DTJ Number 3 September 1987 - Digital Technical Journals

New ProductsIMC6BOOOMICROPROCESSORII IBINARYROMMEMORYSEARCH LANCE LANCECONTROLCONTROLRAMNVRAMETHERNETADDRESSRAMIPACKETRAMFigure 6extended network with as many as 8000 activestations. Up to eight Ethernets may be interconnectedin series (22,400 meters of cable) . Aggregatebandwidth will increase proportionally withevery added Ethernet, and usable bandwidth willalso increase substantially in many applicationenvironments.The Extended IAN Architecture itself is nowa key part of Digital's networking strategy.As exemplified in the LANBridge 100, thisarchitecture permits substantial expansion inthe physical limits of a given IAN technology.These physical dimensions include geographicextent, number of stations, and aggregate bandwidth.Bridges implementing the ExtendedLAN Architecture also provide increasedavailability as a result of the spanning treealgorithm and the standby operation mode. Thetransparent operation of high-performancebridges enhances significantly the capabilitiesand services offered by both Digital and non­Digital equipment.The Extended IAN Architecture also provides aunifying mechanism in networks composed ofmultiple homogeneous or heterogeneous IANs.The bridge concept may be extended to interconnectIANs with different physical layers, suchas baseband and broadband Ethernet. Within certainconstraints, it may also be used to interconnectdissimilar IANs.ETHERNETLAN'riETH E RNETLANHigh-level Block Diagram with MC68000 jIiThe origins of the LANBridge 100 and theExtended IAN Architecture may be traced to aproject whose original goals only vaguely recognizedthe need for such a mechanism. Both theproduct and architecture are the result of gatheringand analyzing customer requirements, followedby applying innovative design techniques.AcknowledgmentsThe authors would like to acknowledge the othermembers of the original p;roject team. In addition,the work of Bob Shelley and Tony Robillardwas instrumental in the deign and constructionof the bridge breadboard. Tony Lauck, RadiaPerlman, George Varghese, ! Mike Soha, as well asthe the entire LANBridge 1 00 development teamIprovided invaluable additions and insight to thearchitectural process.References1. B. Stewart and W. Hawe, "Local Area NetworkApplications," Telecommunications(September, 1984): 96f-96u.2. IEEE Project 802 Local Area NetworkStandards , "IEEE Standard 802.3 CSMA/CD Access Method and Physical LayerSpecifications," Approved IEEE Standard802.3-1985, ISO/DIS 8802/3 (July'1983).'IDtgttal TecbntcalJournalNo. 3 September 198671