Cabletron Systems SmartSTACK ELS100-S24TX2M User Manual

Also see for SmartSTACK ELS100-S24TX2M: Quick installation guide Quick installation guide Management guide

Contents

9033260-01 Product Overview 7Feature SummariesThe following summaries describe ELS100-S24TX2M features in areassuch as standards compliance, functionality, performance, and options.IEEE 802.1D BridgeThe ELS100-S24TX2M switch is fully compliant with IEEE 802.1Dtransparent bridging specifications. An address table is provided forlearning, filtering, and forwarding. The switch can support up to amaximum of 8K addresses. Addresses are automatically learned by theswitch, and can be individually assigned specific forwarding treatment bythe network administrator if desired. Forwarding table configuration canbe made out-of-band via the console interface or in-band via SNMP orTelnet. Static and dynamic addresses are both stored in this table. Onestatic address is assigned per port by default. The Static Unicast AddressTable Configuration screen in the console menus allows you to assignadditional static addresses if required.Spanning Tree ProtocolThe ELS100-S24TX2M switch supports the IEEE 802.1D Spanning TreeProtocol. This protocol allows redundant connections to be createdbetween different LAN segments for purposes of fault tolerance. Two ormore physical paths between different segments can be created throughthe switch, with the Spanning Tree Protocol choosing a single path at anygiven time and disabling all others. If the chosen path fails for any reason,a disabled alternative is activated, thereby maintaining the connection.This prevents network traffic from circulating in an endless loop formed bymultiple connections to the same LAN segment.Spanning Tree parameters are configurable using the Spanning TreeConfiguration Menu of the console menus, the on-board Web agent, orvia SNMP (see Appendix B, “Spanning Tree Concepts,” in theManagement Guide for more information).Frame Buffering and Frame LatencyThe ELS100-S24TX2M switch is a store-and-forward switching device.Each frame is copied into switch memory before being forwarded toanother port. This method ensures that all forwarded frames conform to astandard Ethernet frame size and have a correct cyclic redundancy check(CRC) for data integrity. This switching method prevents bad frames fromtraversing the network and using up valuable network bandwidth, as withcut-through switching technology.To minimize the possibility of dropping frames on congested ports, theELS100-S24TX2M switch provides 128 KB of frame buffering per port.This buffer space is used to queue packets for transmission on congestednetworks. This is an additional advantage over cut-through switchingtechnology, which drops packets immediately when experiencingcollisions.