Talk:Broadcast domain

message: Jan 26, 2014
Joe Stanaback.
This is further proof, yes proof that the Broadcast Domain is determined by the Layer 3 Internet Protocol. 
https://support.microsoft.com/kb/169289
Microsoft's explanation of DHCP and DHCPdiscovery Internet Protocol. 
DHCPdiscovery Internet Protocol broadcasts to broadcast address 255.255.255.255.
Now what does the mean?.  What is the subnet address, network address, subnet mask, boardcast address, broadcast domain?
Well first all broadcast addresses are Layer 3, other wise they would not use IP addresses nor would they be defined by an IP address.  IP is OSI Layer 3.  IP is Internet Protocol, specifically IPv4.  IP address are declared and defined by the Layer 3 Internet Protocol, not by of the Layer 2 protocols.  I dare you to try to prove it otherwise.
Read the article by Microsoft, https://support.microsoft.com/kb/169289 on DHCP.  It clearly notes INTERNET PROTOCOL !!
Now back to "What does this mean?"  DHCPdiscovery Internet Layer 3 Protocol broadcasts to IP address 255.255.255.255.
Again, what is the network address, the subnet mask, the "Broadcast Domain?"
Simple:
The Subnet is   0.0.0.0./0
The network address is 0.0.0.0.
The broadcast address is 255.255.255.255. 
The broadcast domain consists of the range of IP address from 0.0.0.1 trough 255.255.255.254
The broadcast domain consists of all the IP addresses the make up the entire Internet, excluding the first and last. 
This means the DHCPdiscovery protocol will broadcast of each and every address, and subnet, that makes up the entire Internet.  This makes it impossible for the DHCPdiscovery Layer 3 Internet Protocol not to be able to find a DHCP server.  Because routers open, read, identify and dicard broadcast messages, the DHCPdiscovery Layer 3 Internet Protocol broadcast is confined to the local Internet Subnet operating atop of the local area network.  OH... more proof, I a router, operating layers 1, 2, and 3, open an IP packet only to discover it is an IP broadcast message and discards it, obviously Broadcast message are LAYER 3.  The router, not the LAN hardware, is want actually prevents Broadcast messages from transversing IP Subnets.  It the router is blocking broadcast, obviously broadcast messages are layer 3.   Come on guys, figure it out. 
Once the DHCP server is found, the node broadcasting the DHCPdiscovery address is configured with the LOCAL INTERNET SUBNET information.  People need to realize that the Internet is subnetted into subnets, or local subnets, that operate atop of LANs.  A lot the concepts that people mistake as LAN Layer 2 only are actually Layer 3 concepts and protocols operating atop of the LAN.  
The Boardcast Domain is defined by the Layer 3 Internet Protocol, not by any of the currently or previously used Layer 2 protocols.  Ethernet does not, PPP does not, ATM does not, NetBEUI does not.  If you can prove me wrong, I dare you to.  Name the protocol and addressing scheme used and methods used.  What is the layer 2 broadcast address? How is the layer 2 Broadcast Domain declared?  You will find no layer 2 information on this.  
Also read up on the Internet Engineering Task Force Request for Comments.  This one explains Internet Protocol Broadcasting and Broadcast Domains.  Note the subject matter, Internet; a Layer 3 Protocol. http://tools.ietf.org/pdf/rfc3069.pdf
Broadcast Domains are also defined in other Request for Comments that cover the development of the Internet back to 1968. 
Do you need more proof ?????  Read more of the examples that I have below that clarify what a Broadcast Domain is.  This current page on wikipeda on Broadcast Domains is inaccurate and the disinformation is bad for anyone trying to learn networking concepts and it is also very bad for the INTEGRITY of wikipedia itself.
SHAME SHAME !!   
Jan 25, 2014
Joe Stanaback
My update attempts, which by the way are correct. 
Who ever wrote this page is confused about what a "Broadcast Domain" is. 
"Broadcast domain" refers to a subnet network, such as 192.168.1.0/24, which has the broadcast address of 192.168.1.255.  "Broadcast domain" refers to all that is within the broadcast range, or all IP addresses that will receive a broadcast message within the Internet Protocol subnet.  That means everything within the 192.168.1.0/24 subnet.  Subnetting and Boardcast domains pertain to the OSI Reference Model Layer THREE.  The "Broadcast domain" is not in reference to MAC addresses.  MAC addresses are OSI Layer TWO.  
The Broadcast domain is identified by the broadcast address, which in turn is identified by the SUBNET MASK.   The broadcast address is an Internet Protocol address.  Internet Protocol is OSI Layer THREE. 
The Broadcast domain is OSI Layer THREE not TWO.  If it was layer TWO, it would have a MAC address not a LAYER THREE INTERNET PROTOCOL ADDRESS. 
 
The "Subnet" is 192.168.1.0/24
The "Network Address" is 192.168.1.0
The "Broadcast Address" is 192.168.1.255.
The "Broadcast Domain" is IP addresses 192.168.1.1 through 191.168.1.254
 
The "Broadcast Domain" is the range of IP addresses that will receive a broadcast message.  It is also the list of IP addresses that can be assigned to device nodes; from 192.168.1.1 to 192.168.1.154.  NOTE THE WORD IP!!  Internet Protocol.  IP is LAYER THREE not TWO!!
This is why the first address and the last address are never assigned to a computer.  The first address is the network, or subnet address, and the last address is the broadcast address.  The "Broadcast Domain" refers to all IP addresses that can be assigned to nodes that can will receive a "broadcast" message within the subnet or Broadcast Domain.  
Another example:
Subnet:     131.247.168.0/23
Network Address:  131.247.168.0
Subnet Mask: 255.255.254.0
Broadcast address: 131.247.169.255
Broadcast Domain:  IP Addresses 131.247.168.1 through 131.247.169.254  
Another example: 
Subnet:   131.247.168.128/25
Network Address:  131.247.168.128
Subnet Mask: 255.255.255.128
Broadcast address: 131.247.168.255
Broadcast Domain:  IP Addresses 131.247.168.129 through 131.247.168.254
Subnetting deals with the Internet and the Internet Protocol ( IP ).
That means, Broadcast domains are LAYER THREE of the OSI Reference Model, not layer two.  Also, do not confuse LAN with Broadcast domains.  Layer 2 LANs deal with the Ethernet Protocol and with Layer 1 specifications.  
A single cable connecting ComputerA and ComputerB is a LAYER 1 network.  This also identifies what is called a Collision Domain.  Collisions Domains are Layer 1, not Layer 2.  This ONE SINGLE cable connecting two computers is a collision domain and a Layer 1 Network.  It cannot get any more simple or easier to understand than is example right here. 
Often LANs are incorporated into a subnet of the Internet. Plus, know that the local IP Layer 3 subnet functions atop of a Layer 2 and Layer 2 fucntions atop of Layer 1.  But know what protocol function at which layer.   
Layer ONE -->> A cable connecting ComputerA and ComputerB. 
Layer TWO -->> The NIC card that has a Layer 2 MAC address. 
Layer THREE -->> The NIC care in each computer that has an IP address.
The CABLE can ONLY function at Layer ONE, while the Network Interface Card (NIC), in each computer, functions at Layer 1 ( It sends and receives electrical transmissions, it is a TRANSCEIVER) and at Layer 2 ( It is configured with a Layer 2 Ethernet Hardware MAC Address ) and at Layer 3 ( It is configured with a Layer 3 Internet Protocol Address, so it knows its IP address and subnet mask and the IP Broadcast Address and IP Broadcast Domain. )
Layer THREE -->> IP. IP protocol 
Layer TREEE -->> IP subnet 192.168.1.0/24
Layer THEEE -->> subnet mask 255.255.255.0
Layer THREE -->> Broadcast address 192.168.1.255
The OSI Layer THREE Broadcast domain includes all IP addresses from 192.168.1.1 to 254.
ARP maps Layer THREE to Layer TWO -->> Ethernet.  802.3 Protocol.  
ARP maps IPv4 addresses to MAC addresses. 
For example:
ARP might map IPv4 address 192.168.1.1 to MAC address F0:4D:A2:F4:6F:39.  This allows a Broadcast Domain node assigned IP address 192.168.1.1 to be received Layer 2 Ethernet messages sent to MAC address F0:4D:A2:F4:6F:39.
When a broadcast message is sent to the Broadcast Domain via IP Boradcast address 192.168.1.255, one IP address that it reaches is IP address 192.168.1.1, which is mapped to MAC address F0:4D:A2:F4:6F:39 via ARP with a switch. But Broadcast Domains are established by the SUBNET MASK ADDRESS of the Internet Layer, not the Data-link Layer.  
Oh, a switch functions at Layer 1, Layer 2, and Layer 3.  How is that possible? THINK, figure it out.  Why does the NIC in ComputerA also function at Layer 1, Layer 2, and Layer 3?  Does a switch send and receive electrical impulse or signals? YES or NO? If yes, it is a Layer 1 device.  Does a switch have an assigned Layer 2 Ethernet Hardware MAC address? Yes or No?  If yes, it also operates at Layer 2.  WOW! That took some thinking.  Does a switch have the ability to be assign a Layer 3 Internet Protocol Address and does it use ARP and ARP table to manage and map Layer 3 IPv4 Addresses and Layer 2 Ethernet MAC Addresses? Yes or No?  If yes, than it is also operating at Layer 3.  
HUBS are not assigned Layer 3 Internet Protocol Addresses. Do HUBS have assigned Layer 2 MAC addresses?   Can you telnet to a hub?  What is telnet?  What layer does  telnet operate at?  How about OSI Layer 7.  Can you telnet to a switch?  Well, apparently a switch is able to function at Layers ONE through SEVEN it you can telnet to it.  In fact, in order to telnet to a switch, it actually has to a telnet server running on it. Or SHH, if you used SSH to access it. At what layer does a telnet or ssh server operate?  
Broadcast domains are determined by Internet subnetting and the subnet mask address. 
You guys are getting confused and are mixing up LAN protocols with IP protocols and addressing schemes and you are thinking they are all the same.  The Broadcast Domain is not defined by the Local Area Network (LAN), nor by any Layer ONE or Layer TWO protocol.  The Boardcast Domain is defined by Internet Protocol and by subnetting and by the subnet mask with determines the Broadcast address and the range of IP addresses that are within the Broadcast Domain.  
The REFERENCES below to what a Broadcast Domain is are all wrong.  
Plus, a LAN segment is and Ethernet segment, which is a patch cable or a 10Base2 or a 10Base5 coaxial cable that connects a node.  The cable from a switch to a network interface card is an example of a LAN segment.  That cable from a switch to a network interface card on a server on rack can also be an isolated collision domain.  Look online and read up on Request for Comments.  The is the real stuff!
http://www.faqs.org/rfcs/  
Or try the Internet Engineering Task Force at http://www.ietf.org/rfc.html
The stuff on this page is misleading and is incorrect.
This ends my talk on improving wikipedia, with wikipedia does not seem to be interested.  I guess I will just not donate any longer.  That saves me money. 
Joe  
Oh... Someone had a question just below about Algorithms to solve collision domains.  No there are none.  But the issue with collisions has been solve by isolating collision domains via ARP Tables used by switches. See I am still trying improve wikipedia by answering someone else's question.  OH... Collision Domain are Layer 1 not Layer 2.
Proof?  How about something simple!
Removal all cable and hubs and switches from your net and take a single Ethernet cable and use it to connect two computer.  PRESTO you have a Layer 1 Collision Domain used by two computers to transmit electrical signal back and for forth between one another.  Collision Domains are Layer 1, the Physical Layer.  The page on Collision Domain is also inaccurate and misleading!
Joe Stanaback
 — Preceding unsigned comment added by Indirsgame (talk • contribs) 07:47, 26 January 2014 (UTC)
replies: text: There are methods solving collision problems on networks, have a look at CSMA and its variants - CSMA/CD nad CSMA/CA being most commonly used. Please make sure you include your signature to your discussion posts (four tildes in a row). 84.47.47.221 01:50, 15 January 2006 (UTC)

text: No, please read up on layer 2. A broadcast domain is the domain of nodes that are addressed by a layer 2 broadcast – a destination MAC of all 1s (on Ethernet). You're mixing it up with layer 3 broadcasts and directed broadcasts. Additionally, this article is not talking about collision domains. Collision domains can be connected by switches/bridges, broadcast domains by routers. Zac67 (talk) 11:21, 26 January 2014 (UTC)
thread_title: Untitled

message: ONOS and Floodlight apparently use Broadcast Domain Discovery Protocol (BDDP). As this relates to Broadcast domain, I would expect it to be at least mentioned, if not discussed or explained, in this article. I also note there is no separate article for BDDP. Can someone please resolve this? Thanks in advance for your anticipated help. 167.98.51.116 (talk)  —Preceding undated comment added 09:45, 9 January 2020 (UTC)
replies: text: Feel free to start a Broadcast Domain Discovery Protocol article (assuming notability) or possibly List of broadcasting protocols, but we cannot reasonably list all protocols here that use broadcasting, not even prominent ones like ARP or DHCP. --Zac67 (talk) 17:52, 9 January 2020 (UTC)
thread_title:  Broadcast Domain Discovery Protocol (BDDP)