Cloud computing and the Big Data Era Network technology Revelation (17) Voq mechanism

VOQ mechanism

The VOQ described in this chapter is a new QoS mechanism designed to solve the famous switch hol problem.

However, VOQ relies heavily on scheduling algorithms, such as a 48-port switch, which maintains 48-1 FIFO cache queues each.

A total of 48x47=2256 cache queue, on the one hand, the hardware conditions of the switch have raised high requirements, but also how to design a good

Forwarding packet scheduling algorithm presents a huge challenge, and at present only the Cisco family has launched a commercial product, which is a demonstration of its complexity.

Learning how to solve the problem of the VOQ solution, or help us to better understand the internal operation of the switch mechanism.

Figure Hol The origin of the problem

This process is simply described as:

Inbound ports 1, 3 have a packet destined for Port 4

Assuming that data on port 1 is EF-level (QoS), 3-port data is AF-level

Since the switch can handle only one forwarding operation in a time series, 1 port data is sent to 4

Subsequent processing of 1-port packets due to QoS priority levels

Subsequent packets on port 3 cannot be forwarded due to packet blocking on the queue header

This is the head-end blocking problem for the switch.

Cloud computing and the Big Data Era Network technology Revelation (17) Voq mechanism