About the CSX40010 CSX400 and CSX400-DC User’s GuideFirmware Data CompressionThe STAC Electronics Stacker LZS Compression algorithm provides a minimum of 2:1 firmwaredata compression for the CSX400 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 theCSX400, CSX200, and HSIM-W6 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.Inverse Multiplexing (IMUX)Cabletron 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 CSX400. 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 CSX400.• The IMUX function passes packet sequence information over the WAN using the Point-to PointProtocol (PPP) and a WAN Encapsulated Ethernet Frame Type to support data coherency onboth ends of the link.• Data packet streams received by the WAN Interfaces on the CSX400 at the other end of theWAN link are then recombined, ordered, and transmitted to the Ethernet 1 interface.• The IMUX function is fully configurable using QuickSET, which is discussed in the Bridgingand Routing Configuration section of Chapter 7 and the MIB Navigator command set inChapter 9.NOTECabletron Systems products that support IMUX, such as the CSX400, HSIM-W6 andHSIM-4T1, must exist on both ends of the WAN link for the IMUX function to work.Both bridging and routing functions are disabled when using the IMUX function.
