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The Cisco Systems Catalyst 3900 is a second-generation Token Ring switch that combines unsurpassed performance and functionality with a cost-effective price, ideally suited for desktop connectivity. The Catalyst 3900 comes with 20 fixed ports and a unique FlexSlot that can accommodate two expansion modules or, in the future, one double-wide module. Available expansion modules include a 1-port ATM OC-3c uplink, a 2-port fiber and copper Inter-Switch Link (ISL) uplink for Token Ring transport over Fast Ethernet, a 4-port fiber Token Ring module, and a 4-port copper Token Ring module. The Catalyst 3900 switch also offers an optional Stack Port module that enables up to eight units to be stacked together using the Catalyst Matrix switch.
To address the needs of delay-sensitive data, such as multimedia, this switching fabric contains two priority data queues that can be set by the user. By default, frames assigned a priority of 5, 6, or 7, such as multimedia transmissions, are sent to the high-priority queue and given forwarding preference. Frames assigned a priority of 4 or lower are processed through the normal-priority queue.
For a bandwidth boost, SRS and dynamic ring learning enable the Catalyst 3900 switch to easily replace an existing Token Ring hub or media access unit (MAU) with no configuration required. In the presence of source-routed traffic, the Catalyst 3900 automatically learns its ring number and forwards frames to downstream bridges based on next-hop information in the Routing Information Field (RIF). Non-source routed (NSR) frames are transparently bridged. There is no need to reconfigure your existing network numbering plan when adding the Catalyst 3900 to the network infrastructure.
The Catalyst 3900 switch provides a wide range of connectivity options for maximum flexibility. Connecting a MAU, server, or end station is easy because the Catalyst 3900 enables direct station attachment and ring-in/ring-out (RI/RO) connections to scale ring segment size. Each Token Ring port supports Dedicated Token Ring (DTR), the IEEE standard that defines direct station attachment at 4, 16, or 32 Mbps. Furthermore, ports 19 and 20 support RI/RO connectivity in addition to DTR. The 4-port fiber module supports 802.5J for fiber lobe extension and ring in/ring out (RI/RO) in addition to the proprietary RI/RO signaling used by the IBM 8230.
Shielded RJ-45 ports support both 150-ohm shielded twisted-pair (STP) and 100-ohm unshielded twisted pair (UTP). There is no need for external media filters; nor is there a requirement for baluns to do impedance matching for different cable types.
Traffic filters that block or allow traffic are integrated into the bridging ASICs. As a result, enabling MAC address filtering on inbound ports and destination service access point (DSAP) and Subnetwork Attachment Point (SNAP) type filters on inbound and outbound ports has no effect on the media-rate performance of the switch. In addition, in configurations where SRT is used between ports or groups of ports, it is possible to control whether traffic is transparently bridged or source-route bridged on a per-protocol basis. This feature is ideal for environments that have redundant Systems Network Architecture (SNA) gateways and IP or IPX file servers that are not configured for SRB. With this capability, ports with SNA gateways can be configured to receive only SRB traffic, preserving the ability to have multiple gateways with the same MAC address, while also eliminating unnecessary transparently bridged traffic. Likewise, the switch ports with only IP or IPX servers can be configured to receive only the protocol traffic destined for them.
All-routes explorer reduction provides traffic control for networks with multiple user rings connected to dual-backbone segments. With this feature, when a client station sends an explorer frame, the switch forwards a copy of only one frame if it has not already been seen by the switch on any of its other ports. Therefore, in a dual-backbone configuration, each user ring receives only two copies of the broadcast. In this way, the client stations still learn backup paths to their servers, and the user rings are protected from unnecessary broadcast traffic. User-configurable broadcast thresholds are provided to protect end systems from excessive explorer traffic. Priority queues within the switch ensure that delay-sensitive traffic, such as multimedia applications, are forwarded first.
The Catalyst 3900 provides a wide range of options for a high-speed, scalable interconnection between switches. The ATM OC-3c uplink offers ATM Forum-compliant LAN Emulation 1.0. In addition, a frame-based alternative to ATM is provided by an ISL uplink that enables Token Ring transport over Fast Ethernet. A third alternative, available with the TokenChannel feature, allows you to group up to eight ports together as one logical port for up to 256 Mbps of bandwidth between switches.
Figure 8-10 shows the front view of the Catalyst 3900. Table 8-10 summarizes the features of the Catalyst 3900, and Table 8-11 lists the environmental specifications.
| Characteristic | Description |
|---|---|
| Ports | 20
1 FlexSlot that supports up to 2 expansion modules 1 EIA/TIA-232 console 1 stack port slot (rear) |
| Expansion modules | 4-port Token Ring fiber
4-port Token Ring copper 1-port ATM OC-3c 2-port 100BaseTX with ISL 2-port 100BaseFX with ISL |
| Front panel indicators | Base switch:
Port: insert, activity System power Mode Fault Stack port expansion module: Transmit Receive Attach |
| Buffers | 1-MB DRAM per group of 4 ports |
| Addresses | 6500 per group of 4 ports; 10,000 per system |
| Protocol compatibility | Transparent to higher-level protocols |
| Network management | MIB for Network Management of TCP/IP-Based Internets: MIB-II (RFC 1213)
Definitions of Managed Objects for Bridges (RFC 1493) Evolution of Interfaces Group of MIB-II (RFC 1573) Token Ring Extensions to the Managed Objects for SRB (RFC 1525) IEEE 802.5 Token Ring MIB (RFC 1748) RMON (RFC 1757) RMON Token Ring Extensions (RFC 1513) |
| Network management
| IEEE 802.5 DTR Concentrator MIB
IEEE 802.5 DTR MAC MIB Catalyst 3900 Enterprise MIB Cisco VLAN Trunking Protocol MIB Cisco Discovery Protocol MIB |
| Dimensions (H x W x D) | 3.4 in. x 17.4 in. x 15.3 in. (8.6 cm x 44.2 cm x 38.7 cm) |
| Memory | 8-MB DRAM |
| Processor | Intel i960SA |
| Weight | 16-18 lb (6-6.7 kg), depending on configuration |
| Description | Specification |
|---|---|
| Operating temperature | 50° to 104°F (10° to 40°C) |
| Operating relative humidity | 8 to 80% |
| Electrical power | 90 to 264 VAC autosensing (single supply) |
| Frequency | 47 to 63 Hz |
| AC current rating | 1.5A @ 115V; 0.75A @ 230V |
| Thermal dispensation | 150W maximum; 512 Btus/hr |
| Storage altitude | 40,000 ft |
The Catalyst 3900 provides the following features:
Configurations larger than 20 Token Ring LAN segments can be constructed by:
To aid in network management, the Catalyst 3900 also maintains status information and a variety of statistics. Status information is available for each port and for each TokenChannel, if defined. Statistics are kept by port, by VLAN, and for the switch as a whole.
The Catalyst 3900 also contains an SNMP MIB-II-compliant management agent that allows a customer-supplied SNMP-based network management system (such as CiscoView) to remotely monitor and control the Catalyst 3900.
In addition, the Catalyst 3900 provides Switched Port Analyzer (SPAN) support, which allows you to monitor traffic on any of the Token Ring ports using a customer-supplied monitoring device such as the Network General Sniffer.
If you need to upgrade the Catalyst 3900 software, you can upgrade through the same serial port used for configuration. The code can be downloaded from a customer-supplied programmable workstation using the Xmodem protocol. Code upgrades can also be accomplished using Trivial File Transfer Protocol (TFTP).
The Catalyst 3900 has a rear stack port that supports an optional Stack Port module, which provides a 140-Mbps, full-duplex link between back-to-back switches, or between the Catalyst 3900 and the Catalyst Matrix switch for configuration requiring up to eight units in a stack.
Other expansion modules include a 4-port fiber Token Ring module, a 4-port copper Token Ring module, a 2-port copper ISL uplink, a 2-port fiber ISL uplink, and an ATM OC-3C uplink.
The Catalyst 3900 ships with a power supply, power cable, and documentation. Table 8-12 lists the product numbers you can use to order the Catalyst 3900 and its expansion module. If a product number ends with an equal sign (=), the item can be ordered only as a spare. If a product number does not end with an equal sign, the item can be ordered as a spare or as a configurable part of a system order. If you order the part as a spare, remember to include the equal sign.
| Description | Product Number |
|---|---|
| 20-port Catalyst 3900 Token Ring switch | WS-C3900 |
| Catalyst 3900 Stack Port module | WS-C3900-STACK |
| RMON feature license | WS-C3900-EMS-LIC |
| Catalyst Matrix | WS-C3020 |
| Catalyst Matrix Redundant Component | WS-X3021 |
| 1-port OC-3c ATM uplink | WS-C3900-ATMSC |
| 2-port 100BaseTX with ISL, UTP, RJ | WS-C3900-2ISL |
| 2-port 100BaseFX with ISL, MMF, SC | WS-C3900-2ISLF |
| 4-port Token Ring fiber module, MMF, ST | WS-C3900-4RF |
| 4-port Token Ring fiber module, UTP/STP, RJ | WS-C3900-4R |
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