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My CCNA / HND Computer networking blog

Discussion in 'General Cisco Certifications' started by datarunner, Nov 13, 2007.

  1. datarunner

    datarunner Byte Poster

    hi all

    im a 2nd year computer networking student (CCNA / HND) and i would like to start my own blog discussing the things we were taught that day. at the moment we are studying routing and switching using physical equipment and router sim. Would this be possible in this thread (or at all)? i will update daily and all comments / help would be very welcome. regards.
    Certifications: A+, N+, MCP 210, 270, HNC Networking
  2. zimbo
    Honorary Member

    zimbo Petabyte Poster

    i would be keen since im a 2nd year in a B.Sc Comp networks major... althought our program doesnt include Cisco stuff i would be keen to learn from it...
    Certifications: B.Sc, MCDST & MCSA
    WIP: M.Sc - Computer Forensics
  3. datarunner

    datarunner Byte Poster

    OK i will summarise what we have been taught so for and post it tho it might be basic for some members. Any error corrections or further info is greatly appreciated especiallyfrom those who work with this stuff daily.

    Certifications: A+, N+, MCP 210, 270, HNC Networking
  4. datarunner

    datarunner Byte Poster

    Intro to routing protocols

    A router must have a routing table to route information.
    2 methods exist to create these tables - Static and Dynamic

    With static the network admin manually enters the routing table
    This is done via the command line interface and must be configured in both directions otherwise traffic will only be one way
    Used for backup communications or for specific connections / cost lowering

    With dynamic the routing protocol adjusts the routing table automatically for topology or traffic changes
    2 main types: IGP (Interior gateway protocol) and EGP (Extension gateway protocol)
    IGPs operate within an autonomous system (IGRP, RIP, EIGRP, OSPF)
    EGPs connect different autonomous systems (BGP)

    Routing Algorithms

    No matter which routing protocol you use an algorithm will be run to define the routes available. These algorithms can be grouped in to 3 distinct areas:

    Distance vector - Will determine the direction (vector) and distance (hops) RIP, IGRP
    Hybrid - Uses a combination of distance vector and link state EIGRP
    Link state - Uses shortest path OSPF
    Certifications: A+, N+, MCP 210, 270, HNC Networking
  5. Spice_Weasel

    Spice_Weasel Kilobyte Poster

    A useful introductory summary. One thing to watch out for - strictly speaking, eigrp is a distance vector protocol. Although it is often refered to as a hybrid protocol it is actually a distance vector protocol. This can lead to one of those times when there is a "test" answer and a "real world" answer - a test question may expect you to call eigrp a hybrid protocol, but at its heart it is a DV protocol, with some unique features. But on tests eigrp is generally considered a hybrid protocol.

    Certifications: CCNA, CCNP, CCIP, JNCIA-ER, JNCIS-ER,MCP
  6. Kraven

    Kraven Kilobyte Poster

    Yeah I'd definitely like to see what you learn as I am thinking about doing the CCNA after the MCSA.

    Certifications: Network+, MCSA, 70-680
    WIP: A+, 70-685
  7. datarunner

    datarunner Byte Poster

    thanks for the encouragement guys. I will add some more stuff l8r
    Certifications: A+, N+, MCP 210, 270, HNC Networking
  8. datarunner

    datarunner Byte Poster

    RIP Versions

    RIP (Routing information protocol) comes in 2 flavours

    RIP version 1 only supports classful IP addresses / subnet masks (wont route / recoqnise subnetted networks)
    RIP version 2 can support classless (subnetted networks, CIDR, VLSM etc)

    Routers set up with RIP will send RIP info at regular intervals and during these intervals will tell neighbouring routers about networks they have attached to themselves. Also any newly found networks will be advertised but the routers will alter the hop count metric to reflect how far away these networks actually are

    Amazing things routers.
    Certifications: A+, N+, MCP 210, 270, HNC Networking
  9. datarunner

    datarunner Byte Poster


    OK as we have an assessment on routers next week i thought id include some of the stuff we will be tested on. The info will be based around CISCOs 1841 / 2600 routers, IOS 12.4 and some basic router commands

    So what is a router?

    A network device that forwards data from network to network, ie from a LAN to another LAN, or LAN to WAN etc. As routers work at layer 3 of the OSI model they forward data based on the logical (IP) address and because they function at layer 3 they can connect different types of networks ie FDDI to ethernet.

    Router Components

    Routers are similar to PCs in that they have:

    • Processor
    • System bus
    • Interfaces
    • Memory

    The main componenents of a router are:

    RAM - stores the routing tables, loses its contents when powered down
    NVRAM - holds the config file and is not lost when powered down
    ROM - holds the bootstrap that loads the basic OS and performs POST. OS upgrades

    Connecting To A Router

    Alot of routers come with a GUI controlled via a web interface however most if it not all CISCO routers run an OS with a command line interface. To connect to this interface we use a PC connected to the routers console port via console / roll over cable. We connect this cable to a COM / SERIAL port on the back of the PC using a DB-9 connector.

    Once we have done this we run a windows utility called hyperterminal and set it up with the following settings:

    Choose COM port 1 or 2
    Set the baud to 9600
    Set the parity bit to 0
    Set the data bits to 8 (default)
    Set the stop bits to 1 (default)
    Set the flow control to None

    We are now able to connect to the router and use its OS. We start this by pressing enter.

    Router Modes

    Once the router has booted up we are prompted to press enter. Here we are presented with a > prompt. This is admin or user exec mode. Information can only be viewed here.

    To get from admin / user exec mode we type en. This takes us to privileged mode and is represented with a # prompt.

    To get to global exec mode we type conf t and this is represented with router(config)#

    To switch between admin / user exec modes we type enable or disable
    To switch between other modes we type exit or CTRL Z to return to admin / user exec mode

    Passwords can be set between modes
    Certifications: A+, N+, MCP 210, 270, HNC Networking
  10. Delgee

    Delgee Bit Poster

    Usually hyperterminal is mentioned because it comes with windows. But there are many other softwares dedicated for configuring routers, switches etc... A very good example is SecureCRT application.
    Also the baud rate doesn't really have to be 9600. Yes almost all equipments support this rate but many equipments can also support higher rates 115200 etc...
    I think the most important thing routers do is route the traffic, find the best path and do the best effort-delivery.
    Good luck and will comment on your posts in future. Keep up the work :D
    Certifications: CCNA
    WIP: CCNA Voice

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