MU9C8148

• Supports High-speed Source Routing or Source Routing Transparent Bridging for up to eight ports
• Glue-free operation with the MUSIC MU9C1480 LANCAM and Texas Instruments' Token Ring chip set
• Configurable for either Motorola or Intel processor addressing modes
• Complies with the IEEE standards for 4 and 16 Mb/s Token Ring
• Contains a 128-entry Instruction Buffer that holds up to seven down-loadable filtering and purging routines, which can be automatically or directly invoked
• Automatically selects Source Routed or Transparent filtering routines based on Transceiver output data, and supplies the proper Match, Fail, or Flush signals to the MAC chips
• Built-in arbitration allows two MU9C8148s to share a central LANCAM database
• Selectable filtering options for each frame type
• Frame validity is checked on all Routing Information Fields
• Manufactured in CMOS technology
• Available in 68-pin PLCC package and 80-pin TQFP package

The MU9C8148 is a Source Routing Transparent (SRT) Interface for the MUSIC Semiconductors MU9C1480 LANCAM for use in Token Ring LAN Bridges and Brouters. This interface operates in accordance with IEEE standards while supporting address filtering rates up to 150,000 frames/sec for minimum-length frames.

The MU9C8148 has four interfaces to provide glue-free address filtering. The Transceiver interface monitors receive data from the Transceiver to the MAC, and determines whether to filter according to Source Routing or Transparent Bridging standards. The MAC interface supplies Match, Fail, and Flush signals to instruct the Token Ring controller to reject or copy a frame. The LANCAM interface controls the companion LANCAM(s) for Transparent filtering. The Host Processor interface allows for direct initialization of the MU9C8148, and downloading of the filtering and purging routines, to offload the communication processor.

The MU9C8148 can choose to copy or reject a frame depending on the frame type (MAC, LLC, or reserved), and can perform multiple validity checks on the Routing Information Field (RIF), including general checks on every Routing Control Field (RCF), as well as multiple frame related checks.

The Instruction Buffer can be loaded with up to 128 instructions at initialization for the LANCAM routines such as matching, learning,aging, purging, and data buffering operations. Internal arbitration controls access to the LANCAM. Separate arbitration pins allow two MU9C8148s to easily form a dual-port Bridge by sharing a central LANCAM-based station list.

With seven Ring-Bridge-Ring number combinations stored internally,the MU9C8148 can also operate as a source routing accelerator in multi-port Token Ring Bridge/Brouter environments.