Miscellaneous/Multiprotocol11-31Product DescriptionsMiscellaneous/MultiprotocolETWMIM: Ethernet/Token Ring/Wide Area Bridge ModuleCRM-3E: Cisco Router Module with Ethernet Backplane ConnectionThe ETWMIM provides bridging between Token Ring and Ethernet networks aswell as connectivity to remote sites across a WAN. When installed in yourcentral office hub the ETWMIM, with optional T1-SRM module, is capable ofbranching out to as many as 24 remote office sites.The ETWMIM is equipped with two WAN ports: one synchronous interface forconnection to lower speed Digital Data Services (DDS) or T1/E1 circuit throughan external DSU/CSU; and an optional T1 module, the T1-SRM. The T1-SRMhas a built-in DSU/CSU for direct connection to a T1 or fractional T1 supportingaccess for up to 24 remote locations by using time slot multiplexing.The ETWMIM communicates on Ethernet Channel A across the backplane of theMMAC, and Ethernet Channels B or C through the Ethernet Port InterfaceModule (EPIM). EPIMs are user-installable from the face panel of the ETWMIMand are hot swappable to eliminate network downtime when changing mediatypes. Connection to the Token Ring network is provided through the FlexibleNetwork Bus (FNB) on the backplane.The CRM-3E is a router specially designed for the MMAC that utilizesEthernet Channel A, B, or C from the backplane of the MMAC. TheCRM-3E runs the industry-leading routing software of Cisco Systems,and can provide remote locations with several internetworkingbenefits, including access authentication for security and headercompression, and priority queuing for improved bandwidthutilization. Two slots, which may be configured with Network ProcessModules (NPMs), provide the CRM-3E with support for severalcombinations of Ethernet, Token Ring, Wide Area (serial), FDDI andISDN interfaces – all on a single platform.The CRM-3E takes up two slots in the MMAC chassis and requires thepurchase of NPM modules to provide routed ports.