what are the rules and step to take when installing router, hugs,swiches

Posted on 2005-04-27
Last Modified: 2013-11-29
hi guys is me again thank for you hel before to samccarthy for you help well now i have learn alot about computer  now  the only thing is that i don't undurstand how to setup switche , router  how long they have to be from each other what are the rules for doing that becuase  someone want me to help then to steup a network using windows 2003 server can anyone help me next week i'm going for my a+ exam
Question by:smurfdesign
    LVL 27

    Accepted Solution

    I've taken the A+ and setting up switches and routers isn't on it.  You have to understand the OSI model, and where switches (layer 2) and routers (layer 3) fit on the model, but that's about it.

    A basic switch learns for itself.  You plug it in, turn it on, and it begins analyzing layer 2 (MAC addresses) information which passes through.  If it gets a frame it notes the source address and it puts the source MAC in its table as coming on that port - call it port 1.  If its table doesn't have an entry for the destination, it will FLOOD that frame to ALL ports.  Then, when the destination gets it and replies, the reply comes in and it will note that MAC address came in on port 2.  Now, it has entries for two devices on ports 1 and 2.  When those devices want to communicate with each other, the switch will consult its table and know to switch the frame over to port 1 or 2 only, without sending it to all ports, or any other port.  

    Beyond that, it's all customization and depends on the capabilities and features of the switch.  For instance, if it's a managed switch, you can change port speed and duplex, create Virtual Local Area Networks (VLANS), put an IP address on the switch to be able to manage it remotely, manage Spanning Tree Algorithm (STP), etc.

    For routers - they examine and make decision on Layer 3 information - network addresses.  We'll just discuss IP routers since they are the most common.  Routers will have 2 or more attached networks on different interfaces.  The interfaces can be different types - for instance Plain Old Telephone System (POTS), Serial, Copper Ethernet, Fiber Ethernet, and lots of others.  A router will get a packet and examine the destination IP address and consult a table it has - called a routing table - to make a decision on how to route the packet.  If it sees a destination in its table, it will use it and send it out the appropriate interface.  If it does not see the destination in its routing table, then if it has a "default gateway" or a "gateway of last resort" it will use that to send the packet - these usually are in the "direction" of the Internet.  If it does not have a default gateway, and does not know the destination the packet will be deleted - or "dropped".  Depending on how the Router is configured, it may or may not report back to the sender that it doesn't know how to reach the destination using Internet Control Message Protocol (ICMP) with a "destination net unreachable" message.

    Routers can learn of routes by either being directly connected, explicitly told with "static routes", or learning of them from other routers with "routing protocols".  

    Note - a routing protocol is a way for routers to talk to each other.  A routed protocol, or routeable protocol,  is one which can be routed by a router.  Routing Information Protocol (RIP) is a routing protocol.  IP is a routed protocol.  Netbeui is NOT a routed protocol.

    This is about as deep as the A+ exam gets on networking - besides configuring NICs on a PC.
    LVL 3

    Expert Comment

    To address the second part (about distances):

    Cat5 or cat6 (10/100/1000) runs generally like to be less than 100 meters long.  They can be longer, but it starts to have difficulty induced by the laws of physics.  These distances are from repeater to repeater; loops around punchdown panels, punchdown crossconnects, etc., all count towards the 100m limit.  

    Fiber (100/1000) has different maxes based on the type of fiber (multimode/single-mode) and the type of fiber NIC you're using, anywhere from about 550 meters to 80 km.
    LVL 27

    Expert Comment

    For the purposes of taking a test - the distance for 10baseT, 100baseTX, and 1000baseT over copper is 100m.  Period.  There's some specs that say 90m of structured cabling (in walls, etc.) and 10m of patch cabling.

    Other types of Ethernet cabling which are obsolete could be 10base-2 (coaxial cable 185m), 10Base-5 (Coaxial cable 500m), etc.  Check out this chart:

    For the A+ test, you MIGHT need to know this stuff, but probably pretty limited.  You could get by with memorizing 10baseT, base2 and base5, base100, fiber - short and long range (SX and LX).

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