CCNP ENCOR Certification Cram Notes : Architecture

1.7 Differentiate hardware and software switching mechanisms

1.7.a Process and CEF

Process switching is a software-based switching mechanism that involves forwarding packets through the router's CPU. In this method, each packet is examined and analyzed by the router's processor before forwarding it to the next hop. Process switching is a slow and resource-intensive method that is only used for low-speed links.

Cisco Express Forwarding (CEF) is a hardware-based switching mechanism that involves forwarding packets through the router's specialized ASICs (Application-Specific Integrated Circuits). In this method, each packet is analyzed and forwarded based on the pre-built CEF table. CEF is a faster and more efficient method than process switching, and it is used for high-speed links.

1.7.b MAC address table and TCAM

A MAC address table is a hardware-based table that stores the MAC addresses of devices connected to a switch. When a packet arrives at a switch, the switch checks its MAC address table to determine the port to which the packet should be forwarded. The MAC address table is updated dynamically as devices connect or disconnect from the switch.

Ternary Content Addressable Memory (TCAM) is a specialized hardware component that is used to store and search routing information. TCAM is used for high-speed lookups and can quickly determine the next hop for a packet. It is commonly used in routers and switches to perform forwarding decisions.

1.7.c FIB vs. RIB

The Forwarding Information Base (FIB) and Routing Information Base (RIB) are two components of a router's forwarding plane. The FIB is a hardware-based table that stores the forwarding information for each network, including the next hop and outgoing interface. The FIB is used to perform fast packet forwarding and is updated dynamically as the routing protocol updates the RIB.

The Routing Information Base (RIB) is a software-based table that stores the routing information learned from the routing protocol. The RIB contains the complete routing table and is used to calculate the best path to each destination network. The RIB is used to build the FIB and is updated dynamically as the routing protocol updates the network topology.

In summary, hardware switching mechanisms are faster and more efficient than software-based switching mechanisms. Examples of hardware-based switching mechanisms include CEF, MAC address table, and TCAM. The FIB and RIB are two components of a router's forwarding plane, with the FIB being a hardware-based table that stores forwarding information for each network and the RIB being a software-based table that stores routing information learned from the routing protocol.

2.0 Virtualization

Virtualization technology is the process of creating a virtual version of something, such as hardware, software, storage devices, and network resources. Virtualization technology allows multiple virtual instances of resources to be created and used simultaneously on the same physical infrastructure, enabling greater flexibility, scalability, and cost-effectiveness.

There are several types of virtualization technology, including:

1. Server virtualization: This involves dividing a physical server into multiple virtual machines (VMs) that can run different operating systems and applications independently.

2. Network virtualization: This involves creating virtual networks on top of a physical network infrastructure to provide greater flexibility and agility in managing network resources.

3. Storage virtualization: This involves pooling physical storage resources from multiple devices and presenting them as a single virtual storage device.

4. Desktop virtualization: This involves running multiple desktop operating systems on a single physical device, allowing users to access their desktop environments from anywhere.

Virtualization technology has many benefits, including reducing hardware and maintenance costs, improving resource utilization, increasing flexibility and scalability, and enhancing disaster recovery capabilities. It is widely used in data centers, cloud computing, and other IT infrastructure environments to optimize resource utilization and improve efficiency.