Cisco Certified Field Technician (CCT) 800-150 Cisco Study Notes

The Data Link Layer (Layer 2) of the OSI model is responsible for node-to-node data transfer and plays a crucial role in error detection and media access control. It ensures that data frames are transmitted to the correct device on a local network segment.​

This layer is divided into two sublayers:​

Logical Link Control (LLC):Manages frame synchronization, flow control, and error checking.

Media Access Control (MAC):Controls how devices on the network gain access to the medium and permission to transmit data.

Together, these sublayers ensure reliable data transmission by detecting and possibly correcting errors that may occur in the Physical Layer. They also manage how devices share the transmission medium, preventing collisions and ensuring orderly communication.​

When installing a fan module in a Cisco Nexus fixed-configuration switch, it's crucial to ensure that theairflowdirection of the new fan matches the existing airflow configuration. Mismatched airflow directions can lead to inefficient cooling or even overheating of components, potentially affecting the performance or lifespan of the switch.

Cisco offers fan modules infront-to-backorback-to-frontairflow variants, and consistency is required for proper thermal management. These modules are also typically hot-swappable, meaning powering down the switch is not necessary.

TheUCS Fabric Interconnectis the central management and communication hub of theCisco UCS (Unified Computing System)environment. It integrates compute, network, and storage access into a unified system.

Fabric Interconnects:

Manage all servers and I/O modules connected to the UCS domain

Provide connectivity and are the point of integration with the Cisco UCSManager

Offer high-availability and centralized policy management

Other options like the Nexus or MDS switches do not serve this unified management function in a UCS deployment.

In enterprise networking, remote sites or branch offices connect to the central campus network using:​

WAN Links:These are dedicated communication paths that connect geographically dispersed networks. WAN links can be leased lines, MPLS circuits, or other forms of long-distance connectivity that facilitate reliable data transmission between remote sites and the main campus.​

IPsec VPN Tunnels:Internet Protocol Security (IPsec) VPNs provide secure, encrypted tunnels over the public internet, allowing remote sites to connect to the enterprise network securely. This method is cost-effective and widely used for connecting branch offices to the central network infrastructure.​

Access layer switches (Option A) and LAN core switches (Option E) are components within a local network and do not facilitate remote connectivity. Ad hoc Wi-Fi networks (Option D) are temporary and lack the security and reliability required for enterprise-level remote connections.​