Cabletron Systems SmartSwitch 9000 User Manual

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

Cabletron Systems SmartSwitch 9000 User Manual Manual pdf 24 page image

Operation3-4SR-TB BridgingSR-TB Bridging is only between the front panel Token Ring and the backplaneFNB. Source Routing (SR) packets from the front panel Token Ring must beconverted to Transparent Bridging (TB) type packets before it is sent over theFNB. The RIF is stripped off the packet and placed in a RIF cache.The SR-TB bridge is a learning type bridge. It learns what nodes are present bylistening to incoming packets and saving their MAC addresses to a databasetable. If the packet is source routed, it also updates the RIF cache.If the destination is unknown or is a broadcast address, the bridge sends either aSTE or ARE packet for the Token Ring interface, or a TP packet for the FDDIinterface, to carry the data to the end station. This is user configurable.Spanning Tree AlgorithmThe 9T125-08 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.