A brilliant feature, voice VLAN allows access ports to handle IP phone voice traffic. Cisco IP phones are able to transmit VoIP packets via an Ethernet connection to an IP network. IP phones, call managers, and voice gateways are the building blocks of the Voice over IP architecture.
In today’s businesses, it’s not uncommon for each workstation to have a personal computer and an IP phone. An alternative method of linking the IP phone to the switch could have involved using an individual Ethernet cable and port on the switch. However, Cisco devised the notion of embedding a miniature LAN switch into every Cisco IP phone. One Cable runs from the LAN switch on the other end of the desk to the IP phone’s internal switch. Subsequently, a brief, straight-through Ethernet connection can be established between the computer and the IP phone’s internal switch. In the event that you happen to possess a Cisco IP Phone, inverting it will reveal two Ethernet ports located at the base. The LAN switch should be linked to one port, the PC to another, and the IP phone circuitry within to the third internal port. All Cisco IP phones come equipped with this basic three-port switch. Thus, in addition to transmitting voice data, a Cisco IP phone can also link to a user’s personal computer. A graphical illustration of the topic just discussed can be found in the figure below.
The link between the phone and the switch must to be built with 802.1Q trunking, as can be seen in the diagram. Additionally, the phone and the personal computer ought to be in different VLANs, and consequently, in different IP subnets. This design is in accordance with the guidelines set by Cisco and offers a number of benefits. To begin, you can more easily manage the IP address space, implement Quality of Service (QoS), and provide greater security by segregating the data and voice traffic by placing IP phones in one VLAN and the personal computers that are connected to the phones in a different VLAN.
A switch can usually forward frames as soon as they are received on a network that is quiet or is in less utilized networks. Though, if a network is busy, packets might not always get delivered on time. There are different ways that data needs to be sent from one end to the other for different types of applications. For instance, it might be okay to wait a short time for a Web page to load after a user has asked for it. Also, an FTP download can go on at different speeds without any problems because the user can use the file once it’s fully downloaded. But probably not being able to stand having to wait the same amount of time to receive packets for a phone call or a streaming video. Most of the time, multicast traffic over UDP is used to send the video stream from a server to multiple clients. Video streaming is very popular these days. Because these voice & video applications work in real time so any loss or delay in packet transfer would make them useless.
