Cisco DIN Rail mountable 24V power supply PWR-2955-AC= Hoja De Datos

Cisco Systems, Inc.

All contents are Copyright © 1992–2003 Cisco Systems, Inc. All rights reserved. Important Notices and Privacy Statement.

Page 4 of 19

the queues are processed. The switches support Weighted Round Robin (WRR) scheduling, strict priority queuing or

strict priority scheduling. The WRR scheduling algorithm ensures that lower-priority packets are not entirely starved

for bandwidth and are serviced without compromising the priority settings administered by the network manager.

Strict priority scheduling ensures that higher-priority packets will always get serviced first, ahead of other traffic in

lower-priority queues.

These features allow for prioritization of mission-critical, such as motion-control traffic, critical I/O or sensor data,

video monitoring of security areas over voice (IP telephony traffic), ERP (Oracle, SAP, etc.), and CAD/CAM, which,

in turn, would be scheduled to have precedence over less time-sensitive applications such as FTP or e-mail (SMTP).

For example, it would be highly undesirable to have a large file download destined to one port on a switch and

have quality implications, such as increased latency in industrial control traffic, destined to another port on the

switch. This condition is avoided by ensuring that the control traffic is properly classified and prioritized

throughout the network. Other applications, such as Web browsing, can be treated as low priority and handled on a

best-efforts basis.

Cisco Catalyst 2955 Series switches allocate bandwidth based on several criteria, including MAC source address,

MAC destination address, IP source address, IP destination address, and TCP/UDP port number. Bandwidth

allocation is essential in network environments that require service-level agreements, or when it is necessary for the

network manager to control the bandwidth given to certain users. Cisco Catalyst 2955 Series switches support up to

six policers per Fast Ethernet port and up to 60 policers on a Gigabit Ethernet port. This gives the network

administrator granular control of the network bandwidth.

To provide efficient use of resources for bandwidth-hungry applications like multicasts (common in

producer-consumer data distribution models), Cisco Catalyst 2955 Series intelligent switches support Internet Group

Management Protocol (IGMP) snooping in hardware. Through the support and configuration of IGMP snooping via

Cisco CMS Software, Cisco Catalyst 2955 Series switches deliver outstanding performance and ease of use in

administering and managing multicast applications on the LAN.

The IGMP snooping feature allows the switch to “listen in on” the IGMP conversation between hosts. When a switch

hears an “IGMP join” request from a host for a given multicast group, the switch adds the host’s port number to the

group destination address (GDA) list for that group. When the switch hears an “IGMP leave” request, it removes the

host’s port from the Content Addressable Memory (CAM) table entry.

Per VLAN Spanning Tree Plus (PVST+) allows users to implement redundant uplinks while distributing traffic loads

across multiple links. This is not possible with standard Spanning-Tree Protocol implementations. Cisco UplinkFast

technology ensures immediate transfer to the secondary uplink, a vast improvement over the traditional

30-to-60-second convergence time.

Customers can configure one switch at a time with the embedded Cisco Device Manager, or configure and

troubleshoot multiple switches with Cisco Network Assistant, a standalone network management software

application optimized for LANs of small and medium-sized businesses with up to 250 users. Cisco Device Manager