Chapter 2: About the HSIM-W610 HSIM-W6 User’s GuideInverse MultiplexingCabletron Systems Inverse Multiplexing (IMUX) feature provides enhanced throughput for usersby doing each of the following:• The IMUX function evenly distributes a data packet stream from the LAN interface through thetwo WAN interfaces on the HSIM-W6. Since the data traffic is equally shared between the twoFull T1 interfaces, each with 1.5 Mbps throughput, the total throughput over the logical link is3 Mbps, or 6 Mbps full-duplex operation with the optional hardware compression module(CSX-COMP/ENCR) installed in the HSIM-W6.• The IMUX function passes packet sequence information over the WAN using the Point-to-PointProtocol (PPP) to support data coherency on both ends of the link.• Data packet streams received by the WAN interfaces on the other end of the WAN link are thenrecombined, ordered, and transmitted to the LAN interface.• The IMUX function is fully configurable using QuickSET, which is discussed in the Bridgingand Routing Configuration section of Chapter 4 and the MIB Navigator command setdiscussed in Chapter 6.Firmware Data CompressionThe STAC Electronics Stacker LZS Compression algorithm provides a minimum of 2:1 firmwaredata compression for the HSIM-W6 over PPP and Frame Relay. Firmware data compression issupported in software on each WAN interface for line speeds of up to 256 Kbps per WPIM, whichis equivalent to four DS0 channels. To use data compression, compatible equipment, (such as theHSIM-W6, CSX400, and CSX200 or other vendors’ equipment which conforms to the applicablestandards), must be in use at both ends of the WAN link. This firmware method of datacompression is used as the default, if the hardware compression module is not installed.NOTECabletron Systems products that support Inverse Multiplexing (IMUX), such as theHSIM-W6, CSX400, and HSIM-4T1, must exist on both ends of the WAN link for theIMUX function to work.Both bridging and routing functions are disabled when using the IMUX function.
