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Modem > Switch > Wifi Router

Discussion in 'Networking & Security' started by mittos, Jul 9, 2014.

  1. remixedcat

    remixedcat

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    Well my router is a Meraki z1 and I got two Aruba RAP109 APs and a Meraki MR12 AP.

    All enterprise gear here.
     
  2. Pehla

    Pehla

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    i just wanted to read and learn some about networking...,but daaaaamn this is confusing!!!
    i actualy have issues with my home network..,its moslty all wireles..,i have 5ghz kit on the roof and its powerd over ethernet,now afther that (thing)
    i conected i switch then have it separated to 3 diferent parts of house...(think of it as 3 diferent apartmans)
    now on my end of the cable i have 150n wifi router...,and when i conect it with my laptop i only get around 2mb/s speed and if im conected directly on the roof kit i get full speed the i pay for (6mb/s)
    bad cables?? bad aragments of the switches ,routers??
     
  3. lilhasselhoffer

    lilhasselhoffer

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    So let's break this down into a very simple situation. Assuming you've got more than a basic knowledge of routing please ignore what I'm about to say.

    Every single device connected to the internet has a two part address. Part 1 is based on hardware, and is called a MAC. This address is hard coded into the hardware, and is functionally never going to change. Part 2 is the IP address. This sucker can change, based upon assignment by any device. It is the one that networking generally uses so that you know where to send data packets.

    For the purposes of networking, a MAC is fundamentally ignored. Your ISP might limit the modem to allowing information through only to a single MAC address, but that's generally not a problem in home networking.


    The IP address is the difficulty here. It's a string of four numbers, which range from 0 to 255 (000.000.000.000 to 255.255.255.255), and function as a dynamic identifier of who is to receive data packets. Using another analogy, this is very much like an address.

    So routers, modems, and switches (hubs have functionally died, with the exception of USB) all serve different purposes in our analogy. The modem is responsible for converting our incoming and outgoing data into useable formats. In the simplest terms, that cat5 wire has 8 conductors and the cable modem connects with a single conductor. In the address analogy the modem is a post office. They transfer data.

    The switch is like an idiot savant post master. Switches transfer data very quickly, but can't assign anything an address dynamically (managed switches avoid this, but we're talking a consumer level piece of hardware). If someone's address appears, they deliver it wherever they remember that address being. This works great, assuming that you've got a big pool of static addresses. Referring back to the address pool, that means we could have about 255^4= 4.29 billion dynamic addresses for every connected device. Looking back at this possibility, it's unrealistic given that we already have more than 6 billion people on the planet.

    A router is the post master general. They can assign a single address to a large block of people, subsequently creating an artificial division of addresses for a single physical one. In the networking world, this is getting a single IP address, and connecting a dozen devices to the internet via that one address. The problem here is that routing requires more computational power, and introduces delays into the system. While this has largely been addressed with faster routers, it is always a concern.


    So, why do the astute people in this thread say modem->router->switch is the proper connection methodology? It's simple. The switch can't create an artificial network address pool, so it won't work the other way around. hypothetically you could viably have both of the following connected to the same exact network without any problem sending packets:



    modem-183.183.183.001->router
    -192.168.0.2->PC
    -192.168.0.3->PC
    -192.168.0.4->Switch
    -192.168.0.5->PC
    -192.168.0.6->TV


    modem-183.183.183.002->router
    -192.168.0.2->PC
    -192.168.0.3->PC
    -192.168.0.4->PC
    -192.168.0.5->Switch
    -192.168.0.6->PC
    -192.168.0.7->TV
    -192.168.0.8->PC


    In contrast, the switch could only do the following:

    modem-183.183.183.001->Switch
    -183.183.183.001->PC
    -183.183.183.001->PC
    -183.183.183.001->router
    -192.168.0.2->PC
    -192.168.0.3->TV

    As multiple devices share the same IP pool, all devices see the same data. With multiple devices trying to complete handshakes and the like, only one device will actually work. Thus, no home network can function as modem->switch->router.





    Now addressing speed, there's a bundle of problems there. Most routers have some sort of built-in filtering and security features. Certain ports are automatically closed, etc.... The net result of this is lower speeds, but greater protection against intrusion. It isn't by any means real protection, but it does offer cursory protection from drive-by pinging of ports to determine security flaws. Other routers have built-in firewalls, that inspect packet activity to try and prevent certain actions. Again, speed is given up for security.

    Hooking a computer directly up to the modem will always produce the greatest speeds, but it is inherently riskier than hiding behind protection. You decide what protection is reasonable, and how much speed you really need.




    Edit:
    Changed formatting of IP addresses. Not sure how to show this best...
     
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  4. OneMoar

    OneMoar

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    modem first then router then switch the switch CAN NOT GO BEFORE the router because the router is what handles DHCP
    Unless your router is utter crap or has some silly QOS enabled by default there should be none to little impact on performance
     
  5. eidairaman1

    eidairaman1

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    A router is a switch.

    Ive seen homes where theres a modem then a switch then a wifi router. Especially homes with a network panel. Uverse IP tv over ethernet can use a switch to feed data to all tvs as long as you have 1 line going from the R.G. to the switch.
     
  6. OneMoar

    OneMoar

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    depends on if the switch is a DUMB or smart switch
     
  7. eidairaman1

    eidairaman1

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  8. remixedcat

    remixedcat

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    yeah but do you use VLANs???
     
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  9. Mussels

    Mussels Moderprator Staff Member

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    no. a router is a switch with DHCP and routing - aka port forwards, automated or manual.

    If you disable all those features, a router can be turned into a switch... but if you treat them as the same, you're gunna have a very screwed up network.
     
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  10. lilhasselhoffer

    lilhasselhoffer

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    Put simply, no.

    Even a managed switch will require some extra chutzpah to create its own home network. Most of the time what you are getting here is a modem with a built-in router. That router isn't a separate device, and thus people often confuse the lack of an extra box for a lack of the device itself.

    If you spend a moment on a site like newegg, you might be able to clear this up. There are actually routers with only two ethernet ports. In this way they take data in, split it off, then send it out. Most routers need to be more functional, so they generally have a switch built into them. This is why you can have a 5 port router, a two port router, or a 24 port router. The description has, over time, simply become a router. Years ago it was a router with a built-in ## port switch.


    On the higher end side, some managed switches will come with rudimentary DHCP features. These things don't generally hit consumer hands, because the cost is much higher than your standard 5 port unmanaged gigabit switch.




    Moving on to the assertion about communication wiring, that is in the right ballpark, but at the wrong address.

    The difference in wiring is immaterial. Cat5, Cat5e, and Cat6 wires all have four pairs of twisted wires. Base 100, or fast ethernet, doesn't actively use all four pairs. Base 1000, or gigabit ethernet, does actively use all four pairs. Cat5 wiring can take the data transmission of gigabit ethernet speeds, but as the wire length increases cross-talk makes the transmission less and less reliable. Likewise, Cat6 wire could transmit fast ethernet speeds without a problem.

    The big improvement with gigabit networking is auto-negotiation of communication. Anyone who has been around the block for a while will tell you at least once they were thwarted by a surprise cross-over cable requirement, or have someone sure their hardware was broken because they connected everything up and used one cross-over cable somewhere (instead of straight-throughs).
     
  11. remixedcat

    remixedcat

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    You will need a L3 managed switch if you wanna do QoS, client management, VLANs, etc...
     

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