11. VoIP network problem

1. Delay/lantency

• Defined as number of times it takes for speech to transmit from the sender to the receiver.
• There are 3 types of delay:Propogation delay, serialization delay and handling delay.
• Propagation delay is caused by spped of light in fiber or copper based network.
• Handlinh delay defines many different causes if dalay(actual packetization, compression and packet switching). It is usually caused by devices that forward frames through network.
• Sertization delay is the amount of time that it takes to place sa bit or byte onto an interface. It's influence to delay is relatively minimal.
• Delay can be controlled by assigning a higher priority for voice packets in VoIP.

2. Jitter

• Define as the variation of packets interarrival time.
• one of the issuse that exits only in packet basred network.
• In a VoIP environment, sender send voice packets at a regular interval( For e.g., sender send voice packet about 20ms).
• In order to send it in order, these packets can be delay and transmit them at the receiving end.
• Jitter can also be know as the differences between the packet expected to and when it actually received.

3. Packet loss

• It is the most common in data network.
• It has a direct result of the quencing scheme used in routers.
• The solution in reducing packet loss is to implement priority queuing, weighed fair queuing, or class-based wieghted fair queuing,whereby traffic amount are assigned to differrent to classes of data traffic.
• But, many protocols used packet loss to reduced number of packets they are sending.
• In VoIP, it is implement to control amount of packet loss in the network.