Explaining IP Network Connections by Phil Hippensteel - AvNetwork.com

Explaining IP Network Connections by Phil Hippensteel

Author:
Publish date:

Dear Professor Phil,
What happens when a device connects to an IP network?
Simon, West Chester, PA



Simon, you’ve asked a question about something that all of initiate on our computers every day but rarely contemplate exactly what it requires. As soon as there is a physical connection to a network switch, your network card negotiates a speed with the switch. When that succeeds, a link light usually appears on the side of the physical connector where you plug in your cable.

Your pc must know several critical values to function with other network devices. These ordinarily include an IP address, subnet mask, local router, and DNS (domain name services) server. If the device associates automatically with a server, such as entering a Windows domain or connecting to a VoIP call server, it may also need the servers’ IP addresses.

The address, mask, router, and DNS server can be configured in a Windows screen. Or, on that screen you can tell your software to obtain the values automatically by using DHCP (dynamic host configuration protocol). If you choose automatically, your software will broadcast a request and a server will supply the values that your software requires.

When the first network request is ready to be sent, for example to google.com, the following sequence occurs:

1) Your browser knows the name google.com but not the corresponding address. So, it creates a DNS query to be sent to the DNS server. If the server is on the local network, your software sends an ARP (address resolution protocol) broadcast asking for the DNS server’s hardware address.

2) The DNS server responds with its hardware address and the request can be forwarded to the server. Your pc software places the hardware address in a cache (memory buffer) for use with future requests.

3) The request to connect to google. com can be created and sent. However, if your software doesn’t have the router’s address, it may then need to send an ARP broadcast to get it.

Phil Hippensteel is a professor of Information Systems at Penn State Harrisburg. If you have a question for Professor Phil, email it to AVTintern@nbmedia.com.

Related

Explaining the IP Subnet Mask by Phil Hippensteel

Dear Professor Phil: What is the purpose of the IP subnet mask and how does it work? Scott, Charlotte, NC Hello Scott. The answer to this question has two parts.  The first involves the interpretation of the IP address.  IP addresses are 32 bits (four bytes) long. Devices interpret the address as two parts:

Understanding IPTV by Phil Hippensteel

Dear Professor Phil There is something that confuses me.  I know that changing channels in an IP video network takes longer because of a fact related to IP addressing, but I not sure of the details.  Also, why do these changes happen quickly in some cases but much more slowly in other cases? Kevin, Houston, TX  

Digital Video and IP Video are Not the Same by Phil Hippensteel

Dear Professor Phil, I continually hear people talking about digital video and IP video as if they are the identical.  Are they the same? Sam,  Hershey, PA Sam, They are not, but they are closely related terms. Consequently, you are correct that many people who are very familiar with analog video seem to confuse

Will the Change from IP v4 to IP v6 Impact AV Pros? by Phil Hippensteel

Dear Professor Phil, I’ve heard a lot about the change from IP version four to IP version six.  Is it really a big deal to AV professionals? Ben, Atlanta, GA Yes, it is a really big deal. Many people think that the significant issue is the change in the size of the IP address. It’s changing from four bytes to six

What causes “tiling” in video? by Phil Hippensteel

Dear Professor Phil: What causes “tiling” in video, particularly when watching HDTV? Jose, Tampa, Fl Hello Jose, To understand what causes tiling, we must first understand certain aspects of MPEG compression. This is the compression method used by nearly all modern video systems. The camera typically records 30

Why Are Some Codecs Implemented in Software? by Phil Hippensteel

Dear Professor Phil: I understand that some video codecs are hardware devices and some are implemented in software.  Should I care about the difference, and is there a trend relative to this difference? Lorie, Everett, WA Hello Lorie, You are correct that video and audio codecs are implemented in both hardwar

Dispatch from Interop 2012 by Phil Hippensteel

Las Vegas isn’t usually cloudy, but Interop 2012 — a show devoted to IT innovation — was full of cloud signs, cloud talk, and cloud-related give-aways. Large and small vendors praised the idea of data, telephony, and video in the cloud.  It seemed as if  every major vendor at the Las Vegas show was on the bandwagon. H