TCP/IP Tutorial: Dynamic vs. Static IP Addressing
Part 1 | Part 2
In our continuing protocol tutorial series, we now turn our focus from SNMP to a broader yet critical element of network management - IP addressing. Proper IP addressing is essential for establishing communication between any two network elements. The fundamental rule is simple: every network element must have a unique IP address. IP addresses can be assigned dynamically - on an as needed basis, or statically - usually on a permanent basis.
Static assignment of IP addresses is typically used to eliminate the network traffic associated with DHCP/DNS and to lock an element in the address space to provide a consistent IP target.
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Dynamic assignment of IP address is implemented using a protocol called, logically enough, the Dynamic Host Configuration Protocol (DHCP). When DHCP is active, it typically works in conjunction with a Domain Name System (DNS) to allow users to find an element's address. Surfing the World Wide Web makes extensive use of these two protocols. When you dialup to your Internet service provider (ISP), DHCP is used to assign an IP address to your connection. When you enter a WWW address in your browser address bar or select a human-readable link on a web page, a DNS is used to turn your URL request into an IP address for transmission. These services can also be used in a directly connected network and in either case are typically administered by the information services (IS) department.
Static assignment of IP addresses is typically used to eliminate the network traffic associated with DHCP/DNS and to lock an element in the address space to provide a consistent IP target. Telemetry monitoring masters can then be told precisely where the element is located by entering the unambiguous IP address. Though not usually discernable over a dialup connection, you can observe this effect by replacing a typical WWW reference with its direct IP address. For example, enter "209.240.134.104" in your browser address bar and, with no DNS overhead, you will reach the same web page you would reach by entering "www.dpstele.com."
In our next article, we will look into the specifics of static IP address assignment. Though the assignment is ordinarily done by the same IS department that administers the DHCP/DNS system, understanding the mechanism is often invaluable in the installation, turn-up and support of alarm masters and telemetry remotes in an IP network.
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| Dynamic vs. Static IP Addressing |
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