Chapter 13 Spanning Tree Protocol

Path cost is the cost of transmitting a frame onto a LAN through that port. The recommended cost is assigned according to the speed of the link to which a port is attached. The slower the media, the higher the cost.

Table 25 STP Path Costs

 

LINK

RECOMMENDED

RECOMMENDED

ALLOWED

 

SPEED

VALUE

RANGE

RANGE

Path Cost

4Mbps

250

100 to 1000

1 to 65535

 

 

 

 

 

Path Cost

10Mbps

100

50 to 600

1 to 65535

 

 

 

 

 

Path Cost

16Mbps

62

40 to 400

1 to 65535

 

 

 

 

 

Path Cost

100Mbps

19

10 to 60

1 to 65535

 

 

 

 

 

Path Cost

1Gbps

4

3 to 10

1 to 65535

 

 

 

 

 

Path Cost

10Gbps

2

1 to 5

1 to 65535

 

 

 

 

 

On each bridge, the root port is the port through which this bridge communicates with the root. It is the port on this switch with the lowest path cost to the root (the root path cost). If there is no root port, then this switch has been accepted as the root bridge of the spanning tree network.

For each LAN segment, a designated bridge is selected. This bridge has the lowest cost to the root among the bridges connected to the LAN.

13.1.2 How STP Works

After a bridge determines the lowest cost-spanning tree with STP, it enables the root port and the ports that are the designated ports for connected LANs, and disables all other ports that participate in STP. Network packets are therefore only forwarded between enabled ports, eliminating any possible network loops.

STP-aware switches exchange Bridge Protocol Data Units (BPDUs) periodically. When the bridged LAN topology changes, a new spanning tree is constructed.

Once a stable network topology has been established, all bridges listen for Hello BPDUs (Bridge Protocol Data Units) transmitted from the root bridge. If a bridge does not get a Hello BPDU after a predefined interval (Max Age), the bridge assumes that the link to the root bridge is down. This bridge then initiates negotiations with other bridges to reconfigure the network to re-establish a valid network topology.

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MGS3700-12C User’s Guide

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ZyXEL Communications metrogigabit switch How STP Works, 148, STP Path Costs, Link Recommended Allowed Speed Value Range
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metrogigabit switch specifications

ZyXEL Communications has long been a prominent player in the networking hardware industry, providing innovative solutions that cater to both business and consumer markets. Among their notable offerings is the Metrogigabit switch, a device designed to meet the high demands of modern networks.

The ZyXEL Metrogigabit switch is primarily aimed at service providers and large enterprises, recognizing the need for seamless connectivity in an increasingly digital world. This switch is engineered for scalability, enabling users to effortlessly expand their network as their operational needs grow. With support for high bandwidth, it is particularly suited for environments requiring extensive data traffic management, such as data centers and campus networks.

One of the standout features of the Metrogigabit switch is its high-density gigabit Ethernet ports, which provide a backbone for reliable data transmission. The switch typically supports multiple 10G SFP+ uplinks, ensuring fast and efficient connections to upstream devices. This capability allows users to configure their networks to handle large volumes of data quickly and without interruption.

In terms of technology, the Metrogigabit switch leverages advanced Layer 2 and Layer 3 functionalities. This includes features such as VLAN support for traffic segmentation, Quality of Service (QoS) for prioritizing mission-critical applications, and robust multicast management. These capabilities contribute to enhanced network efficiency and performance.

Another characteristic that sets the ZyXEL Metrogigabit switch apart is its built-in security features. The device is designed to protect network integrity through mechanisms like port security, access control lists, and advanced authentication protocols. This focus on security helps prepare businesses to counteract potential threats in a landscape where cyber attacks are increasingly sophisticated.

Moreover, the switch is equipped with a user-friendly management interface, which simplifies the process of monitoring and configuring network settings. This is complemented by support for SNMP and RMON, allowing network administrators to leverage tools for effective performance monitoring.

In summary, the ZyXEL Metrogigabit switch is an essential tool for organizations seeking robust performance, reliability, and security in their networking infrastructure. With its high-density ports, flexible configuration options, and comprehensive management features, it provides a strong foundation for building efficient and scalable networks. Whether for service providers or enterprises, this switch stands out as a reliable choice in the fast-evolving technological landscape.
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