Multicasting

Multicasting: Issues and Networking Support

UPKAR VARSHNEY , in Multimedia Communications, 2001

16.8 SUMMARY AND THE FUTURE OF MULTICASTING

Multicasting is required past several multimedia applications and therefore information technology is of pregnant importance. There has been some progress in support for multicasting in IP, ATM, and wireless networks. The factors affecting the widespread deployment of multicast communications include the maturity of multicast software; congestion control and reliable multicast support; support for multicasting by vendors; involvement in multicasting by CLEC, Internet service provider, and content providers, evolution of new econometric models for division of revenue among multiple networks or ISPs; ways to charge and measure the use of multicasting; and the amount of traffic actually caused by multicast communications on corporate networks or the Internet.

Read full chapter

URL:

https://www.sciencedirect.com/science/commodity/pii/B9780122821608500177

Understanding Networks and Networked Video

Anthony C. Caputo , in Digital Video Surveillance and Security (Second Edition), 2014

Multicast

Multicasting is divers as a single source sending to multiple recipients on a network when the receiver broadcasts a signal for acceptance. Multicasting has its ain Class D IP addressing scheme, controlled and assigned by the Cyberspace Assigned Numbers Authority (IANA). This means that all IP multicasts are in the range of 224.0.0.0 to 239.255.255.255. This unique IP address range is used only for the destination address of IP multicast traffic; the server, encoder, or IP photographic camera delivering the multicast datagrams is always the unicast source IP accost.

Multicasting dramatically reduces network traffic by delivering a single video stream to multiple receivers (come across Effigy iv.xi). For example, by using unicasting in a DVS organization with redundancy archivers, there is a video stream per backup archiver plus (depending on the VMS used) a unmarried video stream per client station. Thus, with three backup archive servers and three client stations, one camera will send six dissimilar streams. Multicasting, on the other mitt, was created for sound and video transmission over IP networks, allowing a single video stream to be delivered to multiple recipients. Multicasting is besides a i-way connexion, and then it cannot be transported via TCP, which requires confirmation of connectivity. Multicasting, by its very nature, is but sent via UDP (so make sure those UDP ports are open up).

Effigy 4.11. Multicasting uses a single stream for each host.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780124200425000046

Multimedia Networks and Advice

Shashank Khanvilkar , ... Ashfaq Khokhar , in The Electrical Technology Handbook, 2005

Multicasting Support

Multicasting refers to a unmarried source of communication with simultaneous multiple receivers. Near popular distributed multimedia applications require multicasting. For case, multiparty audio/video conferencing is one of the most widely used services in Net telephony. If multicasting is not naturally supported by the communication network (as was the case in some excursion-switched networks) then significant efforts need to exist invested in edifice multimedia applications that back up this functionality in an overlaid fashion, which often leads to inefficient bandwidth utilization.

Multicasting is relatively easier to reach for one-mode advice than for two-way communication. For example, in the example of Internet radio, multicasting can be accomplished by creating a spanning tree consisting of the sender at the root and the receiver at the leaves too as replicating packets over all links that reach the receivers. In the case of two-way communication similar Internet telephony amid multiple parties, nonetheless, some course of audio mixing functionality is required that mixes the audios from all participants and simply relays the correct information. Without this audio mixer, a 2-manner communication channel needs to be established between each participant in an all-to-all mesh fashion, which may amount to waste of bandwidth.

Read total chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780121709600500335

IGPs

Walter Goralski , in The Illustrated Network (Second Edition), 2017

Multicasting

Multicasting is a kind of "halfway" distribution method between unicast (one source to ane destination) and broadcast (ane source to all possible destinations). Unlike broadcasts that are received by all nodes on the subnet, simply devices that join the RIPv2 multicast group will receive packets for RIPv2. (We'll talk more about multicast in Chapter 16.) RIPv2 multicasting also offers a way to filter out RIPv2 messages from a RIPv1 only router. This can be important, since RIPv2 messages expect very much like RIPv1 messages. But RIPv2 messages are all invalid past RIPv1 standards. RIPv1 devices would either discard RIPv2 messages considering the mandatory all-cipher fields are not all zeroes, or accept the routes and ignore the additional RIPv2 information such as the subnet mask. RIPv2 multicasting makes sure that merely RIPv2 devices see the RIPv2 information. So RIPv1 and RIPv2 routers can easily coexist on the same LAN, for instance. The multicast grouping used for RIPv2 routers is 224.0.0.nine.

RIPv2 is still express in several means. The 15 maximum-hop count is still at that place, as well every bit counting to infinity to resolve routing loops. And RIPv2 does nothing to improve on the fixed distance-vector values that are a feature of all versions of RIP.

Read full affiliate

URL:

https://www.sciencedirect.com/scientific discipline/article/pii/B9780128110270000151

Networking

Colin Walls , in Embedded Software (Second Edition), 2012

8.10.1 Initializing Multicasting

IP multicasting provides a means for a network application to send a single IP datagram to multiple hosts. Multicasting differs from broadcasting in that every host on a network segment receives a broadcast packet. This can lead to unnecessary interruptions for those hosts that are non interested in the broadcast. With multicasting, just those hosts that have explicitly joined an IP multicasting group will receive a multicast packet to that accost/grouping. The course D IP address space defines the multicasting IP addresses. These addresses practice not define private interfaces, only instead define groups of interfaces. Hence class D addresses are referred to as groups. The grade D IP addresses are those in the range 224.0.0.0 to 239.255.255.255.

Membership in a multicast group is dynamic. An application can join and leave a group on an interface at any time. Applications join or leave a multicast grouping by utilizing a networking stack service call. Many IP multicasting groups are reserved for specific applications. RFC 1700 provides a electric current list of registered groups.

All level 2 conforming hosts are required to bring together the 224.0.0.1 group at initialization. The 224.0.0.1 or "all hosts group" is the group of all hosts on the local subnet. At initialization, a networking stack, which supports IP multicasting, will join this grouping on interfaces that back up multicasting (this would normally exist a build selection). Multicasting can only exist enabled on UDP sockets. This is because UDP is a connectionless protocol. TCP on the other mitt establishes a connection with a specific host. Advice over a TCP socket is possible only with that one specific host.

IGMP (Internet Group Management Protocol) is the means by which IP hosts report their host group memberships to any immediately neighboring multicast routers. A networking stack may besides have back up for IGMP. IGMP is transparent to the user in that no API service calls straight invoke IGMP. Rather, each time an application joins a multicast group, the IGMP services will be invoked by the IP layer to report the new group membership. Also, if there are whatsoever multicast routers on the local network, they will periodically ship requests for updated group membership information. At this time, IGMP will report all group memberships to the router. These requests are sent past routers to the group accost of 224.0.0.1, hence the necessity of joining this grouping during boot upwards on all interfaces that support multicasting.

It is important to go along definitions straight. In this article, references to multicast packets volition mean packets that contain application data and are sent to a multicast grouping address. IGMP packets refer to packets that contain instructions for multicast group maintenance.

Read full chapter

URL:

https://www.sciencedirect.com/scientific discipline/commodity/pii/B9780124158221000088

Using social network analysis (SNA) to design socially aware network solutions in delay-tolerant networks (DTNs)☆

B. Jedari , ... Y. Najaflou , in Advances in Delay-Tolerant Networks (DTNs) (Second Edition), 2021

12.iv.3 Social-based multicasting

Multicasting is an effective method for efficient data dissemination and multiparty communication in DTNs. For example, in sparse vehicular ad hoc networks, a vehicle may disseminate live traffic information to other following vehicles ( Pereira et al., 2012). According to Ye et al. (2009), some problems tin can arise if Internet-based multicast routing methods are practical in DTNs. First, it is difficult to maintain the connectivity of a multicast structure during the lifetime of a multicast session. Second, data transmissions would suffer from many failures and large terminate-to-finish delays because of the disruptions caused past repeatedly broken multicast branches. Third, the traditional approaches are designed with the assumption that the underlying networks are basically connected.

The state-of-the-art multicasting protocols for DTNs have utilized community and axis concepts to improve multicasting operation. For instance, the social network-aided multicast delivery (Chuah, 2009) scheme made use of the community concept to evangelize multicast messages efficiently. The scheme is motivated by the following observations: a node should forwards a copy to an encountered node if that encountered node either is in the aforementioned customs equally any of the destination nodes or has a higher risk of reaching whatsoever of the destination nodes. Quite recently, a probabilistic socially aware multicast (Gao et al., 2012) was proposed which uses two key concepts, centrality, and communities, to improve the cost-effectiveness of multicast. In this piece of work, the authors advise a community-based approach that only requires nodes to maintain the probabilities of forwarding each data item to other nodes in the same community. When the destinations are in other communities, data forwarding is conducted through some gateway nodes which belong to multiple communities. However, this model increases computational complexity considerably.

Read full chapter

URL:

https://www.sciencedirect.com/scientific discipline/article/pii/B9780081027936000126

Multimode Communications Using Orbital Athwart Momentum

Jian Wang , ... Alan E. Willner , in Optical Cobweb Telecommunication (Sixth Edition), 2013

12.6.3 Multicasting

A multicasting function (i.eastward. fanout) indicates that information on a single aqueduct tin exist duplicated onto multiple channels, without the need of detection and remodulation processes. Previously, wavelength and time slots channels have been multicasted in order to replicate the data such that they co-propagate and can be dissever subsequently for dissimilar potential user destinations [79,80]. Following the same concept, it might be desirable to multicast data data from one OAM aqueduct to multiple different OAM channels [81].

The multicasting function can be achieved through a programmable SLM, as shown in Figure 12.31a. The multiple OAM beams afterward multicasting tin can exist either divergent or collimated, adamant past the phase blueprint used for the SLM.

Figure 12.31. (a) Concept of data channel multicasting in an OAM-based mode-division multiplexing system. A spatial light modulator is used to distribute energy from a single input OAM channel to multiple OAM channels. (b) Principle of "divergent" OAM aqueduct multicasting. (c) Concept and principle of "collimated" OAM aqueduct multicasting (MC). (left: the designed phase pattern for multicasting, right: concept diagram). (d) Simulated and experimental results: power distribution on each OAM aqueduct before and after multicasting.

To achieve a divergent multicasting, a fork pattern (superposition of a spiral stage profile and a blazed grating) can be loaded to the SLM. Due to the diffraction of the grating, the beam can exist split into multiple diffraction orders, each with a unlike reflecting angle in the incident plane, and therefore with different OAM orders. For case, if the incoming OAM beam has an order of l, and the fork pattern includes a spiral phase pattern in the order of 1000, then the OAM orders afterward multicasting become l+nk (northward  =   0, ±1, ±2, ±three, … is the diffraction lodge). The divergent bending of each beam is adamant past the blazed grating period. Moreover, past combing two "fork" stage patterns with 1 perpendicular to the other, we can attain multicasting at both ten-axis and y-centrality directions, as shown in Figure 12.31b.

In some cases, the multicasted copies of a data channel need to exist multiplexed (i.e. overlapped in the spatial domain). The approach for the "collimated" multicasting is shown in Figure 12.31c. A information stream carried by one OAM beam can be easily duplicated and loaded onto different OAM charges/beams by using a phase-only SLM with a especially designed stage mask. As an example, Figure 12.31c shows the phase pattern to multicast the input OAM beam (OAM+15) to five channels (OAM+6, OAM+ix, OAM+12, OAM+15, and OAM+18). After multicasting, the input OAM way becomes the superposition of multiple OAM modes having a triangle intensity distribution. Figure 12.31d shows the ability distribution before and subsequently multicasting. The crosstalk between the three equalized spatial channels of l   =   9, 12, and fifteen and undesired spatial channels is beneath −20   dB.

Read full chapter

URL:

https://world wide web.sciencedirect.com/scientific discipline/article/pii/B9780123969606000122

Multicast

Walter Goralski , in The Illustrated Network (2d Edition), 2017

Frames and Multicast

Multicasting on a LAN is a good place to start an investigation of multicasting in full general. Consider a single LAN, without routers, with a multicast source sending to a sure group. The remainder of the hosts are receivers interested in the multicast group'south content. So, the multicast source host generates packets with its unicast IP address every bit the source and the group address as the destination.

Ane issue comes up immediately. The packet source accost obviously will be the unicast IP address of the host originating the multicast content. This translates to the MAC accost for the source address in the frame in which the packet is encapsulated. The packet's destination address will be the multicast group. So far, so adept. But what should exist the frame'due south destination address that corresponds to the bundle's multicast group accost?

Using the LAN broadcast MAC address defeats the purpose of multicast, and hosts could have access to many multicast groups. Broadcasting at the LAN level makes no sense. Fortunately, there is an easy style out of this. The MAC address has a bit that is set to 0 for unicast (the LAN term is private accost) and to a 1 to indicate that this is a multicast address. Some of these addresses are reserved for multicast groups for specific vendors or MAC-level protocols. Net multicast applications use the range 0x01-00-5E-00-00-00 to 0x01-00-5E-FF-FF-FF. TCP/IP multicast receivers mind for frames with one of these addresses when the application joins a multicast group and stops listening when the awarding terminates or the host leaves the grouping.

So, 24 $.25 are available to map IPv4 multicast addresses to MAC multicast addresses. Only all IPv4 addresses, including multicast addresses, are 32 bits long. There are viii bits left over. How should IPv4 multicast addresses exist mapped to MAC multicast addresses to minimize the run a risk of "collisions" (two different multicast groups mapped to the aforementioned MAC multicast address)?

All IPv4 multicast addresses begin with the same four bits (1110), then nosotros merely have to really worry about 4 bits (non 8). We shouldn't driblet the final bits of the IPv4 address, considering these are well-nigh guaranteed to be host bits—depending on subnet mask. Merely the high-club $.25, the rightmost $.25, are almost e'er network $.25 and we're merely worried about one LAN for now.

1 other fleck of the remaining 24 MAC address $.25 is reserved (an initial 0 indicates an Internet multicast address), so allow'southward merely driblet the 5 bits following the initial 1110 in the IPv4 accost and map the 23 remaining bits (one for i) into the last 23 bits of the MAC accost. This procedure is shown in Figure 18.5.

Figure 18.5. How to convert from IPv4 header multicast to Ethernet MAC multicast accost formats.

Notation that this process ways that there are 32 (25) IPv4 multicast addresses that could map to the aforementioned MAC multicast addresses. For example, multicast IPv4 addresses 224.8.7.6 and 229.136.vii.6 translate to the same MAC address (0x01-00-5E-08-07-06). This is a real concern, and because the host will have frames sent to both multicast groups, the IP software must reject one or the other. This problem does not exist in IPv6, only is always a concern in IPv4.

Once the MAC address for the multicast group is determined, the operating system essentially orders the NIC bill of fare to join or leave the multicast group and accept frames sent to the address too equally the host'south unicast address or ignore that multicast group's frames. It is possible for a host to receive multicast content from more than one grouping at the same time, of course. The process for IPv6 multicast packets within frames is nearly identical, except for the MAC destination address 0x3333 prefix and other points outlined in the previous department.

Read full chapter

URL:

https://www.sciencedirect.com/scientific discipline/commodity/pii/B9780128110270000187

TCP/IP and Routing

Naomi J. Alpern , Robert J. Shimonski , in Eleventh Hour Network+, 2010

Multicast, Broadcast, and Unicast

■

Multicasting tin can exist used to push data to multiple hosts simultaneously. Characteristics of multicasting are equally follows:

■

Designed to handle traffic destined to multiple hosts.

■

Multicast traffic establishes a one-to-many type of transmission, sending ane stream of traffic to each requesting circulate domain.

■

The IP address that defines a multicast group is a Form D address (224.0.0.0 to 239.255.255.255).

■

Multicast addresses cannot be used every bit source addresses for any traffic.

■

A multicast accost identifies a group of hosts sharing the same address.

■

Multicast addresses are not assigned to a device, rather, a device proceeds to listen for and receive traffic destined to a multicast group that it has joined by some procedure.

■

Multicasting is UDP-based.

■

A computer uses Net Group Management Protocol (IGMP) to report its multicast group memberships to multicast routers.

■

IGMP is required to be used in host computers that wish to participate in multicasting.

■

Unicast traffic is the manual of data from one host to another, one host at a time. Characteristics of unicast traffic are equally follows:

■

A one-to-i session betwixt 1 host and another, such as a client and server arrangement.

■

It will not transmit to every computer on a network.

■

Multiple requests for the aforementioned conference or data would cause that data to be pushed beyond the network media at the same fourth dimension to multiple targets. An example of this is shown in Figure half dozen.two.

■

Circulate traffic is the broadcast traffic sent to all estimator systems that tin exist reached on the network. Characteristics of circulate traffic are as follows:

■

Each host receiving the broadcast has to process the broadcast traffic.

■

If a host does not require the circulate traffic data, the host will nonetheless accept the datagram and then determine what to do with it – accept it or reject it.

■

Routers filter (block) circulate traffic by default. Broadcasts must be explicitly immune to traverse routers.

FIGURE 6.2. Unicast network video feed example

Read total chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9781597494281000011