BLADEOS 6.5.2 Application Guide

Priority-Based Flow Control

Priority-based Flow Control (PFC) is defined in IEEE 802.1Qbb. PFC extends the IEEE 802.3x standard flow control mechanism. Under standard flow control, when a port becomes busy, the switch manages congestion by pausing all the traffic on the port, regardless of the traffic type. PFC provides more granular flow control, allowing the switch to pause specified types of traffic on the port, while other traffic on the port continues.

PFC pauses traffic based on 802.1p priority values in the VLAN tag. The administrator can assign different priority values to different types of traffic and then enable PFC for up to two specific priority values: priority value 3, and one other. The configuration can be applied globally for all ports on the switch. Then, when traffic congestion occurs on a port (caused when ingress traffic exceeds internal buffer thresholds), only traffic with priority values where PFC is enabled is paused. Traffic with priority values where PFC is disabled proceeds without interruption but may be subject to loss if port ingress buffers become full.

Although PFC is useful for a variety of applications, it is required for FCoE implementation where storage (SAN) and networking (LAN) traffic are converged on the same Ethernet links. Typical LAN traffic tolerates Ethernet packet loss that can occur from congestion or other factors, but SAN traffic must be lossless and requires flow control.

For FCoE, standard flow control would pause both SAN and LAN traffic during congestion. While this approach would limit SAN traffic loss, it could degrade the performance of some LAN applications that expect to handle congestion by dropping traffic. PFC resolves these FCoE flow control issues. Different types of SAN and LAN traffic can be assigned different IEEE 802.1p priority values. PFC can then be enabled for priority values that represent SAN and LAN traffic that must be paused during congestion, and disabled for priority values that represent LAN traffic that is more loss-tolerant.

PFC requires CEE to be turned on (“Turning CEE On or Off” on page 192). When CEE is turned on, PFC is enabled on priority value 3 by default. Optionally, the administrator can also enable PFC on one other priority value, providing lossless handling for another traffic type, such as for a business-critical LAN application.

Note – For any given port, only one flow control method can be implemented at any given time: either PFC or standard IEEE 802.3x flow control.

200 ￿ Chapter 14: FCoE and CEE

BMD00220, October 2010

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Blade ICE G8124-E manual Priority-Based Flow Control
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G8124-E, G8124 specifications

The Blade ICE G8124 is a cutting-edge networking solution designed for high-performance data center environments. It has emerged as a popular choice among organizations that require reliable and efficient network infrastructure to support their growing demands for bandwidth and low-latency connectivity.

One of the key features of the Blade ICE G8124 is its high port density. This networking device typically offers 24 ports of 10 Gigabit Ethernet, ensuring that businesses can connect numerous devices without requiring extensive physical space. The design is also scalable, accommodating future expansion as organizational needs grow.

Another significant aspect of the G8124 is its advanced switching capabilities. It utilizes a non-blocking architecture, enabling simultaneous data transmissions on all ports. This characteristic ensures that there is no bottleneck in the network traffic, providing the high performance needed in data-intensive applications.

The G8124 incorporates various technologies to enhance its functionalities. It supports Layer 2 and Layer 3 switching, making it versatile for different networking needs. Additionally, it features comprehensive Quality of Service (QoS) settings that prioritize critical applications, such as VoIP and video streaming, ensuring smooth operation even under heavy loads.

In terms of security, the Blade ICE G8124 provides robust measures to protect the network. It supports features such as Access Control Lists (ACLs), port security, and VLANs, allowing administrators to segment the network and restrict unauthorized access. These security capabilities are vital in today’s landscape, where cyber threats are increasingly common.

Moreover, the G8124 offers excellent management features. It includes an intuitive user interface for easy configuration and monitoring of network performance. SNMP support allows integration with network management systems, providing administrators with insights needed to optimize their operations.

Power efficiency is also a hallmark of the Blade ICE G8124. It employs energy-saving technologies that reduce operational costs, an essential factor for environmentally-conscious organizations striving to minimize their carbon footprint.

In summary, the Blade ICE G8124 stands out with its high port density, advanced switching capabilities, robust security features, and efficient management options. This networking solution is designed to meet the demands of modern data centers, providing the performance, reliability, and scalability that organizations require. With its innovative technologies, the G8124 ensures that businesses can navigate the complexities of today's networking landscape effectively.
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