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All Routes Broadcast (ARB): A communication that is addressed to all of the LANs on an internetwork or to all the segments of a virtual LAN.
The Catalyst 1600 buffers each ARB frame into memory, then copies it to each Token Ring port. Each Token Ring port updates the Routing Information Field (RIF) of the frame in memory with the bridge number and ring number, to reflect that the frame has been copied to the attached ring.
beaconing: A warning signal that a Token Ring station sends to all the other stations on the ring when it detects a hard error on the ring.
boot microcode: The firmware for booting and initialization that resides in the Catalyst 1600 system ROM. When you want to upgrade the firmware, instead of replacing the system ROM, you can download new software using TrueView Catalyst 1600 Manager.
You can obtain upgrade Madge software and firmware from the Madge Bulletin Board System (BBS).
bridge: A device that connects one LAN to another at the Datalink Layer of the OSI model. The two main types of bridges are source-routing bridges and transparent bridges. The traditional method for connecting multiple Token Ring networks is by using a source-routing bridge.
bridge number: A single hexadecimal number in the range 0 through F, that is combined with the ring numbers of the two Token Ring networks that are connected by a bridge to uniquely identify the bridge.
bridge priority: Determines which one of two or more parallel bridges connecting the same two Token Rings is able to forward single-route broadcast frames at any one time. Inserting a lower number increases the priority of the device and the probability that it will be selected as the root bridge.
The bridge root priority applies when the spanning tree mode is set to Auto.
broadcast filtering: The method by which the Catalyst 1600 restricts broadcast frames to a group of rings defined by the user.
broadcast frames: Frames that are addressed to multiple devices on an internetwork. The Catalyst 1600 can forward broadcast frames efficiently by transmitting frames simultaneously on multiple Token Ring ports.
Catalyst 1600: A source-routing Token Ring switch that supports the connection of wiring concentrators or lobe stations over either UTP or STP media at ring speeds of 4- or 16Mbps.
concentrator mode: The mode in which a Catalyst 1600 port behaves like a LAM port and detects the phantom drive signal that is generated when the connected device inserts.
hop count: The total number of bridge hops a broadcast frame can make. If a frame that has exceeded its hop count is passed to the Catalyst 1600, the frame is not forwarded.
impermeable virtual LAN: You can define impermeable virtual LANs by specifying an explicit list of the rings that belong to the virtual LAN.
Define impermeable virtual LANs when one or more Catalyst 1600 devices connect a number of Token Rings to form a large LAN.
IP address: A 32-bit integer address that is used in communications with a device on an IP network.
IPX network number: An eight-digit hexadecimal number in the range 00000001 through FFFFFFFF, that uniquely identifies a segment on an IPX network. IPX routers and servers connected to the same segment must use the same IPX network number to identify the segment.
Management Information Base (MIB): The database of management information that resides with a device that is managed via SNMP.
microcode: See boot code and run-time microcode.
node mode: The mode in which a Catalyst 1600 port behaves like an adapter card and generates a phantom drive signal to insert into the device that is connected.
non-broadcast frame: A frame that the Catalyst 1600 does not copy onto all of its ports or onto all the ports of a virtual LAN. If the ring and bridge numbers in the RIF match, the Catalyst 1600 forwards the frame to the output port using the cut-through technique if possible.
path cost: Determines the relative length of a path between two rings. The port path cost can be used to select the shortest and most efficient path.
The port path cost applies when the port spanning-tree mode is set to Auto.
permeable virtual LAN: You can define permeable virtual LANs by specifying a list of rings. Permeable virtual LANs do not restrict the forwarding of broadcast traffic to an explicit list of the rings.
Define permeable virtual LANs when Catalyst 1600 devices are installed in a large source routed network, to define logical workgroups without explicitly specifying the rings that belong to each virtual LAN.
ring number: A three-digit hexadecimal number in the range 001 through FFF, that identifies the Token Ring to which the port is attached.
router: A device that connects two or more LANs at the network layer of the OSI model.
Like bridges, routers operate in store-and-forward mode, buffering each packet into memory before determining the destination of the frame. Routers also amend the header on each frame once it has been buffered into memory, to reflect the routing decision that has been made.
Routing Information Field (RIF): The field in the header of an incoming frame that the Catalyst 1600 uses to determine the correct output port.
run-time microcode: The software that the Catalyst 1600 needs to enable it to perform switching functions. You can download upgrade software to the Catalyst 1600 using Catalyst 1600 Manager software.
Single-Route Broadcast (SRB): A communication addressed to all of the LANs on an internetwork or to all the segments of a virtual LAN.
The Catalyst 1600 buffers each SRB frame into memory, then copies it to the Token Ring port subject to defined virtual LANs. The Token Ring port updates the frame in memory with its ring number, to reflect that the frame has been copied to the attached ring.
SNMP: Simple Network Management Protocol. A protocol designed to enable network management programs to communicate with MIBs on networked devices.
source-routing bridge: A bridge that uses information in the header of each frame to establish a route between communicating devices on different LANs.
spanning tree algorithm: The method that determines which bridge forwards single-route broadcast frames onto each ring, and ensures that no single-route broadcast frames appear more than once on the same ring.
The Catalyst 1600 can use the IEEE spanning-tree algorithm to determine the best path of frames when there are multiple path routes in an internetwork.
subnet mask: A 32-bit integer address that defines how an IP address is divided into sub-network address and local host address portions.
switching: Like bridging, switching provides a connection between LAN segments. However, a cut-through switch, such as the Catalyst 1600, forwards packets on direct connections between the input and output ports, without buffering them into memory.
Telnet: The IP terminal emulation protocol that you can use to connect a terminal device to the Catalyst 1600. You cannot use the serial interface to set up virtual LANs.
virtual LAN: A virtual LAN consists of two or more Token Ring7 segments that are joined by Catalyst 1600 devices, where stations can only make connections to other stations or servers that are part of the same virtual LAN. Therefore, broadcast traffic originating on any ring is only received by stations on rings that belong to the same virtual LAN.
Through the definition of virtual LANs, you can reduce the proportion of bandwidth occupied by broadcast traffic and reduce the possibility of broadcast storms, make future moves and changes easier to support, and improve network security.
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