Ref: 99980067 Title: New Products/Broadband Network Systems Date: 8/1/86 Copyright 3Com Corporation, 1991. All rights reserved. Overview The Bridge Communications Broadband products provide multi-vendor communications in pure broadband and hybrid broadband/baseband applications. They use 5M bps, Carrier Sense Multiple Access/ Collision Detection (CSMA/CC) local area network (LAN) technology on a single 6MHz channel. Bridge's Broadband servers use the Transmission Control Protocol/ Internet Protocol (TCP/iP) high-leve protocols. They provide network access to a wide variety of devices and offer interoperability in multi-vendor environments. Multiple data channels can be established to allow separate networks to share the same physical cable, yielding a very high aggregate data rate. These multiple channels can include other broadband services such as video and voice on other data channels. The Bridge Broadband frequency allocations is compatible with the IEEE 802 standard. The network can also operate on a midsplit or highsplit cable plant up to 10 miles long. Bridge Modems are frequency agile and support six channel pairs; they use duo- binary Amplitude Modulation Phase Shifted Key (AM PSK) modulation. These modems can be configured for single-cable or dual-cable translated systems. Features * Provides communication and resource sharing between terminals, workstations, personal computers, peripherals, and host computers. * Connects Ethernet segments through a broadband backbone that operates independently of high-level protocols. * Supports speeds up to 5M bps and implements full CSMA/CD. In addition, the channl remodulator detects collisions for the entire network. * Provides compatability with all of Bridge's TCP/IP Ethernet products, including network control servers for bootloading, configuration management, monitoring, and control. * Offers self-adjusting modems that eliminate much of the routine alignment and maintenance associated with a broadband cable plant. Operating frequency is software controlled for reconfiguration ease and sparing. * Includes closed-loop control mechanism allowing Bridge Modem self-adjust transmit signal levels to compensate for changes in the environment; therefore, the Bridge network stays operational when others may fail. * Permits the broadband modem transmitter to shut itself off after a timer expires to prevent malfunctioning equipment from transmitting continuously. The Bridge Communications Broadband Network System consists of the Internetworking Bridge/1, Communications Server/200-B, Communications Server/1-B, RFM/5 Modem, and CR/5 Channel Remodulator. The following list describes these broadband products in more detail. .h1;Internetwork Bridge/1 Overview The IB/1 is a high-performance broadband-to-baseband internetwork bridge that provides protocol-transparent routing. It interconnects a standard Ethernet (IEEE 802.3) and Bridge's 5M bps CSMA/CD Broadband network to form an extended campus hybrid network that covers a radius of up to 10 mles. The IB/1 is a data link level (ISO Layer 2) bridge that routes packets based on Ethernet addresses only. It continuously monitors traffic on the LAN, filters and discards messages addressed to local stations, and forward any inter-LAN packets. It can pass data between a baseband Ethernet and a broadband network even when they are running incompatible high-level protocol sets such as XNA, TCP/IP, DECnet, or ISO. Features The IB/1 and IB/2 run the same software. Therefore, the following features apply to both the IB/1 and IB/2. * A programmable, generalized filtering capability to isolate excess inter-LAN traffic and to protect network security. In addition, customer filers can be set up to discard packets based on Ethernet addresses. They can also be set up to filter traffic based on arbitrary masks on any packet byte, word, or double words. This feature allows the network manager to fine-tune network performance and to restrict internetwork access by user stations. * An integrated network management system. Users can access network management functions through a local console port or through Bridge's XNS-based Communications Servers. * System parameters, routing information, and performance and throughput statistics can be set, specified, or displayed via the user interface commands. * Continuous adaptive learning of the network configuration. The IB recognized the local and remote status of the stations. This feature greatly simplifies the installation and reconfiguration of network stations. * Operation at the data link level as well as protocol transparency. A multi-vendor network can be set up to pass data between a standard Ethernet and Bridge's Broadband network. * With the addition of a Multiport Transceiver Unit (MTU), the IB/1 becomes a Multiport Bridge/1, which can be used as a front-end for up to seven Ethernet-compatible hosts and devices on the broadband network. * With the multiple high-speed 68000 processors, the IB filters local traffic at up to 7,000 packets per second and forward inter-LAN traffic up to 2,500 packets per second. * Fully compatible with the entire Bridge family of Communications Servers, Gateway Servers, PC network products. and Network Control Servers. .h1;Communications Server/1-B The CS/1-B is a Communications Server that is installed on the broadband network. Since its hardware is based on a standard CS/ 1, the CS/1-B can connect up to 64 asynchronous terminals, 3270 terminals, PCs, printer, modems, or host ports to the Bridge broadband network. The hardware interface options include RS- 232, RS-422, and 3270 Category A coax. The CS/1-B can be a disk-based on diskless unit. For the diskless unit, operating software is loaded from a Bridge NCS/150 across the Internetwork Bridge/1. The CS/1-B supports the audit trail server, which gathers and records session information such as conections attempted, whether successfully completed, unsuccessful, or disconnected. The CS/1-B runs standard TCP/IP software; therefore, it has the same features as other Bridge TCP/IP products. .h1;Communicaitons Server/200-B The CS/200-B is a compact, diskless Communications Server that connects four or ten RS-232 interface terminals, personal computers, printers, modems, or host ports to the Bridge Broadband network. The CS/200-B runs TCP/IP software. Its operating software is loaded from a Bridge NCS/150 across the Internetwork Bridge/1. The CS/200-B supports the audit trail service, which gathers and records session information such as connections attempted, whether successfully completed, unsuccessfuly, or disconnected. The CS/1-B and CS/200-B require an RFM/5 to connect to the broadband network. Refer to the RF Modem/5 section or a more detailed description of the RFM/5. .h1;TCP/IP Features The CS/1-B and CS/200-B described above are based on TCP/IP protocols. Bridge's TCP/IP implementation includes the following features. * Server Telnet and User Telnet support. * Subnet support. * Passive-end or host-side RLOGIN. The RLOGIN feature allows a login from a UNIX host to a non-UNIX host front-ended by the CS/1-B. * Primary and secondard name server support. This feature allows the secondary name server to be queried if the primary name server does not yield a name to address resolution. * Default gateway support. This feature allows all remote network packets to be sent to a specified gateway. The gateway, however, should be able to return an Internet Control Message Protocol (ICMP) REDIRECT if it is not the optimal first hop. * The number of physical ports can be limited via the system generation program allowing the number of shared sessions per port to be increased. * The amount of system buffer allocated during initialization time can be controlled via the system generation program. * Permanent Virtual Circuits support allowing automatic circuit reestablishment upon disconnection. Note that this feature is only available in the CS/200 and CS/200-B. * Service Port Listener support allowing the TCP interface to be exported to the serial line. Refer to Application Note number 12 for more detailed descriptions of these service ports. .h1;RF Modem/5 The RFM/5 is an external, frequency-agile modem that connects a communications server or internetwork bridge to the broadband cable and is powered by the server. One of six operating channel pairs can be selected through software commands. The modem supports adjacent channel operation to maximize use of the cable bandwidth. It also provides connections for single- or dual- cable translataed systems. Directed by the channel remodulator, the microprocessor- controlled RFM/5 will automatically and continuously self-adjust transmit levels to compensate for environemtnal changes. The Channel Remodulator/5 (CR/5) measures the signal levels of each incoming packet, and sends a command to the transmitting modem to increase or decrease the level whenever it drifts outside the selected range. This self-correcting feature makes the Bridge Broadband network ideal for applications where up-time is critical, and also greatly simplifies routine broadband maintenance. A jabber-inhibit feature automatically turns off the modem transmitter when the maximum transmit time is up. This prevents a malfunctioning station from transmitting continuously and tying up the entire channel. The modem can also be taken off-line remotely. .h1;Channel Remodulatoor/5 The CR/5 is located at the cable headend to handle frequency translation and packet regeneration for each Bridge Broadband channel, filtering out any noise in the process. The CR/5 detects collisions for the broadband network. It examines each incoming packet for framing errors or illegal bit transitions. To allow collision detection, the CR/5 broadcasts a jamming signal to alert all modems so that the CSMA/CD protocol can operate effectively.