Quality of Service

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Defining Queues

 

 

 

 

 

Queue Configuration Recommendations

It is recommended that higher numbered queues be configured with higher priority, weight, and minimum-bandwidth settings.

The following are recommended scenarios for strict priority (SP) and WRR queues:

All eight queues in SP mode (q8 > q7 > q6 > q5 > q4 > q3 > q2 > q1). q8 is allocated bandwidth as long as there are packets to serve in q8. Then Q7 is served, followed by Q6, and so forth.

All 8-queues in WRR mode (q8:q7:q6:q5:q4:q3:q2:q1 = A:B:C:D:E:F:G:H). In this mode, each queue is allocated its minimum bandwidth according to the weights configured.

One queue in SP mode and all other queues in WRR mode (q8 > q7/q6/.../ q1 and q7::q1 = A::G). In this scenario q8 is configured in SP mode and q7 through q1 in WRR mode.

Four queues in SP mode and four queues in WRR mode (q8 > q7 > q6 > q5 > q4/q3/q2/q1 and q4/q3/q2/q1 = A:B:C:D): In this scenario q8, q7, q6, and q5 are configured in strict mode with q4, q3, q2 and q1 in WRR mode.

When there are more ingress ports with traffic destined to different queues on egress ports, a system might encounter a Head of Line Blocking (HOL) condition. HOL could result in higher numbered queues getting more bandwidth, although higher numbered queues are configured with lower bandwidth and weight. It is always recommended that higher numbered queues with higher weight be configured in SP mode, so that even in a HOL condition, the desired egress segregation is achieved.

Configuring Queues

To configure QoS properties:

STEP 1 Click Quality of Service > Queue in the navigation window.

STEP 2 Select from the Interface drop-down menus the Port or the LAG to configure.

STEP 3 Select one of the following modes for each queue on the selected interface:

Strict Priority—Select to have the scheduler forward traffic strictly based on the priority levels in the queues. The queue with the highest priority traffic has access to the egress port until all such traffic is forwarded. Strict priority mode provides low-latency service to higher priority classes of traffic.

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Cisco Systems SLM2008PTNA manual Queue Configuration Recommendations, Configuring Queues

SLM2008PTNA specifications

Cisco Systems SLM2008PTNA is a robust network switch designed specifically for small to medium-sized businesses. It operates with 8 Fast Ethernet ports, providing advanced features and best-in-class performance to enhance your network infrastructure. This model ensures seamless connectivity for multiple devices, making it an ideal choice for environments requiring reliable network communication.

One of the standout features of the SLM2008PTNA is its Layer 2 switching capabilities. This switch supports auto-negotiation, which allows each port to automatically detect the speed of the connected device and adjust accordingly. This ensures optimal performance and smooth operation across various connected devices. Additionally, the switch supports a non-blocking architecture, ensuring that bandwidth is not shared, which significantly enhances data transmission speed.

Power over Ethernet (PoE) is another key technology incorporated into the Cisco SLM2008PTNA. It simplifies the installation of network devices such as VoIP phones, security cameras, and wireless access points by supplying power through the Ethernet cable. This eliminates the need for separate power sources, reducing installation costs and increasing flexibility in device placement.

Moreover, the SLM2008PTNA comes equipped with advanced security features, such as port security and VLAN support. Port security allows network administrators to restrict access to the network based on MAC addresses, preventing unauthorized access and enhancing network security. The support for Virtual Local Area Networks (VLANs) enables the segmentation of the network into different logical networks, improving traffic management and security within each segment.

The switch is designed for easy management and monitoring, featuring a user-friendly web interface that simplifies configuration. This allows network administrators to quickly set up and manage the device without requiring extensive technical knowledge. Additionally, its compact design makes it suitable for desktop or rack-mount installation, maximizing space efficiency in network environments.

In conclusion, the Cisco Systems SLM2008PTNA is an essential component for small to medium-sized businesses looking to enhance their network performance. With its Layer 2 switching capabilities, Power over Ethernet support, advanced security features, and ease of management, this switch provides a well-rounded solution for modern networking needs, delivering reliable performance and scalability for growth.