Per-VLAN Spanning Tree Groups

BLADEOS 6.5.2 Application Guide

STP/PVST+ mode supports a maximum of 127 STGs, with each STG acting as an independent, simultaneous instance of STP.

Multiple STGs provide multiple data paths which can be used for load-balancing and redundancy. To enable load balancing between two G8124s using multiple STGs, configure each path with a different VLAN and then assign each VLAN to a separate STG. Since each STG is independent, they each send their own IEEE 802.1Q tagged Bridge Protocol Data Units (BPDUs).

Each STG behaves as a bridge group and forms a loop-free topology. The default STG 1 automatically contains any newly configured VLANs until they can be assigned to another STG. STGs 2-128 may contain only one VLAN each.

Using Multiple STGs to Eliminate False Loops

Figure 11 shows a simple example of why multiple STGs are needed. In the figure, two ports on a G8124 are connected to two ports on an application switch. Each of the links is configured for a different VLAN, preventing a network loop. However, in the first network, since a single instance of Spanning Tree is running on all the ports of the G8124, a physical loop is assumed to exist, and one of the VLANs is blocked, impacting connectivity even though no actual loop exists.

Figure 11 Using Multiple Instances of Spanning Tree Group

BLADE Switch


1			30
VLAN	False	x	VLAN
	Loop

BLADE Switch


STG 1				STG 2
VLAN 1				VLAN 30
is active				is active

Application Switch	Application Switch
With a single Spanning Tree,	Using multiple STGs,
one link becomes blocked.	Both links may be active.

In the second network, the problem of improper link blocking is resolved when the VLANs are placed into different Spanning Tree Groups (STGs). Since each STG has its own independent instance of Spanning Tree, each STG is responsible only for the loops within its own VLAN. This eliminates the false loop, and allows both VLANs to forward packets between the switches at the same time.

BMD00220, October 2010

Chapter 8: Spanning Tree Protocols 117

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.

Blade ICE G8124-E Per-VLAN Spanning Tree Groups, Using Multiple Instances of Spanning Tree Group

Models: G8124-E G8124

BLADEOS 6.5.2 Application Guide