¾Multicast Address

1. Multicast IP Address:

As specified by IANA (Internet Assigned Numbers Authority), Class D IP addresses are used as destination addresses of multicast packets. The multicast IP addresses range from 224.0.0.0~239.255.255.255. The following table displays the range and description of several special multicast IP addresses.

Multicast IP address range

Description

 

 

224.0.0.0224.0.0.255

Reserved multicast addresses for routing protocols

 

and other network protocols

 

 

224.0.1.0224.0.1.255

Addresses for video conferencing

 

 

239.0.0.0239.255.255.255

Local management multicast addresses, which are

 

used in the local network only

 

 

Table 8-1 Range of the special multicast IP

2. Multicast MAC Address:

When a unicast packet is transmitted in an Ethernet network, the destination MAC address is the MAC address of the receiver. When a multicast packet is transmitted in an Ethernet network, the destination is not a receiver but a group with uncertain number of members, so a multicast MAC address, a logical MAC address, is needed to be used as the destination address.

As stipulated by IANA, the high-order 24 bits of a multicast MAC address begins with 01-00-5E while the low-order 23 bits of a multicast MAC address are the low-order 23 bits of the multicast IP address. The mapping relationship is described as Figure 8-2.

Figure 8-2 Mapping relationship between multicast IP address and multicast MAC address

The high-order 4 bits of the IP multicast address are 1110, identifying the multicast group. Only 23 bits of the remaining low-order 28 bits are mapped to a multicast MAC address. In that way, 5 bits of the IP multicast address is not utilized. As a result, 32 IP multicast addresses are mapped to the same MAC addresses.

¾Multicast Address Table

The switch is forwarding multicast packets based on the multicast address table. As the transmission of multicast packets cannot span the VLAN, the first part of the multicast address table is VLAN ID, based on which the received multicast packets are forwarded in the VLAN owning the receiving port. The multicast address table is not mapped to an egress port but a group port list. When forwarding a multicast packet, the switch looks up the multicast address table based on the destination multicast address of the multicast packet. If the corresponding entry can not be found in the table, the switch will broadcast the packet in the VLAN owning the receiving port. If the corresponding entry can be found in the table, it indicates that the destination address should be a group port list, so the switch will duplicate this multicast data and deliver each port one copy. The general format of the multicast address table is described as Figure 8-3below.

VLAN ID

Multicast IP

Port

Figure 8-3 Multicast Address Table

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TP-Link TL-SG3424P manual ¾ Multicast Address Table, Multicast IP Port

TL-SG3424P specifications

The TP-Link TL-SG3424P is a high-performance managed switch designed to meet the needs of small to medium-sized businesses. Offering 24 Gigabit Ethernet ports, this device is an ideal solution for improving network efficiency and ensuring seamless data transfer across multiple devices. The switch not only facilitates connectivity but also provides robust management features to enhance the performance and security of your network.

One of the standout features of the TL-SG3424P is its Power over Ethernet (PoE) capability, which allows it to deliver power and data over the same Ethernet cable. This feature is particularly beneficial for deploying devices such as IP cameras, VoIP phones, and wireless access points without the need for additional power sources. With a total power budget of 250W, the TL-SG3424P can support a diverse range of PoE devices, providing convenience and flexibility in deployment.

In terms of management, the TL-SG3424P offers a user-friendly web interface, allowing network administrators to configure and monitor the switch with ease. It supports advanced Layer 2 features, including VLANs, Quality of Service (QoS), and Link Aggregation. These features enhance network performance by optimizing traffic flow and prioritizing essential applications. The switch also includes comprehensive security features, such as Port Security and Access Control Lists (ACL), which help protect against unauthorized access and ensure data integrity.

The build quality of the TL-SG3424P is robust, designed to handle demanding network environments. It includes a fanless design, which ensures silent operation, making it suitable for office environments where noise can be a distraction. The metal chassis is durable and built for longevity, ensuring that the device will withstand rigorous usage over time.

Furthermore, the TL-SG3424P supports SNMP (Simple Network Management Protocol), allowing for centralized network monitoring and management. This makes it easier for IT teams to keep track of network health and performance, enabling timely interventions when necessary.

In conclusion, the TP-Link TL-SG3424P is a versatile and powerful managed switch that combines PoE capabilities with advanced network management features, making it a perfect choice for businesses looking to upgrade their network infrastructure. With its reliable performance and robust features, it provides an excellent solution for enhancing productivity and connectivity in any office setting.