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Mapping Network Device Functions to the OSI Reference Model
Published in James Aweya, Designing Switch/Routers, 2023
The purpose of STP and its newer variants (RSTP and MSTP) is to identify and temporarily block the ports creating loops in a network segment or VLAN to prevent the flooding problem described above. The switches run STP which supports loop prevention mechanisms. Part of the loop prevention mechanisms involves electing a root bridge or switch. STP (and its variants) creates a logical loop-free topology of the LAN, called a spanning tree, from the root bridge. The other switches in the LAN segment measure their distance from the root switch and if there is more than one path to get to the root switch, then it can safely be assumed that there is a loop. The switches use STP to determine which ports should be blocked to break the loop and create a Spanning Tree for the LAN.
High-Performance Switch-Routers
Published in James Aweya, Designing Switch/Routers, 2023
MSTP was developed to provide an efficient means of supporting multiple instances of Spanning Tree (ST) as would be required for deploying numerous VLANs in a switched Ethernet LAN. Instead of a separate instance of ST for each VLAN, MSTP allows a group of VLANs to share a common instance of ST. MSTP allows the formation of Multiple Spanning Tree (MST) regions that can run Multiple MST Instances (MSTI). Multiple regions and other STP bridges are interconnected using one single Common Spanning Tree (CST). Enhanced Spanning Tree features such as Root Guard and Bridge Protocol Data Unit (BPDU) Guard prevent rogue hijacking of a Spanning Tree root and maintain a contention and loop-free environment especially during dynamic network deployments.
Spanning Tree Protocol
Published in Iannone Eugenio, Telecommunication Networks, 2017
The spanning tree protocol (STP) is a link-management protocol that is part of the Institute of Electrical and Electronics Engineers (IEEE) 802.1 standard for bridges and switches. All the material of this appendix is a synthesis of IEEE Ethernet standards, so we will not repeat here the list of such standards, recommending the interested reader to use the list in the references of Chapter 3.
Smart grid mechanism for green energy management: A comprehensive review
Published in International Journal of Green Energy, 2023
Adila Fakhar, Ahmed M.A. Haidar, M.O. Abdullah, Narottam Das
The long-distance wireless communication from customers to the local utility has several drawbacks, such as limited bandwidth, considerable costs, and unstable quality of connection. Unlike wireless communication, the wired communication network enhances the security of the system and can provide reliable communication with accurate data transmission (Stefano, Scaglione, and Wang 2010). Although the uncertainty in the effectiveness of Ethernet for real-time substation automation has been investigated in many research studies, the application of Ethernet in distribution power systems considering the random characteristics of RER was not sufficiently reported. For substation communication networks, the Ethernet technology must comply with the IEC 61850 global standards. One of the specified requirements for time-critical applications is 10 msec in distribution substations while 3–4 msec in transmission substations. The coverage for communication in the distribution substation is (25–150) m whereas in the transmission substation is in the range of (50–300) m (Shuo et al. 2017). The spanning tree protocol (STP) as defined in the IEEE standard 802.1D was designed to solve the main problem of traffic and prevent accidental loops in the poorly structured and managed wiring closets. To pave the way for smart grid application, the mature technology of narrowband PLC standardization (IEEE P1901.2 with ITU-T G.hnem) which is still in service can be upgraded to the ITU-T G.hn and IEEE P1901 with the expanded Home Plug AV2 specification (Hadlach et al. 2017). Generally, the PLC comprises of two types, Narrowband PLC (NB-PLC) and Broadband PLC (BB-PLC). They are differentiated and classified based on the frequency range and transmission distance of signals as demonstrated in Table 10 (Haidar et al. 2011; Tonello et al. 2011). The NB-PLC is mainly suggested for the automation in smart grid application, this is due to its ability to communicate through transformers with bypass installment as it has a lower frequency range (Galli, Scaglione, and Wang 2011). Here, the automated systems do not require any additional communication network and can be used to control devices (lighting and heating systems), central control of home (doors and windows), and for security purposes. On the other hand, the major drawbacks of PLC are the noise and attenuation in the channel causing distortion and delay in transmitting the signal (Uribe-Pérez et al. 2017). Considering the characteristics of PLC, digital modulation techniques, that is, frequency shift keying, amplitude shift keying, and phase shift keying are more suitable than analog modulation techniques (Franek and Fiedler 2017). The major problem when using the amplitude shift keying in PLC is the noise susceptibility which may deteriorate the system performance (Haidar, Fakhar, and Muttaqi 2020).