designing a network with 10 broadcast domains and 32 collision domains. pls help me.

creeptedcreepted Posts: 13Member ■□□□□□□□□□
in CCNA & CCENT
I have a homework which I need to design a topology in packet tracer with 10 broadcast domains and 32 collision domains and my network should have 5 routers 10 switches 2 servers and 16 workstations( pc printer etc,) I have trouble in how do I connect the routers and the switch because the switches. and also I have trouble counting broadcast domains. I am not sure if the server that is connected to a router is considered a broadcast domain? I only know is router divides broadcast domains and will have if it is connected to a switch with workstations. thank you.
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  • bobfromfplbobfromfpl Posts: 104Member
    We could certainly provide a topology diagram for you but I'd hate to deprive you of an educational opportunity so instead I'll google a reference for you where others are trying to learn the same topic.

    https://learningnetwork.cisco.com/thread/1734

    Hope this helps :)
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    now I understand that every device connected to the switch is counted as a collision domain but what if im going to connec my 2 server to each router? I that counted as a collision domain too?
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  • Magic JohnsonMagic Johnson Posts: 414Member
    creepted wrote: »
    now I understand that every device connected to the switch is counted as a collision domain but what if im going to connec my 2 server to each router? I that counted as a collision domain too?

    Does it specify you have to do that? Why not just connect them to the switch and if you want to separate put them in a different VLAN?
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    because I need to use 5 routers and 10 switches. I do not know that I can connect a server in a switch too.. sorry for being a noob. I always thought that server needs to be connected in a router.
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  • bobfromfplbobfromfpl Posts: 104Member
    You can certainly connect a server to a switch, at a basic level just think of a server as another device with a NIC.
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  • RouteMyPacketRouteMyPacket Posts: 1,104Member
    Easy! Step back and look at it again

    What is a "broadcast domain"? Maybe use the Routers for those, especially seeing as how we need 10 broadcast domains and have 5 routers, split them up 5/5

    What is a "collision domain"? I'd use the switches for that part...

    So there, pointers but didn't hand you anything really.
    Modularity and Design Simplicity:

    Think of the 2:00 a.m. test—if you were awakened in the
    middle of the night because of a network problem and had to figure out the
    traffic flows in your network while you were half asleep, could you do it?
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    Hi, every interface on a router is a broadcast domain, every port on a switch is a collision domain

    Check this video

    How many collision domains? Cisco CCNA - YouTube

    good luck
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    Thank you so much guys for the very useful information! I know now what design should I do. Thanks again guys!
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    how many collision domains??? 32??? you dont have 32 in there!!!!
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  • Magic JohnsonMagic Johnson Posts: 414Member
    Gngogh wrote: »
    how many collision domains??? 32??? you dont have 32 in there!!!!

    I counted 28.
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    Ok. So this is my updated layout design. Can you please help me guys tell if my topology is right or wrong? And I have one more question, should I use crossover cable or serial cable in connecting my routers? Because I am confused when connecting both routers because I saw my instructor always use serial cable when connecting router to router but we can user normal ethernet cable right?
    I am sorry I am very new to networking. I am currently taking up CCNA 1.
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    try something like this



    you can use from router to router crossover, serial or optical.

    in my topology i have 4 switches with 8 port this is equal to 32, at the center i have 6 serial connections ( 6 broadcast domains ), and then 4 switched networks ( 4 broadcast domains )
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  • ptilsenptilsen Posts: 2,835Member ■■■■■■■■■■
    Magic Johnson wrote: »
    I counted 28.
    It would be 32 once the routers are connected.
    creepted wrote: »
    Ok. So this is my updated layout design. Can you please help me guys tell if my topology is right or wrong?
    This one is quite wrong. The previous design met the need, except the routers weren't connected. This one makes no sense. Physically, almost all the devices are on the same broadcast domain.
    Working B.S., Computer Science
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    but I need to use 10 switches and 5 routers... and 16 workstations..
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    ptilsen wrote: »
    It would be 32 once the routers are connected.

    This one is quite wrong. The previous design met the need, except the routers weren't connected. This one makes no sense. Physically, almost all the devices are on the same broadcast domain.

    so on my previous design I just need to connect all the routers? I don't need to connect the switches? I am not sure if im gonna make 32 broadcast domains on my previous design if I would just connect all the routers but I will try. Thanks for your help.
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    understand what is a broadcast domain and collision domain... and then it will be easier.
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    ptilsen wrote: »
    This one is quite wrong. The previous design met the need, except the routers weren't connected. This one makes no sense. Physically, almost all the devices are on the same broadcast domain.


    every connection from router to router is a broadcast domain, broadcast's stay within the network... they are not routed.

    A broadcast domain is a network.
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    This is my latest design. Please help me count if my broadcast and collision domains are correct. It must have 32 collision and 10 broadcast domains. Thanks for all your help guys, really appreciate it :)
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    you need 4 more collisions domains
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  • ptilsenptilsen Posts: 2,835Member ■■■■■■■■■■
    Gngogh wrote: »
    every connection from router to router is a broadcast domain, broadcast's stay within the network... they are not routed.
    The routers are connected to switches which are in turn connected. Thus, all routers are on the same broadcast domain.
    Working B.S., Computer Science
    Complete: 55/120 credits SPAN 201, LIT 100, ETHS 200, AP Lang, MATH 120, WRIT 231, ICS 140, MATH 215, ECON 202, ECON 201, ICS 141, MATH 210, LING 111, ICS 240
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    Next up: MATH 211, ECON 352, ICS 340
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  • ptilsenptilsen Posts: 2,835Member ■■■■■■■■■■
    The latest design is correct. Every connection is a collision domain, even if it is also a broadcast domain (e.g., between routers). I count 32 collision domains.
    Working B.S., Computer Science
    Complete: 55/120 credits SPAN 201, LIT 100, ETHS 200, AP Lang, MATH 120, WRIT 231, ICS 140, MATH 215, ECON 202, ECON 201, ICS 141, MATH 210, LING 111, ICS 240
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    Next up: MATH 211, ECON 352, ICS 340
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    ptilsen wrote: »
    The latest design is correct. Every connection is a collision domain, even if it is also a broadcast domain (e.g., between routers). I count 32 collision domains.

    Thanks ptilsen! Got it! I got one more question in my mind.. Was it right that I used copper cross-over on connecting the routers? Or I should have used Serial DCE cable? The two cables confuses me because sometimes I saw them using serial cables when connecting routers. Thanks again! :)
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  • ptilsenptilsen Posts: 2,835Member ■■■■■■■■■■
    That would depend on the routers in question and the application. I couldn't tell that from the diagram, and I'm no Cisco expert. I just understand the concepts well. That being said, my guess would be you should have used serial cables, which is what I've always seen used for CCNA labs. Conceptually, there's no reason routers can't be connected directly by Ethernet, and I've seen it in the field, but serial seems to be what's used for these labs.
    Working B.S., Computer Science
    Complete: 55/120 credits SPAN 201, LIT 100, ETHS 200, AP Lang, MATH 120, WRIT 231, ICS 140, MATH 215, ECON 202, ECON 201, ICS 141, MATH 210, LING 111, ICS 240
    In progress: CLEP US GOV,
    Next up: MATH 211, ECON 352, ICS 340
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  • creeptedcreepted Posts: 13Member ■□□□□□□□□□
    Ok. I understand now much better. Thank you ptilsen and more power to you!
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  • networker050184networker050184 Posts: 11,962Mod Mod
    I have to say, this is probably the most useless assignment I've ever seen. Why design a network around a set number of domains rather than figure out the number of domains in a properly designed network?

    Oh well, glad you got it down though!
    An expert is a man who has made all the mistakes which can be made.
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    ptilsen wrote: »
    The routers are connected to switches which are in turn connected. Thus, all routers are on the same broadcast domain.

    every interface on the router is a broadcast domain, every interface on the router belongs to a different network, routers are used to split broadcast domains...

    broadcast to not travel from one interface to another, they are not routed, they stay within the network, do you know what a broadcast is????

    a broadcast is a arp request for something... arp request are not routed!!!

    no two routers are in same broadcast domain even if they are in the same building.

    if you have two routers connected by a switch those interfaces are in the same broadcast domain, but the other interfaces of a router are not..



    Broadcast domain

    A broadcast domain is a domain in which a broadcast is forwarded. A broadcast domain contains all devices that can reach each other at the data link layer (OSI layer 2) by using broadcast. All ports on a hub or a switch are by default in the same broadcast domain. All ports on a router are in the different broadcast domains and routers don't forward broadcasts from one broadcast domain to another.

    The following example clarifies the concept.



    ptilsen wrote: »
    This one is quite wrong. The previous design met the need, except the routers weren't connected. This one makes no sense. Physically, almost all the devices are on the same broadcast domain.



    in this example there are 8 broadcast domains

    check this video

    How many collision domains? Cisco CCNA - YouTube

    you should try a learn more about broadcast domains!!!! i think you dont understand the concept well, when you say all routers are in the same broadcast domain.
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  • ptilsenptilsen Posts: 2,835Member ■■■■■■■■■■
    Wow. I'm not sure I can help how incorrect your understanding is, but I'll try. Routers on the same logical switched network are on the same broadcast domain, period. The switches in that diagram are connected to each other. That they are also connected to routers does not magically separate their broadcast domains. There are six broadcast domains in the pictured network, five between each router and one with every single device. Nothing needs to get routed to go from any router to any other router, because they are all connected by switches.

    Edit: Just to ensure there's no ambiguity about which diagram I'm referencing, it's this one:
    http://www.techexams.net/attachments/forums/ccna-ccent/4614d1387298890t-designing-network-10-broadcast-domains-32-collision-domains-pls-help-me-network-design3.jpg
    Working B.S., Computer Science
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    Next up: MATH 211, ECON 352, ICS 340
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  • GngoghGngogh Posts: 160Member ■■■□□□□□□□
    ptilsen wrote: »
    Wow. I'm not sure I can help how incorrect your understanding is, but I'll try. Routers on the same logical switched network are on the same broadcast domain, period. The switches in that diagram are connected to each other. That they are also connected to routers does not magically separate their broadcast domains. There are six broadcast domains in the pictured network, five between each router and one with every single device. Nothing needs to get routed to go from any router to any other router, because they are all connected by switches.

    you dont know that you are wrong, but ill try once more to clarify your understanding of broadcast domains.. this time i have ilustrated the diagram for you to see how many broadcast domains there are.



    and there are 8!!!
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  • networker050184networker050184 Posts: 11,962Mod Mod
    Yeah, I see eight as well assuming it's a single VLAN.
    An expert is a man who has made all the mistakes which can be made.
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  • ptilsenptilsen Posts: 2,835Member ■■■■■■■■■■
    Gngogh wrote: »
    you dont know that you are wrong, but ill try once more to clarify your understanding of broadcast domains.. this time i have ilustrated the diagram for you to see how many broadcast domains there are.



    and there are 8!!!
    I have not disputed that there are eight broadcast domains. You're missing my point entirely. All routers except 0 are members of BC 1 in this diagram, which is a nonsensical design (outside of using VLANs, which are not represented here). That is my point. Of course there are additional broadcast domains between each router, but my point is that the routers (except 0) all have one interface that is on the same broadcast domain as all the others, which again, makes very little sense.
    Working B.S., Computer Science
    Complete: 55/120 credits SPAN 201, LIT 100, ETHS 200, AP Lang, MATH 120, WRIT 231, ICS 140, MATH 215, ECON 202, ECON 201, ICS 141, MATH 210, LING 111, ICS 240
    In progress: CLEP US GOV,
    Next up: MATH 211, ECON 352, ICS 340
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