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broadcast and multicast

jonk34567
Level 4
Level 4

Are broadcast and multicast limited to subnet ? 

6 Replies 6

josef.kokal
Level 1
Level 1

Broadcasts are limited to a so called broadcast domain.

These Broadcast domains are limited by their subnet/vlan or routers.

br

josef

Leo Laohoo
Hall of Fame
Hall of Fame

Stop spamming the forum with single-topic threads.  Put all your questions in one big thread. 

Specify the purpose of the questions if they are for school work or otherwise.  The reason behind this are two-folds: 

1.  A professor or instructor can tell if the answer is copied somewhere and may he/she might find ways to verify if you are a "hidden genius" or a plagerist. 

2.  What happens in the "wild" and what happens behind text books are two different things:  Text books might give you what happens in an "ideal world" and this is what the instructor wants.  If he/she finds answers that do not comply with text book materials one might not like the grades handed back.

i can post all questions in single thread because they are from diffrent topics

Joseph W. Doherty
Hall of Fame
Hall of Fame

First, broadcasts and multicast are usually not network specific, they, by default, are limited by the broadcast domain.  Subnets and broadcast domains are often configured 1:1, but they don't have to be.

For example you could have a broadcast domain containing both 192.168.1.0/24 and 192.168.2.0/24.  Hosts on those networks would, by default, see both broadcasts and multicast sourced from any host on either subnet.

There's also general broadcast and directed broadcast. The latter is routed to a destination subnet and treated as a broadcast there.  For an example of the latter, if you were on subnet 192.168.1.0/24 and pinged 192.168.2.255, hosts on 192.168.2.0/24 would receive the ping.

Multicast is often multicast routed to multiple subnets.  The latter, like unicast routing, requires a configuration setup.  Without it, multicast is limited to its source broadcast domain.

how to configure a broadcast domain to have more than 1 subnet

Have hosts with different subnets connect to the same hub, dumb switch, or VLAN.

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