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Client/Server Versus Peer Networks

LAN 101: Networking Basics
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Although every device on a LAN is connected to every other device, they do not necessarily communicate with each other. There are two basic types of LANs, based on the communication patterns between the machines: client/server networks and peer-to-peer networks.

Client/Server Networks

On a client/server network, every computer has a distinct role: that of either a client or a server. A server is designed to share its resources among the client computers on the network. Typically, servers are located in secured areas, such as locked closets or data centers (server rooms), because they hold an organization’s most valuable data and do not have to be accessed by operators on a continuous basis. The rest of the computers on the network function as clients (see image below).

The components of a client/server LAN.The components of a client/server LAN.

A dedicated server computer often has faster processors, more memory, and more storage space than a client because it might have to service dozens or even hundreds of users at the same time. High-performance servers typically use from two to eight processors (and that’s not counting multi-core CPUs), have many gigabytes of memory installed, and have one or more server-optimized network interface cards (NICs), RAID (Redundant Array of Independent Drives) storage consisting of multiple drives, and redundant power supplies. Servers often run a special network OS—such as Windows Server, Linux, or UNIX—that is designed solely to facilitate the sharing of its resources. These resources can reside on a single server or on a group of servers. When more than one server is used, each server can “specialize” in a particular task (file server, print server, fax server, email server, and so on) or provide redundancy (duplicate servers) in case of server failure. For demanding computing tasks, several servers can act as a single unit through the use of parallel processing.

A client computer typically communicates only with servers, not with other clients. A client system is a standard PC that is running an OS such as Windows. Current OSes contain client software that enables the client computers to access the resources that servers share. Older OSes, such as Windows 3.x and DOS, required add-on network client software to join a network.

Peer-to-Peer Networks

By contrast, on a peer-to-peer network, every computer is equal and can communicate with any other computer on the network to which it has been granted access rights. Essentially, every computer on a peer-to-peer network can function as both a server and a client; any computer on a peer-to-peer network is considered a server if it shares a printer, a folder, a drive, or some other resource with the rest of the network. This is why you might hear about client and server activities, even when the discussion is about a peer-to-peer network.

Peer-to-peer networks can be as small as two computers or as large as hundreds of systems and devices. Although there is no theoretical limit to the size of a peer-to-peer network, performance, security, and access become a major headache on peer-based networks as the number of computers increases. In addition, Microsoft imposes a limit of only 5, 10 or 20 concurrent client connections to computers running Windows. This means that a maximum of 20 (or fewer) systems will be able to concurrently access shared files or printers on a given system. This limit is expressed as the “Maximum Logged On Users” and can be seen by issuing the NET CONFIG SERVER command at a command prompt. This limit is normally unchangeable and is fixed in the specific version and edition of Windows as follows:

  • 5 users: Windows XP Home, Vista Starter/Home Basic
  • 10 users: Windows NT, 2000, XP Professional, Vista Home Premium/Business/Enterprise/Ultimate
  • 20 users: Windows 7 (all editions)

When more than the allowed limit of users or systems try to connect, the connection is denied and the client sees one of the following error messages:

Operating system error 71. No more connections can be made to this remote computer at this time because there are already as many connections as the computer can accept.

System error 71 has occurred. This remote computer has reached its connection limit, you cannot connect at this time.

Even though it is called a “Server” OS, Windows Home Server also has the same 10-connection limit as the non-Home client Windows versions of XP and Vista. If you need a server that can handle more than 10 or 20 clients, I recommend using a Linux-based server OS (such as Ubuntu Server) or one of the professional Windows server products (such as Windows 2000 Server, Server 2003, Server 2008, Essential Business Server, or Small Business Server). Peer-to-peer networks are more common in small offices or within a single department of a larger organization. The advantage of a peer-to-peer network is that you don’t have to dedicate a computer to function as a file server. Instead, every computer can share its resources with any other. The potential disadvantages to a peer-to-peer network are that typically less security and less control exist because users normally administer their own systems, whereas client/server networks have the advantage of centralized administration.

Note that the actual networking hardware (interface cards, cables, and so on) is the same in client/server versus peer-to-peer networks, it is only the logical organization, management and control of the network that varies.

Comparing Client/Server and Peer-to-Peer Networks

Client/server LANs offer enhanced security for shared resources, greater performance, increased backup efficiency for network-based data, and the potential for the use of redundant power supplies and RAID drive arrays. Client/server LANs also are more expensive to purchase and maintain. The following table compares client/server and peer-to-peer server networking.

Comparing Client/Server and Peer-to-Peer Networking
Item
Client/Server
Peer-to-Peer
Access controlVia user/group lists of permissions Via user/group lists of permissions to only the resources granted, and different users can be given different levels of access.Resources are managed by each system with shared resources. Depending on the OS, resources may becontrolled by separate passwords for each shared resource or by a user list stored on each system with shared resources. Some OSs do not use passwords or user/group lists, thus enabling access to shared resources for anyone accessing the network.
Security
High; access is controlled by user or by group identity.
Varies; if password protection is employed, anyone who knows the password can access a shared resource. If no passwords are used, anyone who can access the workgroup can access shared resources. However, if user/group names are used,security is comparable to a client/server network.
Performance
High; the server is dedicated and doesn’t handle other tasks.Low; servers often act as workstations.
Hardware Cost
High; specialized high-performance server hardware with redundancy features.Low; any workstation can become a server by sharing resources.
Software Cost
Higher; license fees per user are part of the cost of the server OS.Lower; client software is included with OS.
Backup
Centralized on the server; managed by network administrator. Backup by device and media only required at server.Decentralized; managed by users. Backup devices and media are required at each workstation.
Redundancy
Yes; duplicate power supplies, hot-swappable drive arrays, and even redundant servers are common; network OS normally is capable of using redundant devices automatically.No true redundancy among peer “servers” or clients; failures require manual intervention to correct, with a high possibility of data loss.
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  • 9 Hide
    iam2thecrowe , September 15, 2011 6:25 AM
    I know a lot of so called "I.T." companies that could learn a thing or two, like how to plug a cable in and how to diagnose a fualty cable/patch point, instead of calling the printer guy out to troubleshoot their network problems for them. IT guys are so lazy sometimes.
  • -5 Hide
    LORD_ORION , September 15, 2011 2:03 PM
    OK seriously, you cannot even do a book prize internationally?

    Lame.

    You suck etc...
  • 0 Hide
    nevertell , September 15, 2011 2:15 PM
    A true fileserver is running linux :>
  • 6 Hide
    Pyree , September 15, 2011 3:23 PM
    I think this should become a sticky on the network forum.
  • 0 Hide
    amk-aka-Phantom , September 15, 2011 3:59 PM
    Nice article. Bookmarked for future reference... some of my friends could use these basics and the article is well-written and simple to understand :) 
  • 8 Hide
    cangelini , September 15, 2011 4:34 PM
    LORD_ORIONOK seriously, you cannot even do a book prize internationally?Lame.You suck etc...


    Nope, we can't unfortunately. The same tax laws and rules that apply to $100 motherboards and $1000 CPUs also apply to $60 books.

    A letter to your congressman about our ridiculous tax laws would be more productive ;) 
  • 1 Hide
    amk-aka-Phantom , September 15, 2011 4:51 PM
    Quote:
    Nope, we can't unfortunately. The same tax laws and rules that apply to $100 motherboards and $1000 CPUs also apply to $60 books.

    A letter to your congressman about our ridiculous tax laws would be more productive ;) 


    Lol, I accept that explanation readily, as much as I hate all these kick-ass US-only draws. Taxes are a party crasher...
  • 1 Hide
    jryan388 , September 15, 2011 9:15 PM
    I was under the impression that cat6 cable was required for gigabit ethernet...
  • 0 Hide
    Proximon , September 15, 2011 9:59 PM
    It really is an impressively clear and complete book. It's quite a skill to cover topics like this in a way that doesn't require too much background knowledge first.
  • 0 Hide
    soccerdocks , September 16, 2011 12:33 AM
    jryan388I was under the impression that cat6 cable was required for gigabit ethernet...


    I was too. But it sounds like as long as your CAT5e cable is short enough it will work. Although probably not optimally.
  • 2 Hide
    michaelahess , September 16, 2011 2:17 AM
    Cat5e is fine for gigabit. I've had runs over 300ft work fine at 1Gb speeds.

    I didn't read very carefully but I didn't see anything in the wifi section about true transmission speeds. 54g will only net you 18-24Mb at the best, consistently. Fastest I've gotten outa any N gear is just shy of 250Mb/sec. And that was with high end Cisco gear at very short distance. Wireless is just too fickle for real high bandwidth stuff.

    I've been in the network provider (ISP) field for over 15 years. Anyone has any questions, just ask me. ;)  Ok don't really, I don't have the time!
  • 0 Hide
    Onus , September 16, 2011 4:43 PM
    ARCNet, Token Ring...that brings back a lot of memories. Then there was Corvus' Omninet...
  • 0 Hide
    chickenhoagie , September 18, 2011 9:14 PM
    guess my cisco class taught me a lot in highschool. still learned a few pointers in this article though
  • 0 Hide
    sysa , September 21, 2011 1:31 PM
    I did a little checking and found out that the 6200 series processors are Interlagos.
  • 1 Hide
    zodiacfml , September 22, 2011 3:06 AM
    wow, didn't know our ordinary ethernet only need two pairs of wires.
    i wonder why it had those extra pairs before gigabit ethernet.
  • 1 Hide
    thegame8019 , September 22, 2011 7:26 PM
    I am currently enrolled in Cisco's academy and this article has made a few things a little more clear to me.
  • 0 Hide
    PhoneyVirus , September 23, 2011 7:59 PM
    I have this book 10 feet from me but I'm not aloud with it until Christmas because the girlfriend would kill me, the only way I could look at it is I would have to where a pair of rubber gloves so there wouldn't be any finger prints on the hard cover and not to break the book in so I'll wait until Christmas and it can't come fast enough.

    Also amk-aka-phantom this book should be on your book shelf and NOT Bookmarked in the browser, Read this book remember all you can build your self a system, Read Microsoft Windows Inside Out, Remember your Keyboard Short Cuts aka Run Commands, Conquer the Command prompt, program simple VBScripts, Batch files and you will have no problem running a little PC Repair shop.

    PhoneyVirus
  • 0 Hide
    amk-aka-Phantom , September 23, 2011 8:25 PM
    Quote:
    Also amk-aka-phantom this book should be on your book shelf and NOT Bookmarked in the browser, Read this book remember all you can build your self a system, Read Microsoft Windows Inside Out, Remember your Keyboard Short Cuts aka Run Commands, Conquer the Command prompt, program simple VBScripts, Batch files and you will have no problem running a little PC Repair shop.


    Umm... thank you, but I know enough about PCs and networking without any books.