What Are the Changes of New Cisco CCIE EI?

FIFO (First Input First Output), that is, first in, first out queue. FIFO is the simplest queue mechanism. There are FIFO queues on each interface. FIFO is the basis of other queues, and FIFO will also affect the discarding, delay and jitter of key indicators of QOS. Since there is only one queue, there is naturally no need to consider how to classify the complex traffic of messages, nor how to get and how many messages to get next. Moreover, because the messages are retrieved in order, FIFO does not need to reorder the messages. Simplifying these implementations improves the guarantee of packet delay.

FIFO concerns the queue length, affecting the delay, jitter and packet loss rate. Because the queue length is limited, it may be filled, which involves the discard principle of the mechanism. A common discard principle is called Tail Drop Mechanism.

In short, if the queue is complete, the subsequent incoming messages will be discarded, and there is no mechanism to ensure that the subsequent messages can squeeze out the messages already in the queue. In this mechanism, if a long queue length is defined, the queue is not easy to fill, and the number of discarded messages is less.

However, if the queue length is too long, the problem of delay will occur. Generally, the increase in delay will lead to an increase of jitter. If a shorter queue is defined, the delay problem can be solved, but there will be more messages with a tail drop.

FIFO Scheduling Mechanism for Congestion Management

FIFO (First Input, First Output) is the first in, first out queue. FIFO is the most straightforward queue mechanism. There are FIFO queues on each interface. FIFO is the basis of other queues, and FIFO will also affect the discarding, delay, and jitter of critical indicators of QOS.

Since there is only one queue, there is no need to consider how to classify the complex traffic of messages, nor how to get and how many messages to get next. Moreover, because the messages are retrieved in order, FIFO does not need to reorder the messages. Simplifying these implementations improves the guarantee of packet delay.

FIFO concerns the queue length, affecting the delay, jitter, and packet loss rate. Because the queue length is limited, it may be filled, which involves the discard principle of the mechanism. A common discard principle is called Tail Drop Mechanism.

In short, if the queue is full, the subsequent incoming messages will be discarded, and there is no mechanism to ensure that the subsequent messages can squeeze out the messages already in the queue. In this mechanism, if a long queue length is defined, the queue is not easy to fill, and the number of discarded messages is less.

However, if the queue length is too long, the problem of delay will occur. Generally, the increase in delay will lead to an increase in jitter. If a shorter queue is defined, the delay problem can be solved, but there will be more messages with a tail drop.