Broadcast Collision Domains?

Eagle710

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HI i was trying to figure out the difference but i can seem to find a good definition of either of these terms. Broadcast Domain .... Collision Domain. I have been trying to learn it but it wont make sense to me when i read it off Google searches. Anyone can please offer me some help with a nice easy to understand definition please. I would appreciate it.

Eagle710
 

celticfan11

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HI i was trying to figure out the difference but i can seem to find a good definition of either of these terms. Broadcast Domain .... Collision Domain. I have been trying to learn it but it wont make sense to me when i read it off Google searches. Anyone can please offer me some help with a nice easy to understand definition please. I would appreciate it.

Eagle710

Imagine you have a the following setup

.........Router
........../.....\
....switch...switch

there are 2 broadcast domains in the above crude diagram, because layer 3 devices(routers) DO NOT forward broadcasts. Only layer 1 (hubs) and layer 2 (switches) do. A Broadcast domain is only segregated by a layer 3 or higher device that will not forward the broadcasts. So Each switch is its own broadcast domain. Make sence?

A collision domain, is basically non exsistant today. Basically it is any segmant where collisions can happen. You cannot have collisions on a layer 3 device or a layer 2 device. So each port on a switch is a collision domain. a layer 1 device (hub) WILL be a big collision domain because packets can cause collisions due to i want to say being half duplex. I think i am wrong there. But a 24 port switch will have 24 collision domains.

Hope i helped.
 

fitz

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A collision domain, is basically non exsistant today. Basically it is any segmant where collisions can happen. You cannot have collisions on a layer 3 device or a layer 2 device. So each port on a switch is a collision domain.

....

But a 24 port switch will have 24 collision domains.

Well, to be a little more particular, as each collision domain is a segment, a port is not a segment, the segment would be the connection from one port to another port on a switch, meaning, each port on a 24 port switch could technically take part in up to 23 collision domains (1 collision domain for each "segment" to the other ports on the switch) :p
 

Eagle710

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Broadcast Domains i get but im stilling have difficulty understanding which devices allow or cause collision domains?? Thanks all for your tutoring lessons.
 

fitz

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Basically, only a hub will allow a collision domain. Generally, who uses hubs anymore? Don't use a hub.. buy a switch..
 

celticfan11

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im assuming this is for school.....
a Hub = one big collision domain.
a switch = Many collision domains
 

fitz

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and in this case, one big collision domain is a bad thing..
 

Eagle710

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im assuming this is for school.....

Yeah this is for school i got Cisco test coming up and the stupid book doesn't explain these details very good. So i thought i would Google which didn't settle properly in my head but OSNN did so.... Thank you
 

X-Istence

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Yeah this is for school i got Cisco test coming up and the stupid book doesn't explain these details very good. So i thought i would Google which didn't settle properly in my head but OSNN did so.... Thank you

Cisco test eh? Good luck!
 

Eagle710

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Did the test and thanks to your help with BCs and DCs help i was able to answer the question... of course doesnt mean i got it right. LOL... we will see in two weeks. Thanks again all
 

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