![]() This is the normal source address used by an interface for completing the MAC source address field, and also a filter for received frames.Ī computer sends all packets which it creates with its own hardware source address, and receives all packets, which match its hardware address or the broadcast address. Interface card is allocated a globally unique 6 byte MAC source address when the factory manufactures the card (stored in a PROM). The hardware address is also known as the MediumĪccess Control (MAC) address, in reference to the IEEE 802.x series of standards that define Ethernet. The MAC destination address (all 1 s) is used to identify a broadcast packet (sent to all connected computers in a broadcast domain) or a multicast packet (lsb of 1st byte=1) (received by a selected group of computers). The Ethernet network uses two hardware addresses which identify the source and destination of each frame sent by the Ethernet. Most modern network interface cards implementĪ set of multicast filters, relieving the host of the burden of (promiscuous mode) and perform software filtering to remove all Performance penalty by forcing the adaptor to receive all packets The earliest LAN network interfaceĬards had no specific support for multicast and introduced a big (using hubs/repeaters) inherently support multicast, since allĬards connected to the LAN. Ethernet)Īre able to support the multicast transmission mode. Savings (up to 1/N of the bandwidth compared to N separate unicast There is a common need for the same data required by a group ofĬlients, multicast transmission may provide significant bandwidth The multicast mode is useful if a group of clients requireĪ common set of data at the same time, or when the clients areĪble to receive and store (cache) common data until needed. ![]() The network for which there are no active clients. Sub-networks have active clients for each multicast group andĪttempt to minimise the transmission of packets across parts of The routers in a multicast network learn which Membership of a group is dynamic andĬontrolled by the receivers (in turn informed by the local clientĪpplications). Only if they have previously elect to do so (by joining the specific Unlike broadcast transmission (which is used on some localĪrea networks), multicast clients receive a stream of packets Supports only the unicast mode, multicast applications must use Which denotes a specific multicast group. Of IP multicast packets is identical to that of unicast packetsĪnd is distinguished only by the use of a special class of destination Set of senders (at least 1) and a group of receivers. Multicast provides dynamic many-to-many connectivity between a ![]() Same packet simultaneously to a group of clients. ![]() Multicasting is the networking technique of delivering the Way to significantly ease scaling to larger groups of clients This poses a major salability issueįor applications which required sustained high bandwidth. Will exhaust the capability of even a high bandwidth network withĪ powerful video clip server. Of high quality video to each of a large number of delivery platforms Video server sending out networked TV channels. One example of an application which may use multicast is a May be no receivers, or any other number of receivers). In this case there is may be one or more senders,Īnd the information is distributed to a set of receivers (theer Multicast is the term used to describe communication whereĪ piece of information is sent from one or more points to a set Network layer protocols (such as IPv4) also support a form of broadcast that allows the same packet to be sent to every system in a logical network (in IPv4 this consists of the IP network ID and an all 1's host number). the address resolution protocol (arp) uses this to send an address resolution query to all computers on a LAN, and this is used to communicate with an IPv4 DHC server). Send the same message to all computers on the LAN (e.g. In this case there is just one sender, but the information isīroadcast transmission is supported on most LANs (e.g. Smtp, ftp and telnet) which employ the TCPīroadcast is the term used to describe communication whereĪ piece of information is sent from one point to all other points. Networks support the unicast transfer mode, and most usersĪre familiar with the standard unicast applications (e.g. Of transmission on LANs and within the Internet. Source to a specified destination, is still the predominant form Unicast transmission, in which a packet is sent from a single In this case there is just one sender, and one receiver. Piece of information is sent from one point to another point. Unicast is the term used to describe communication where a Unicast, Broadcast, and Multicast Unicast
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