ccna certification validity period

ccna certification validity period.Depending on the bandwidth of the switch ports, switches can be divided into two categories: symmetric switching and asymmetric switching. In symmetric switching, switch ports have the same bandwidth; in asymmetric switching, switch ports do not have the same bandwidth. Asymmetric switching enables more bandwidth to be dedicated to the ports connecting to servers or uplink switches to prevent bandwidth bottlenecks from being created.Some common factors that enterprises need to consider when selecting switch equipment include cost, port density, redundant power and POE capabilities, reliability, port speed, frame buffers, and scalability. Also, when choosing a switch type, network designers must choose to use fixed or modular configurations and stacked or non-stacked switches.Fixed configuration switch: no features or options other than the switch's factory configuration are supported; the specific model determines the available features and options.Modular configuration switch: modular configuration switches are more flexible in their configuration and typically have different sized chassis that allow for a different number of modular boards to be installed..92.Cisco Networking Lab CCNA Lab Guide (Release 2) 3Stackable configuration switches: can be interconnected using dedicated cables that provide high bandwidth throughput capability between switches. The following five types of switches exist in enterprise networks. 1Campus LAN switches: Extend network performance in the enterprise LAN and include core, distribution, access, and compact switch platforms that vary. Campus LAN switch platforms include the Cisco 2960, 3560, 3650, 3850, 4500, 6500, and 6800 series.Cloud Managed Switches: Cisco Meraki Cloud Managed Access Switches support virtual stacking of switches, and they monitor and configure thousands of switch ports via the Web without requiring on-site intervention by IT staff. 3 Data center switches: Data center switches improve infrastructure scalability, operational continuity, and transport flexibility. Data center switch platforms include the CiscoNexus family of switches, among others.4 Carrier Switches: Carrier switches are divided into two categories: aggregation switches and Ethernet access switches. Aggregation switches are carrier-grade Ethernet switches that aggregate traffic at the edge of the network. Carrier Ethernet access switches have application layer intelligence, unified services, virtualization, integrated security, and simplified management features.5 Virtual Network Switches: Networks are becoming increasingly virtualized, and the CiscoNexus Virtual Network Switch platform provides secure multi-user services by adding virtualized intelligence to data center networks.