Коммутаторы Cisco Catalyst серии 2955

Коммутаторы семейства Cisco Catalyst 2950 – это коммутаторы фиксированной конфигурации, которые предназначены для инфраструктуры сетей Fast Ethernet и Gigabit Ethernet и обеспечивают производительность на скорости среды передачи. Коммутаторы поставляются с двумя типами программного обеспечения и в самых различных конфигурациях, благодаря чему можно подобрать подходящий вариант для любого предприятия малого и среднего бизнеса, а также удаленных офисов и производственных сред. Стандартная программная конфигурация предлагает базовые функции программного обеспечения Cisco IOS для передачи данных, голоса и видео. Для интеллектуальных сетей, которым требуются дополнительные функции безопасности, расширенные функции управления качеством обслуживания (QoS) и высокий уровень доступности на границе сети, предназначены модели с улучшенным программным обеспечением (EI), включающие поддержку таких функций, как ограничение скорости и фильтрация трафика.

Для применения в производственных условиях и на траснпорте отлично подходит новый коммутатор серии Cisco Catalyst 2955. Кроме того, он может найти применение в коммунальных предприятиях и других задачах, где условия эксплуатации не позволяют применять обычные коммутаторы.

Бесплатно распространяемое программное приложение Cisco Network Assistant для централизованного управления коммутаторами семейства Catalyst 2950 упрощает администрирование коммутаторов, маршрутизаторов и беспроводных точек доступа Cisco, предлагая дружественный к пользователю графический интерфейс для удобства конфигурирования, поиска и устранения неисправностей, а также включения и мониторинга элементов сети.

Cisco Catalyst 2955 Series Switches

Product Overview

Cisco Catalyst^® 2955 Series switches are industrial-grade switching products that provide wire-speed Fast Ethernet and Gigabit Ethernet connectivity for deployment in harsh environments. The Cisco Catalyst 2955 Series operates in environments such as industrial networking solutions (industrial Ethernet deployments), intelligent transportation systems (ITS), and transportation network solutions. It integrates into military equipment, Supervisory Control and Data Acquisition (SCADA) systems, power generation systems, waste water treatment facilities, building automation systems, warehouses, and any other facilities or applications where the environmental conditions or suspended solid concentrations exceed the specifications of other commercial switching products. The Cisco Catalyst 2955 Series uses industrial-grade components, a compact form factor, convection cooling, and relay output signaling to extend intelligent services such as enhanced security, high availability, and advanced quality of service (QoS) to areas that cannot be served by traditional commercial-grade Ethernet switches.

Embedded in all Cisco Catalyst 2955 Series switches is the Cisco Device Manager software, which allows users to easily configure and monitor the switch using a standard Web browser, eliminating the need for more complex terminal emulation programs and knowledge of the command-line interface (CLI). Customers can easily initialize the switch with web-based Cisco Express Setup, without using the CLI. In addition, with Cisco Network Assistant, a standalone network management software, customers can simultaneously configure and troubleshoot multiple Cisco Catalyst desktop switches. Cisco Device Manager, Cisco Express Setup, and Cisco Network Assistant reduce the cost of deployment by enabling less-skilled personnel to set up switches quickly. Furthermore, Cisco Catalyst 2955 Series switches provide extensive management tools using Simple Network Management Protocol (SNMP) network management platforms such as CiscoWorks.

This product line offers Cisco IOS^® Software functionality for traditional data, video, and voice services, with enhanced intelligent services features for additional security, advanced QoS, and high availability. Intelligent services are critical in supporting the reliability and determinism of proprietary Layer 2 solutions typical of industrial Ethernet deployments, while providing the advantages (standardization, open connectivity, bandwidth, integration, etc.) of an advanced Ethernet switching architecture. These intelligent services include Layers 2-4 traffic prioritization, rate limiting, and security filtering, helping to ensure the high uptime, low latency, deterministic performance, and data integrity critical for industrial automation control networks.

Cisco Catalyst 2955 Series switches consist of the following devices:

• Cisco Catalyst 2955T-12 - Twelve 10/100 ports and two fixed 10/100/1000BASE-T uplink ports
• Cisco Catalyst 2955C-12 - Twelve 10/100 ports and two fixed 100BASE-FX multimode uplink ports
• Cisco Catalyst 2955S-12 - Twelve 10/100 ports and two fixed 100BASE-LX single-mode uplink ports

Intelligence in the New Ethernet Networks

Currently, non-Ethernet Layer 2 networks are evolving from traditional fieldbuses or proprietary technologies to standards-based Ethernet networks. The progression to Ethernet is driven by a multitude of factors, including:

• Standardization - There are hundreds of millions of Ethernet devices around the world; Ethernet has become the prevalent Layer 2 technology based on widely adopted standards.
• IP Connectivity - Ethernet is the most ubiquitous Layer 2 technology for Internet connectivity, in turn providing unprecedented communications potential to networks that have been traditionally isolated.
• Bandwidth - Orders of magnitude above other existing technologies, Ethernet takes advantage of the increased computational power of the new network hosts (I/O devices, motion machinery, sensors, intelligent electronic devices, etc.) being deployed today. This allows for real-time control and data gathering for a multitude of applications that were not previously feasible, including preventive maintenance, total quality control monitoring, remote monitoring, and asset management and optimization.
• Multiple services on a single infrastructure - Intelligent Ethernet allows a single network to carry multiple vendor implementations of control [EtherNet/IP, Modbus TCP, Foundation Fieldbus High Speed Ethernet (HSE) and various Advanced Traffic Management Systems (ATMS)], and to use the same investment to also deliver traditional voice (telephony), data (e-mail, technical support, and browsing), and video services (video monitoring).
• Multilayer integration - All of the elements described above allow for the integration of higher-level applications such as enterprise resource planning (ERP), manufacturing execution systems (MES), and advanced traffic management systems to the floor control layer (programmable logic controllers [PLCs], PC-based control systems, traffic control equipment, and human-machine interfaces [HMIs]). This allows for a true flow of data and automation from the demand side (customer placing and order) to the factory floor (assembly line) or from the monitoring devices in a freeway all the way to the emergency response systems, as well as real-time control in SCADA applications. As organizations increasingly rely on Ethernet networks, it is important to ensure high availability, security, scalability, and control. By adding Cisco IOS Software functionality to new network applications, users can now deploy network-wide intelligent services that address these requirements in a consistent way - from the I/O or monitoring device to the core and through the WAN.

Network Security through Advanced Security Features

Cisco Catalyst 2955 Series switches offer enhanced data security through numerous security features. These features allow customers to enhance network security with capabilities to secure traffic through the protection of passwords and configuration information; to provide options for network security based on users, ports, and Media Access Control (MAC) addresses; and to enable more immediate reactions to intruder and hacker detection.

Secure Shell (SSH) Protocol and SNMPv3 protect information from tampering or eavesdropping by encrypting information being passed along the network, thereby guarding administrative information. Private VLAN Edge isolates ports on a switch, ensuring that traffic travels directly from the entry point to the aggregation device through a virtual path and cannot be directed to another port.

Port-based access control parameters (ACPs) restrict sensitive portions of the network by denying packets based on source and destination MAC addresses, IP addresses, or Transmission Control Protocol/User Datagram Protocol (TCP/UDP) ports. ACP lookups are done in hardware, so forwarding performance is not compromised when implementing this type of security in the network. In addition, time-based ACPs allow configuration of differentiated services based on time periods. ACPs can also be applied to filter traffic based on differentiated services code point (DSCP) values. Port security provides another means to ensure that appropriate users are on the network, by limiting access based on MAC addresses.

For authentication of users with a Terminal Access Controller Access Control System (TACACS+) or RADIUS server, 802.1x provides port-level security. 802.1x in conjunction with a RADIUS server allows for dynamic port-based user authentication. 802.1x-based user authentication can be extended to dynamically assign a virtual LAN (VLAN) based on a specific user, regardless of where that user connects on the network. This intelligent adaptability provides greater flexibility and mobility to the network's stratified user populations. By combining access control and user profiles with secure network connectivity, services, and applications, customers can more effectively manage user mobility and drastically reduce the overhead associated with granting and managing access to network resources.

With multilayer Cisco Catalyst 2955 Series switches, network managers can implement high levels of console security. Multilevel access security on the switch console and a Web-based management interface prevent unauthorized users from accessing or altering switch configurations. TACACS+ or RADIUS authentication enable centralized access control of the switch and restrict unauthorized users from altering the configuration. Deploying security can be done through Cisco CMS Software Security Wizards, which ease the deployment of security features that restrict user access to a server, a portion of the network, or the entire network.

Network Control through Advanced QoS and Rate Limiting

Cisco Catalyst 2955 Series switches offer superior and highly granular QoS based on Layers 2-4 information, to help ensure that network traffic is classified and prioritized, and that congestion is avoided in the best possible manner. These switches can classify, reclassify, police (determine if the packet is in or out of predetermined profiles and affect actions on the packet), and mark or drop the incoming packets before the packet is placed in the shared buffer. Packet classification allows the network elements to discriminate between various traffic flows and to enforce rate-limiting policies based on Layer 2 and Layer 3 QoS fields.

To implement QoS, these switches first identify traffic flows or packet groups. They classify or reclassify these groups using the DSCP field in the IP packet and/or the 802.1p class of service (CoS) field in the Ethernet packet. Classification and reclassification can also be based on criteria as specific as the source or destination IP address, source or destination MAC address, or the Layer 4 TCP/UDP ports. At the ingress (incoming port) level, Cisco Catalyst 2955 Series switches can also perform policing and marking of the packet.

After the packet goes through classification, policing, and marking, it is assigned to the appropriate queue before exiting the switch. Cisco Catalyst 2955 Series switches support four egress (outgoing port) queues per port, allowing the network administrator to be more discriminating and specific in assigning priorities for the various applications on the network. At the egress level, the switch performs scheduling - an algorithm that determines the order in which 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.

Network Availability

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.

Network Management

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 offers a simple and intuitive GUI interface for configuring and monitoring the switch. The software is Web-based and embedded in Cisco Catalyst 3750, 3650, 3550, 2970, 2960, 2950, 2955, and 2940 Switches. Cisco Device Manager reduces the cost of deployment by enabling less-skilled personnel to quickly and simply set up switches.

Cisco Network Assistant Software provides an integrated management interface for delivering intelligent services, such as multilayer switching, QoS, multicast, and security ACLs. Cisco Network Assistant Software allows administrators to take advantage of benefits formerly reserved for only the most advanced networks without having to learn the CLI, or even the details of the technology. With Cisco Network Assistant, customers can configure multiple ports and switches simultaneously, perform software updates across multiple switches at once, and copy configurations to other switches for rapid network deployments. Bandwidth graphs and link reports provide useful diagnostic information, and the topology map gives network administrators a quick view of the network status. Cisco Network Assistant supports a wide range of Cisco Catalyst intelligent switches from Cisco Catalyst 2940 through Cisco Catalyst 4506. Through a user-friendly GUI, users can configure and manage a wide array of switch functions and start the device manager of Cisco routers and Cisco wireless access points.

The Cisco Network Assistant Software Guide Mode leads the user step-by-step through the configuration of advanced features and provides enhanced online help for context-sensitive assistance. Cisco AVVID (Architecture for Voice, Video and Integrated Data) Wizards provide automated configuration of the switch to optimally support video streaming or video conferencing, voice over IP (VoIP), and mission-critical applications. In addition, Smartports offers a set of verified feature macros per connection type in an easy-to-apply manner. With these macros, users can consistently and reliably configure essential security, availability, quality of service, and manageability features recommended for Cisco Business Ready Campus solutions with minimal effort and expertise. These Wizards and Smartports can save hours of time for network administrators, eliminate human errors, and ensure that the configuration of the switch is optimized for these applications.

In addition to Cisco Network Assistant Software, Cisco Catalyst 2955 Series switches provide extensive management tools using Simple Network Management Protocol (SNMP) network management platforms such as CiscoWorks. Managed with CiscoWorks, Cisco Catalyst switches can be configured and managed to deliver end-to-end device, VLAN, traffic, and policy management. Coupled with CiscoWorks, Cisco Resource Manager Essentials, a Web-based management tool, offers automated inventory collection, software deployment, easy tracking of network changes, views into device availability, and quick isolation of error conditions.

Enhanced Hardware Features

The Cisco Catalyst 2955 Switch has been designed for deployment in harsh environments. Through the use of special thermal design techniques and industrial-rated components, the Cisco Catalyst 2955 is rated to operate at extreme temperatures (-40° to 60°C; -40° to 140°F). Robust mechanical specifications allow for its deployment as a mobile platform and under extreme vibration and shock environments (50G trapezoidal shock pulse). The compact form factor, DIN rail mounting, and dual cabling orientations facilitate its deployment into industrial enclosures, traffic control cabinets, and transportation vehicles. Two normally open relays can be associated with the different port alarms, power alarms, and high temperature conditions to send an output signal to other external mechanisms (visible or audible alarms, for example), HMIs, or PLCs for a controlled shutdown. Dual power inputs provide for optional redundant power supplies, guaranteeing an even higher level of resiliency and reliability.

Figure 1

Cisco Catalyst 2955 Series Switches

Table 1 Product Features and Benefits

Table 2 Product Specifications