide IP addressing and DNS server information to your end users. Introduction Dynamic Host Configuration Protocol (DHCP) is a core infrastructure service on any network that provides IP addressing and DNS server information to PC clients and any other device. DHCP is used so that you do not have to statically assign IP addresses to every device on your network and manage the issues that static IP addressing can create. More and more, DHCP is being expanded to fit into new network services like the Windows Health Service and Network Access Protection (NAP). However, before you can use it for more advanced services, you need to first install it and configure the basics. Let’s learn how to do that. Installing Windows Server 2008 DHCP Server Installing Windows Server 2008 DCHP Server is easy. DHCP Server is now a “role” of Windows Server 2008 – not a windows component as it was in the past.

One of the most basic processes on a network is that of assigning IP addresses to network clients. Although there are many different types of DHCP servers that can do the job, you can configure Windows Server 2003 to act as a DHCP server. In this article, I will show you how. Years ago, I used to be a network administrator for an organization that had some rather odd security policies in place. One of the existing policies when I got there was that all computers had to be assigned a static IP address. DHCP servers were forbidden for security reasons. The result was a maintenance nightmare. Obviously, some servers have a legitimate need for static IP addresses, but usually it is perfectly acceptable for workstations to use dynamic IP addresses. Generally speaking, using static IP addresses on workstations is only truly feasible on small networks. Unfortunately, the network that I spoke of a moment ago was anything but small. It had 25,000 workstations.

"Dynamic Host Configuration Protocol (DHCP) is an IP standard designed to reduce the complexity of administering IP address configurations." - Microsoft's definition. A DHCP server would be set up with the appropriate settings for a given network. Such settings would include a set of fundamental parameters such as the gateway, DNS, subnet masks, and a range of IP addresses. Using DHCP on a network means administrators don't need to configure these settings individually for each client on the network. The DHCP would automatically distribute them to the clients itself. The DHCP server assigns a client an IP address taken from a predefined scope for a given amount of time. If an IP address is required for longer than the lease has been set for, the client must request an extension before the lease expires. If the client has not requested an extension on the lease time, the IP address will be considered free and can be assigned to another client. If the user wishes t...

I have an Oracle database(Oracle 9.2.0.1.0) running on RedHat Linux 7.2. The server has 1GB ram. The service was running in Archivelog mode.Service is set to autostart. Recently I found on restarting the server the listener started by the service did not. I started the service using STARTUP MOUNT and using ALTER DATABASE I stopped the archivelogs. I have posted my next few commands, kindly help me.... SQL> startup mount ORACLE instance started. Total System Global Area  426316116 bytes Fixed Size                  450900 bytes Variable Size            268435456 bytes Database Buffers          157286400 bytes Redo Buffers                143360 bytes Database mounted. SQL> alter database open resetlogs; alter database open resetlogs *