13 - Collision domain & Broadcast domains Flashcards
what is a Collision Domains ?
Its part of a network where packets collision occurs due to multiple devices trying to communicate ( send packet at same time )
How many Collision Domains do each of these devices have ?
- Hub
- Bridge
- Switch
- Router
Hub = 1 Bridge = only 4 port & each is a collision domain Switch = Every 26 to 48 ports are a collision domain Router = Every port, so 2
what is a Broadcast Domains ?
A broadcast allows devices to reach all devices on the same broadcast domain at the data link layer of OSI.
If you shout there has to be a border to where the shouting ends, this border is defined by a broadcast domain.
The shouting is known as a broadcast when devices try to reach out to another device
How many Broadcast Domains do each of these devices have ?
- Hub
- Bridge
- Switch
- Router
Hub = 1 Bridge = 1 switch = By default it is 1 router = 2 broadcast domain. Each interface on a router is a Broadcast domain.
If switch connected to the router = 1 broadcast domain. Router 2nd interface is another broadcast domain.
What is a Vlan
Vlans helps break up broadcast domains into multiple logical groups.
We can then assign Devices into that logical group.
This is done by assigning ports to Vlans
What are the Max Vlans allowed ?
Are Vlans only broadcasted on to 1 switch ?
even if it is connected to several switches ?
Maximum = is 4096
- A broadcast will reach every device on all switches that are on the same vlan
e. g vlan 15, all devices across 4 connected switches will hear the broadcast if on the same vlan
Tell us about Vlans ?
Vlan facts to know
- Vlans range from 1 - 4096
- each vlan is a separate network (broadcast domain)
- each vlan will require their own subnet - different to other vlans
- this helps access control, and we can configure quality of service to priorities one vlan over another.
