Heres another one for you, but a question that seemed to cause me a lot of headache in my CCNA part 1.
Theres a network with one router, two switches hanging off it on two Fast Ethernet interfaces, and then off both switches a bunch of hosts hanging off that. The question was "assuming there is only on native Vlan (Vlan1), how many broadcast domains / collision domains are there?"
Now forgetting the actual numbers here. Does anyone have a straightforward and good explanation of the definition of a broadcast and a collision domain? I know it is a basic question but I think this would prove useful to many people starting out.
if i have understand correcly the diagram you will have 2 broadcast domain and as many connection the switch has for collision domain.
Ok thanks, so in the diagram below, there would be 2 broadcast domains (seperated at the router) and then 6 collision domains, or 8 collision domains (i.e. do you count the link from switch to the router as a collision domain too?
Based on the diagram provided, then it would indeed be 2 Broadcast domains and 8 Collision Domains. Basically every port on a switch is its own collision domain.
first of all, sorry for my English, I'm from France.
There are 8 collision domains, one per pair of devices connected to each other (switch to router, switch to swich, switch to computer etc...) since we are talking about layer 1 concept (physical connection).
Each port on a switch is a separate Collision Domain... Hense a 24 port switch has potentially 24 Collision Domains.
A Hub has a single Collision Domain regardless of the number of ports.
Considering the firs question here and the diagram..... we have two broadcast domains because the router has two "LANs" connected to it. What does the VLAN have to do here? Can the VLAN be considered as a 3rd broadcast domain?
what is it mean exactly the word " colison domain" & "brodcast domain" ?? what happen exatcly with data or frame or packet?
Broadcast domain is the set systems that will receive a broadcast when sent by a single system. Broadcast domains are always (well usualy!) separated by a route since a router doesn't propogate broadcasts. So in the scenario of a router with two non-connected switches, there are two broacast domains (that seen by switch1 and the other seen by switch 2).
Collision domain is that set of systems in which a CSMA type collision can occur. WIth switches, each port is it's own collision domain.
same segment to pay attention to it.
A group of Ethernet or Fast Ethernet devices in a CSMA/CD LAN that are connected by repeaters and compete for access on the network. This situation is typically found in a hub environment where each host segment connects to a hub that represents only one collision domain and only one broadcast domain.
must retransmit at a later time.
busy, the computer waits and listens.
Both computers that attempted to transmit must back off, wait a random period of time, and then attempt to transmit again.
the corrupted frames (called runts).
member of the same broadcast domain. Routers and other higher-layer devices form boundaries between broadcast domains.
I hope above information helps..
There's a collision domain between each host and the respective switches, as well as between the switches themselves. So each individual link is a collision domain.
The broadcast domain would be defined by your vlan scope.
Originally all the PC were connected along a piece of co-axial cable so Ethernet could collid. We split these cables with bridges to reduce the collisions but a PC would broadcast to all the PC even on the other side of the bridge.
Eventually each PC had its own cable to the hub so the PC could only collid with the hub port and eventually we moved to full duplex hubs called switches. You could still broadcast to every PC attached to the switch.
Collisions still occur with wireless but that is a different story.
In this diagram, there would be 9 collisions right?