1
Visit Cisco Connection Online at www.cisco.com
Catalyst 3900 Series — Token Ring Switches
Product Overview
The Cisco Systems Catalyst 3900 Series is a family of second-generation Token Ring switches 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, onedouble-widemodule. 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 3920 comes standard with 24 fixed ports and combines the unsurpassed
performance and functionality of the Catalyst 3900, with an even more cost effective price, making switching to the desktop
a technically superior option to legacy shared-media hub attachments.
Both the Catalyst 3900 and 3920 offer a stack port (optional on the 3900, built-in on the 3920) which allows two units to be
interconnected back-to-back, or up to eight units to be interconnected using the Catalyst 3020 Matrix Switch.
Configuration
The Catalyst 3920 can also be connected to the Cisco 600-wattRedundant AC Power System (RPS); see the “PowerSupplies
and Power Cords” chapter.
For both switches, an application-specific integrated circuit (ASIC) design results in low-latency, wire-speed switching of
unicast, multicast and broadcast frames at either half- or full-duplex speeds, regardless of whether they are source-route
bridged (SRB), source-route transparently bridged (SRT), or source-route switched (SRS). Adaptive cut-through switching
optimizes performance while providing protection from network errors by automatically switching to store-and-forward
when errors reach a user-defined threshold.
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 series switches 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 and Catalyst 3920 automatically learn the ring numbers 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 a Catalyst 3900 series switch to the
network infrastructure.
The Catalyst 3900 series switches provide a wide range of connectivity options for maximum flexibility. Each Token Ring
port supports Dedicated Token Ring (DTR), the IEEE standard that defines direct station attachment at 4, 16, or 32 Mbps.
Furthermore, on the Catalyst 3900 ports 19 and 20 support RI/RO connectivity in addition to DTR. The 4-port fiber module
of the Catalyst 3900 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 adapters 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.
(24 pages)
(68 pages)
(50 pages)
(6 pages)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Commentaires sur ces manuels