Hot Downloads



The forum is in read only mode.
Welcome, Guest
Username: Password: Remember me
  • Page:
  • 1

TOPIC: Broadcast and Multicast basic concepts

Broadcast and Multicast basic concepts 14 years 11 hours ago #8162

  • thorpe
  • thorpe's Avatar Topic Author
  • Offline
  • Frequent Member
  • Frequent Member
  • Posts: 45
  • Thank you received: 0
I have been reading the section on Data Transmissions and I am having an issues with a basic concept.

The page on broadcasts states:

A Broadcast means that the network delivers one copy of a packet to each destination. On bus technologies like Ethernet, broadcast delivery can be accomplished with a single packet transmission.

Does this mean if I had 50 machines in my broadcast domain that

A) the sender would send 50 packets


B) the sender would send 1 packet and the 50 machines would copy the packets when it arrives and then send on the original packet.

Further to if I had a multicast group in my 50 machines with only 2 machines taking part in the multicast group would

A) the sender send 2 packets of data


B) the sender would send 1 packet and the 2 machines would copy the packet and send on the original


Re: Broadcast and Multicast basic concepts 13 years 11 months ago #8169



Sahir Hidayatullah. Staff - Associate Editor & Security Advisor

Bcast 13 years 11 months ago #8181

Sahir's right. Every packet sent onto an Ethernet segment is seen by all the stations. However every station ignores it except the one whose MAC address matches the destination MAC address in the packet. This is unicast. With broadcast, the packet is given a special MAC address (all the FF's) which tells every station to accept and process it regardless. So there's just one packet sent but everyone pays attention. Analogy - Go into a crowded shop and call "Fred" and only Fred will turn round. But yell "Fire" and everyone will pay attention. Multicast is similar except it's the multicast group rather than all the stations that pay attention to the packet.
  • Page:
  • 1
Time to create page: 0.099 seconds


Cisco Routers

  • SSL WebVPN
  • Securing Routers
  • Policy Based Routing
  • Router on-a-Stick

VPN Security

  • Understand DMVPN
  • GRE/IPSec Configuration
  • Site-to-Site IPSec VPN
  • IPSec Modes

Cisco Help

  • VPN Client Windows 8
  • VPN Client Windows 7
  • CCP Display Problem
  • Cisco Support App.

Windows 2012

  • New Features
  • Licensing
  • Hyper-V / VDI
  • Install Hyper-V


  • File Permissions
  • Webmin
  • Groups - Users
  • Samba Setup