Cabletron Systems CSX200 CyberSWITCH Installation Manual

Also see for CSX200 CyberSWITCH: Setup guide User guide Configuration guide User guide

Contents

CSX200 Firmware SupportCSX200 Installation Guide2-5Firmware Data CompressionThe STAC Electronics Stacker LZS Compression algorithm provides a minimum of 2:1 firmwaredata compression for the CSX200 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 (whichconforms to the applicable standards), must be in use at both ends of the WAN link. This methodof data compression is used as the default, if the hardware compression module is not installed.HDLCHigh-level Data Link Control (HDLC) protocol is used in conjunction with the WPIM-HDSL toconserve WAN bandwidth between two compatible devices, over a point-to-point connection. TheHDLC (RAW) protocol reduces the amount of overhead information that needs to be containedwithin each data packet to direct it to its destination. This decreased packet overhead providesmore available bandwidth to transfer data.DHCP and NATThe Dynamic Host Configuration Protocol (DHCP) and Network Address Translation (NAT)schemes eliminate the expense of purchasing limited public IP addresses for each client on a localnetwork, and the need to re-configure a client if it is moved to a different network.The CSX200 acts as a DHCP server that lets individual clients (PCs, network equipment) taketurns using a range of private IP addresses (often referred to as local IP addresses), and providesoptional secondary setup features for these clients on a per-port basis. A private or “local” networkis referred to as a sub network that is using private or “local” IP addresses. An “outside” networkrefers to a Wide Area Network (WAN) commonly known as an Internet. An Intranet is an“Internet” in use on a facility or campus where registered public IP addresses are required.The CSX200 distributes these addresses on a first-come-first-served basis, dynamically assigning alocal IP address to an individual client (from 253 available addresses). This local IP address is then“leased” for a predetermined amount of time, configured for a particular port. Each Ethernet portprovides DHCP services for one Class C subnet and secondary setup features for individual clientsthat support the use of a default gateway, domain name and WINs server. On the Wide AreaNetwork (WAN) side, the Network Address Translation (NAT) routing scheme lets clients withlocal IP addresses use the public IP address(es) of the CSX200 WAN interface(s) to access theWAN.NAT lets several DHCP clients on a sub network connect to WAN clients by letting the DHCPclients share a single public IP address. The NAT scheme modifies the IP headers and addresses,and the selected fields in upper layer protocol headers.