Network and Security

Benefits of VLSM VLSM provides the ability to subnet an already subnetted network address. The benefits that arise from this behavior include: Efficient use of IP addresses: IP addresses are allocated according to the host space requirement of each subnet. IP addresses are not wasted; for example, a Class C network of 192.168.10.0 and a mask of 255.255.255.224 (/27) allows you to have eight subnets, each with 32 IP addresses (30 of which could be assigned to devices). What if we had a few WAN links in our network (WAN links need only one IP address on each side, hence a total of two IP addresses per WAN link are needed). Without VLSM that would be impossible. With VLSM we can subnet one of the subnets, 192.168.10.32, into smaller subnets with a mask of 255.255.255.252 (/30). This way we end up with eight subnets with only two available hosts each that we could use on the WAN links. The /30 subnets created are: 192.168.10.32/30, 192.168.10.36/30, 192.168.10.40/30,

Let’s start with simple explanation of the new format. As you may know, the new-generation-IP talk started in the early 1990s when we were slowly running out of IP addresses. We had quite a few proposals for the new address format but in 1995 IPv6 was selected and the RFCs were officially entered into the RFC repository. IPv6 was created based off of IPv4 with some of the useful IPv4 features carried over to IPv6. There were many changes to the new IP format, however, and I will list some of them here below. Expanded Addressing Capabilities : IPv6 address size increased from 32 bits to 128 bits. Because of the increased size the new address will support a higher number of nodes, more levels of addressing hierarchy, and a much simpler autoconfiguration of addresses for remote users. A new address type was created, called anycast . Header Format Simplification : To simplify the entire IP format, some of the IPv4 header fields were dropped or made optional in IPv6. Fl

The Transmission Control Protocol/Internet Protocol (TCP/IP) suite was created by the U.S. Department of Defense (DoD) to ensure that communications could survive any conditions and that data integrity wouldn’t be compromised under malicious attacks. The Open Systems Interconnection Basic Reference Model (OSI Model) is an abstract description for network protocol design, developed as an effort to standardize networking. In this article, I will present the differences between the DoD and the OSI models and then provide details about the DoD’s version of TCP/IP. I will also describe the protocols used at the various layers of the DoD model and provide you with the details of TCP and UDP protocols. Throughout this article you will find useful information concerning the protocol suite of the century: TCP/IP. So if you’re preparing for your CCENT or CCNA exams, or if you’re just interested in networking, this is one article you don’t want to miss! Fasten your s