Cabletron Systems TRXMIM-24A User Manual

Also see for TRRMIM-2AT: Installation guide

Contents

Cabletron Systems TRXMIM-24A User Manual Manual pdf 51 page image

Page A-1APPENDIX AINTRODUCTION TO FOUR-RINGFNB FUNCTIONALITYA.1 IntroductionThis appendix addresses only Token Ring network applications. Itis intended to introduce and explain the closely related concepts ofport switching and the four-ring Flexible Network Bus (FNB).These concepts reflect recent developments essential to the basicfunctionality of a number of Cabletron products. An understandingof these concepts is essential to the full operation of all portswitching Token Ring Media Interface Modules (e.g., TRXMIM,TDRMIM) and all Management Modules (e.g., TRMM-2) thatsupport port switching.A.2 The Flexible Network Bus (FNB)The FNB is a data bus which spans the entire width of thebackplane of the Multi Media Access Center (MMAC), providingRing In / Ring Out connections between each module and formingcontinuous channels for the inter-communication of data betweenmodules within the MMAC.A.3 FNB Operations Without Port SwitchingCreation of Multiple FNB RingsIn normal Token Ring applications, when using Media InterfaceModules (MIMs) that do not support port switching (such asTRMIM and TRRMIM), the FNB serves as a single Token RingLAN. Each Media Interface Module (MIM) in the MMAC mayattach to this single LAN and operate together; or MIMs with left/