router contains a built-in switch versus router without a built-in switch

Discussion in 'Windows Networking' started by jrefactors, Sep 15, 2005.

  1. jrefactors

    Travis Guest

    It is called Network Address Translation.
     
    Travis, Sep 18, 2005
    #21
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  2. I think you will find that the truth is far far worse than you could
    ever imagine.

    'home routers' are - i've been told - are not routers. They are NAT
    devices. They contain a switch. And a firewall. And a modem.


    Regarding 'routers' without a built in switch . May be a real router.
    Or it may be a simple thing.
    Often so-called DSL Modems like ones made by DLink or Linksys, are
    actually 'home routers' with only 1 port. NAT devices without a
    switch. so if you want to connect many computers, then attach your own
    switch.

    Professional proper routers (like Cisco) have many ports, each is a
    router interface, each with its own IP. Each is for a connected
    network.
    No switch.

    a NAT Device receiving an incoming packet, does not 'route it', it does
    not decide what network to sends the packet to. Only your network is
    attached. It just allows it or rejects it. And depending on how it is
    configured, sends the packet to whatever computer is attached. Go to
    www.whatismyip.com and i you're behind a NAT device, you get the IP
    Address of your NAT device. People send packets not to you, but to
    your NAT device. Your NAT device does port forwarding to choose which
    of your comp on your network to send it to. This is not routing at
    all. Routing is about deciding which network to (not which comp and not
    just on 1 network) send it to, using routing tables, and the Sending
    computer will include the Dest IP of teh network to send to. With NAT,
    the sending computer only specifies the NAT device. So the NAT device
    is choosing which comp to send it to. With a *Router*, (not a 'home
    router'). Packets are not addressed to the Router, they are addressed
    to the comp. The Router doesn't choose which local comp to send it to,
    it looks at the IP, sees it doesn't have to route it anywhere, since it
    is on a directly connected network, and it sends it to the right
    computer.


    I am a newbie, and will be using real routers this year! But I read
    about them. I am just interested in computers and connecting them
    together. So, frmo a techie perspective, a real router is more fun.
    likely), then a NAT device ('home router') is fine.

    Linksys make good 'home routers'(NAT Devices), get one with a built in
    switch. And a hole for a telephone cable - meaning it has a built in
    modem. 4 port switch, So you can attach - say - 4 computers. If you
    want more you can connect another switch to a port anyway.
     
    jameshanley39, Sep 18, 2005
    #22
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  3. jrefactors

    Leythos Guest

    They do not contain a Firewalll.

    They do not contain a MODEM.

    They do contain a Switch.

    They do contain a NAT routing function and also do RIP1 and RIP2, which
    makes them routers.
     
    Leythos, Sep 18, 2005
    #23
  4. 'home routers' are - i've been told - are not routers. They are NAT
    Home routers ARE routers.
    They route between the outside network (the network between the home router
    and the first router at your ISP) and the internal network (the
    non-world-visible home network you have).
    They can contain a firewall and indeed some do.
    They also implement Network Address Translation (or NAT) and Port Address
    Translation (or PAT aka port forwarding) and they contain a cable or DSL
    MODEM (whether it is techincally a MODEM, all the manufacturers call it a
    MODEM).
    They will also usually contain a DHCP server to assign IP addresses to all
    the machines on the internal network.

    For example in my case, we have a single IP address from the ISP.

    My PC has a private address (in the 192.168.1.x range).
    Other PCs in this house also have a 192.168.1.x address, as does the router
    itself.
    So, all the machines on the internal network including the router make up
    the 192.168.1.x class C private network.
    Then, there is another network with my home router on it plus the router at
    the ISP.
    The home router routes traffic between the 192.168.1.x network and the
    router-ISP network.
     
    Jonathan Wilson, Sep 18, 2005
    #24
  5. Oh and btw, I am currently studying Cisco CCNA network certification so I
    DO know what I am talking about :)
     
    Jonathan Wilson, Sep 18, 2005
    #25
  6. jrefactors

    Leythos Guest

    Except that certification and claiming to have some book learning
    doesn't mean anything to fanatics or people that hire IT types :)
     
    Leythos, Sep 18, 2005
    #26
  7. From: "Leythos" <>

    |
    | They do not contain a Firewalll.
    |
    | They do not contain a MODEM.
    |
    | They do contain a Switch.
    |
    | They do contain a NAT routing function and also do RIP1 and RIP2, which
    | makes them routers.
    |
    | --
    |
    |
    | remove 999 in order to email me

    Actually...

    The MAY contain any or all of these. It all depends on makes and models.
    For example the Estwll 327W is both a DSL modem in Bridge mode and a DSL Modem/Router when
    placed in Router mode.
     
    David H. Lipman, Sep 18, 2005
    #27
  8. David H. Lipman, Sep 18, 2005
    #28
  9. jrefactors

    CJT Guest

    Given your credentials, you must know that is sometimes, but not always
    true. Not all home routers contain what manufacturers call a modem;
    that is a separate function.

    Some also contain PPPoE or similar functionality.
     
    CJT, Sep 18, 2005
    #29
  10. Given your credentials, you must know that is sometimes, but not always
    I was unaware that routers exist that do not contain modems (actually, I
    probobly knew at one point and just forgot :)
     
    Jonathan Wilson, Sep 18, 2005
    #30
  11. | I was unaware that routers exist that do not contain modems (actually, I
    | probobly knew at one point and just forgot :)

    Joint modem+Router devices are relatively new. When SOHO Routers first hit the market,
    there weren't any joint versions. They were all Routers only or modem only.
     
    David H. Lipman, Sep 18, 2005
    #31
  12. jrefactors

    Leythos Guest

    That would make it more than a NAT Router then :)
     
    Leythos, Sep 18, 2005
    #32
  13. |
    | That would make it more than a NAT Router then :)
    |
    | --
    |
    |
    | remove 999 in order to email me

    Well Westell is known for making DSL modems. The product lines are morphing and
    assimilating.

    It is the Borgs ! ;-)
     
    David H. Lipman, Sep 18, 2005
    #33
  14. jrefactors

    Leythos Guest

    Yea, that type of crap really irritates me - I'm the type that purchases
    a stand-alone access-point, not a wireless router, so that I can change
    things as needed without impacting everything else.

    I would hate to find that my Modem had an exploit that filters through
    the NAT firmware, that would have been blocked if I had installed a
    stand-alone NAT router.
     
    Leythos, Sep 18, 2005
    #34
  15. From: "Leythos" <>


    |
    | Yea, that type of crap really irritates me - I'm the type that purchases
    | a stand-alone access-point, not a wireless router, so that I can change
    | things as needed without impacting everything else.
    |
    | I would hate to find that my Modem had an exploit that filters through
    | the NAT firmware, that would have been blocked if I had installed a
    | stand-alone NAT router.
    |
    | --
    |
    |
    | remove 999 in order to email me

    I agree. Greater versitility and no single point of failure.

    I wonder -- If a modem can be put in either a Bridge mode or a Router mode, are they then
    BRouters ?
     
    David H. Lipman, Sep 19, 2005
    #35
  16. jrefactors

    CJT Guest

    No single point of failure? How so?
     
    CJT, Sep 19, 2005
    #36
  17. | No single point of failure? How so?
    |

    If the Router+modem goes both are dead. If you separate products and the Router dies, you
    can still connect at least one PC to the modem.
     
    David H. Lipman, Sep 19, 2005
    #37
  18. jrefactors

    CJT Guest

    So then the modem is a single point of failure.
     
    CJT, Sep 19, 2005
    #38
  19. From: "CJT" <>


    | So then the modem is a single point of failure.
    |
    | --
    | The e-mail address in our reply-to line is reversed in an attempt to
    | minimize spam. Our true address is of the form .

    Well there is always a weak link in any chain. It is admittedly a weak argument but the
    versatility argument isn't.

    My father has a Westell 2200 ADSL modem+Router but it is in Bridge Mode and he's using a
    Linksys BEFSR41 v3 Router.

    I have a White Westell (modem only and have had it for over 5.5 years w/o any failures) and
    use a Linksys BEFSR81 v1 Router.
     
    David H. Lipman, Sep 19, 2005
    #39
  20. The NAT device/home router, would still have an IP address, so it
    wouldn't be a switch.

    The home router would still respond to an ARP request - for its MAC
    address, given its IP address. A switch would not do that.



    agreed. interesting concept. But as soon as you send a frame to the
    switch, and the MAC address is the MAC address of the router, rather
    than the MAC address of another computer on the LAN, then the frame
    will be pased by the switch to the home router, and the home router
    will do whatever a home router does. If the IP address is private then
    i don't know what the home router does. And if the IP address is not
    private then the frame is sent out , to the ISP's router.

    So, it is not just a switch. Frames can be addressed to the home
    router, the home router has an IP, the home router makes some kind of
    home router decisions on the IP. You can get past the switch.

    I have heard that cisco make some kind of manageable layer 3 switch,
    like a switch that uses IP addresses, but I doubt home routers are
    anything like these!
     
    jameshanley39, Sep 19, 2005
    #40
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