Collision domains
Jasiono
Member Posts: 896 ■■■■□□□□□□
in CCNA & CCENT
Reading this book, I stumbled across my confusion again that haunted me in the past in regards to collision domains.
I know switches break up collision domains within broadcast domains.
Say that I have the following setup:
Switch A
Switch B
Switch C
Router 1
PC1
PC2
Router 1 is connected to Switch C
Switch C connects to Switch A and B
PC1 is connected to Switch A
PC2 is connected to Switch B
Does this mean I have 5 collision domains?
1 for the connection between the router and switch C
1 for the connection of switch C being connected to switch A
1 for the connection of switch C being connected to switch B
1 for the PC being connected to Switch A
1 for the PC being connected to Switch B
So basically, to my understanding now, is that each PORT on a SWITCH creates a collision domain. Is that a safe assumption?
I know switches break up collision domains within broadcast domains.
Say that I have the following setup:
Switch A
Switch B
Switch C
Router 1
PC1
PC2
Router 1 is connected to Switch C
Switch C connects to Switch A and B
PC1 is connected to Switch A
PC2 is connected to Switch B
Does this mean I have 5 collision domains?
1 for the connection between the router and switch C
1 for the connection of switch C being connected to switch A
1 for the connection of switch C being connected to switch B
1 for the PC being connected to Switch A
1 for the PC being connected to Switch B
So basically, to my understanding now, is that each PORT on a SWITCH creates a collision domain. Is that a safe assumption?
Comments
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d4nz1g
Member Posts: 464
Yes, each port on a switch is a collision domain.
In theory, every shared medium (like a hub, for example) is a collision domain.
Regarding to broadcast domains, each VLAN represents a broadcast domain since a broadcast is destined to every host connected to a given switch (or vlan). So in a switched environment, you will have a broadcast domain for each vlan. -
Jasiono
Member Posts: 896 ■■■■□□□□□□
Ok, so based off of what you said and searching further into it, finding out that routers also break up collision domains, I attached a diagram I quickly put together and came up with the following:
24 Collision domains
8 broadcast domains
Is that correct?
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d4nz1g
Member Posts: 464
20 collision domains, actually.
The collision concept only exists in ethernet. -
Jasiono
Member Posts: 896 ■■■■□□□□□□
Ok so basically what is being said here is that if a router is connected to another router, only count that as a broadcast domain and not a collision domain because it's not connected to an ethernet port on a switch, yeah?
That is where my confusion comes in.
A switch to a router is a collision domain but a router to a router is not.
Thanks for the time in explaining this to me, I really appreciate it. -
tecnodog7
Member Posts: 129
20 collision domains, actually.
The collision concept only exists in ethernet.
Ok i counted wrong, yes it's 20 :P -
theodoxa
Member Posts: 1,340 ■■■■□□□□□□
R&S: CCENT → CCNA → CCNP → CCIE [ ]
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seigex
Member Posts: 105
Circled in red is what I counted as a collision domain.
Unless I'm missing something, bridges are L2, and separate collision domains. So it would be 21 by my count -
tecnodog7
Member Posts: 129
I'm counting 21.
Damn you and your counting skills
.
Yes it is 21 since there's a Bridge in the middle which i mistook for a HUB. Doh!!!!!!! -
Jasiono
Member Posts: 896 ■■■■□□□□□□
I just did connections, nothing radical or fancy. There is nothing configured on anything.
