Cabletron Systems MMAC-Plus 9T125-24 User Manual

Also see for SmartSwitch 9000: Reference guide Appendix Appendix Appendix User guide

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Cabletron Systems MMAC-Plus 9T125-24 User Manual Manual pdf 21 page image

3-3OperationIn order for source routing to work, the source station must determine the properroute to reach the desired destination. To accomplish this:1. The source station sends out frames called All Route Explorer (ARE) or SingleRoute Explorer (SRE) frames onto the network. All Source Route Bridgesrecognize these frames and forwards them to their outbound ports.2. The receiving bridges append their own route information to the RouteInformation Field (RIF) in the MAC frame header and transmit the frameagain.3. Eventually, the original source device receives all of the ARE replies from theother end stations on the network.4. From this information, the source device can determine a desired route foreach frame it transmits.Spanning Tree AlgorithmThe 9T125-24 promotes maximum network use in multiple bridge environments.A bridge learns the bridge topology of its network from bridge protocol data thatit receives from other bridges within the network. The bridges then apply theSpanning Tree Algorithm (STA) to select a root bridge, and then determineprimary data paths within potential data loop configurations.Spanning Tree Algorithm is a hierarchy (or tree) of priorities that bridges establishbetween themselves. This hierarchy guarantees that primary and redundant datapaths are clearly defined at all times, so that the network is continuously availableto users.In a multiple bridge environment, one bridge in the network establishes itself asthe root bridge. As the root, this bridge has priority over all other bridges. In aSpanning Tree, all of the bridges must determine which bridge is the root, andthen determine their own relative priority within the network.Flexible Network Bus (FNB)The FNB consists of two dual FDDI networks, the FNB-1 and FNB-2, providingup to 400 Mbps of data bandwidth. These FDDI networks are 100% ANSIFDDI-compliant supporting SMT (version 7.3), MAC, PHY, and PMD standards.This allows the FNB to traverse multiple SmartSwitch 9000 hubs, or connect toany ANSI FDDI-compliant device, through standard A/B port connections, usingthe FDDI repeater module.