Trying to understand multicasting from the client/host perspective ..
What client software is needed? What configurations are required? Is there web based client, and any configuraton required? How a client start using a typical multicast service? How does a client/host works behind the scene to get multicast service, in conjunction with what have been set up on the router and switch?
Any good reference on this, I mean from client/host perspective, or something that provide the"whole" picture, including protocol, router, switch, and client/host?
If the multicasts need to be sent to multiple LANs, you need multicast-enabled routers.
Client for what? Multicasting is a general-purpose mechanism, not a single application.
If it's transmitting, it just sends messages to the multicast address. Multicast routers take care of sending to all the members of the group.
If it's receiving, it "joins" the multicast address. This involves sending out a message that the local router receives, so that it can inform other multicast routers that there's a member on this LAN and they'll forward messages here.
Do a google search for multicast routing protocols.
A "user guide" implies a particular application, not a general technology. Your question is like asking for a user guide for TCP/IP, as opposed to Internet Explorer.
I would say you are not guessing very well today. I suggest you re-read the patient and thoughtful responses responses you've received and try to make them apply to your situation.
I look forward to hearing your posts from the 5th grade.
ok .. what I'm asking is how the technology works from a client perspective..here are too many people know how it work from the router ans switch sides.
Ok. Speaking on "4th grade language", multicast is like a radio. There are a radio waves (IP addresses in the 224.0.0.0-239.255.255.255). Each wave (IP address) is an individual "radiostation", where there is one Speaker (Radio Translation Station), and multiple Receivers (Radio receivers). To be able to listen the "station", your "radio" should be tuned to proper frequency (listen proper IP address). There are some "standard defined" stations (mostly in 224.0.0.0-224.0.0.255 range), used for specific needs (routing protocols, etc.). But some applications can send multicast traffic for their own needs. For example, you may multicast a radio or video, you may multicast software updates or application data. In most cases "Sender" is not aware if there are any listeners - multicast just goes out. When "receiver" wants to "subscribe" to certain "frequency", it sends special "Join" request to local switch and router. Router then examines, if it already has "the subscription", or, if not, if any neighbor has "subscription" to this "frequency". If it's possible to find "bandwidth", all routers on the way between "Sender" and "Receiver" keep the subscription. When "Receiver" does not want to receive the frequency, it sends a special "Leave" message, and routers, if there are no more "Subscribers" for this particular frequency, remove it from the route.
Multicast, as I described, is "one-way traffic". So, to use it, you should have the multicase sender, your should know the multicast IP address, used by sender, and have an application, which should receive this traffic. One example, how you may use it. Install Windows 2000/2003 Server with Media Streaming Server. Create specific Media Source (for example, convert a couple MP3s into the Media), and define it as a Multicast. Then use specific URL to pont your Microsoft Media Player to this Media. the communication between your Server and multiple workstations will be through Multicast.
Are you asking how to write multicast applications, implement a multicast network infrastructure, or what multicast applications exist and how to use them?
Mike, thank you very much for the excellent explanation .. you explan things just like my favorite teacher.
I guess when I join a webinar, once I got on the site, the step I was authenticated is also the process I was joining the group - if I understand a webinar is a multicasting session correctly?
As a result I'll also get aother MAC address, besides the > > Trying to understand multicasting from the client/host perspective .. > >
Mike, thank you very much for the excellent explanation .. you explan things just like my favorite teacher.
I guess when I join a webinar, once I got on the site, the step I was authenticated is also the process I was joining the group - if I understand a webinar is a multicasting session correctly?
As a result I'll also get aother MAC address, besides the > > Trying to understand multicasting from the client/host perspective .. > >
Webinar may go by Multicast, but most likely it will go by Unicast. In case of Unicast, the "Publisher" opens one stream for each individual "Subscriber". Why Multicast is not used everywhere? Most (if not every) firewalls are not aware or do not honor Multicast. So, to ensure that all recipients are able to receive a Webinar, Publishers usually either do "try Multicast, then do Unicast". Plus, if one router in the path between "Source" and "Receiver" will not understand Multicast, whole "subscription" will fail.
Multicast could be used within one ISP's network, where they control every router and swtich in the network. Then ISP can put, for example, TV channels, each in the individual "bandwidth". This will allow them to put better quality Video with lower Bandwidth utilisation (you may have thousands recipients, but your bandwidth will stay the same). To avoid problems with user's firewalls, they usually "drop" this multicast directly from their DSL or Cable modem into the "decoder box".
Practical use for multicast today is limited by local LAN boundaries or MAN/WAN networks if you have control over your equipment. At the local level (access switches), multicast either converted to a Broadcast (if switch does not understand Multicast), or, if switch is "multicast-aware", it goes only to specific ports on the switch, where "subscribers" reside.
Conversion from the specific Multicast IP address to a special MAC addresses happens on the "last router". When multicast packet reaches the last router before the client, router, prior to put the frame to the switch, converts it to a special MAC address. And the switch will either treat this frame as a broadcast and send to all ports, or will determine, which port should receive this frame and will send it to specific port(s).
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Nitpick. No actually it's more than a nitpick. There is a class of applications, like multicast TV, which work that one-to-many way and there is a developing technique called source specific multicast (SSM) which enforces it, but it's a refinement. In general any system can send traffic to a multicast group address and some applications (conferencing, monitoring applications) require multiple senders.
The multicast traffic will be sent to a multicast MAC address. If your system joins the group then it will receive traffic sent to that MAC address, but you won't "get" the address as such.
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