Network and Security

Wide Area Networks Wide Area Networks can be seen as connection pipes that interconnect Local Area Networks. Usually WANs in contrast to LANs are not owned by the public; they are owned by service providers and their functionality-infrastructure is leased in order for LANs to be able to extend their expandability and make use of distant-remote services. A number of different WAN connection types exist today. Choosing the right WAN connection type is up to you, but the information in this article will make your decision process much easier. WAN Connection Types Leased Line: This is considered to be a dedicated point-to-point connection type where a permanent communication path exists between a Customer Premise Equipment (CPE) on one site and a CPE at the remote site communicating through a Data Communicating Equipment (DCE) within the providers’ site. Synchronous serial lines are used for this connection and the most frequent protocols observed in these lines are HD

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,

The "heart" of the Internet as we know it today is the Internet Protocol (IP) which is responsible for routing data to the appropriate destination. It belongs to the group of routed protocols like IPX (Internetwork Packet Exchange), but unlike other routed protocols, the IP was designed to serve the Internet and its internetworks. In addition to IP, the Internet has various control protocols operating at the network layer (layer three of the OSI model), including: ICMP: Internet Control Message Protocol ARP: Address Resolution Protocol RARP: Reverse Address Resolution Protocol BOOTP: Bootstrap Protocol DHCP: Dynamic Host Configuration Protocol So let’s take a look at these protocols in more detail! ICMP: Internet Control Message Protocol ICMP protocol was designed with the unreliable characteristics of the IP protocol in mind. Due to the unreliability and the connectionless behavior of IP there was no way of informing the originator