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HSIM-W87 User’s Guide 1-5
The primary function of the HSIM-W87 is to provide LAN to WAN
access. WAN physical connectivity will be supported through the use of a
T3 interface with an unbalanced 75 ohm coaxial cable pair. LAN to WAN
connectivity will be supported through HDLC and T1 Inverse
Multiplexing (IMUX).
The HSIM-W87 interoperates with those Cabletron Systems WAN
products that support raw HDLC as the WAN protocol. This support is
limited to the CyberSWITCH product line which supports HDLC:
• CSX400 – Version 02.00.15 or higher
• HSIM-W6 – Version 02.00.15 or higher
• HSIM-W84 – Version 02.00.xx or higher
• HSIM-W85 – Version 02.00.xx or higher
1.4.2 HDLC
The High-level Data Link Control (HDLC) protocol is used in
conjunction with the Inverse Multiplexing (IMUX) feature to conserve a
user’s WAN bandwidth between two Cabletron Systems products, over a
point-to-point connection. Cabletron Systems products such as the
HSIM-W6, HSIM-W84, HSIM-W85, HSIM-W87, and CSX400 must be
in use on both ends of the WAN link for these functions to work. The
HDLC (RAW) protocol reduces the amount of overhead information that
needs to be contained within each data packet to direct it to its destination.
This decreased packet overhead provides the IMUX functions with more
bandwidth to transfer user data.
1.4.3 Inverse Multiplexing (IMUX)
Cabletron Systems Inverse Multiplexing (IMUX) feature provides
enhanced throughput for users by doing the following:
• The IMUX function evenly distributes a data packet stream from the
LAN interface through multiple full T1 WAN interfaces on the
HSIM-W87.
• Data packet streams received by the WAN interfaces on the other end
of the WAN links are then recombined, ordered, and transmitted to the
LAN interface.