Cisco NM-4B-S/T= Network Switch Component Networking

The 4- and 8-port ISDN BRI network modules provide various port densities for ISDN BRI connectivity. The optional, integrated NT1 allows consolidated customer premises equipment (CPE) to provide multifunction dial access server, router, and other capabilities within power branch office environments.

Four versions of ISDN BRI network modules are available. Each 4- and 8-port module has the option of an S/T interface or an onboard NT1 for each port. Local static RAM (SRAM) is used for buffer descriptors and input queues. The 4-port module is not field upgradeable to the 8-port module. With all eight BRI ports running continuous data (144 kbps each) and 50-byte packets, the maximum performance possible is 5760 pps and an aggregate full-duplex data rate of 2.3 Mbps.