Routers, Switches, Gateways
University of Phoenix
NTC/409 Global Network Architecture and Design
Instructor’s Name: Kimberly Davis
March 23rd, 2015
Switches Gateways and routers are a key hardware infrastructure component. These devices help connect the multiple subnets of a large enterprise network. Understanding the similarities and differences of each device will help a network admin construct a sound and protected network.
There are several types of switches that can be deployed depending upon what the situation requires. The first is a simple L2 switch. This switch operates within layer 2 of OSI model known as the data link layer. The data link layer of the OSI model deals with how data is formatted for transmission and how access to the network is controlled. MAC addresses are also resolved in this layer as well as error checking via CSMADC. Layer 2 switches deal with frames and forwarding them to the end user devices. Switches are commonly used to expand the star topology and branch out from a router to provide connectivity to devices. A layer 3 switch is similar to a layer 2 switch but provides more robust functionality. A layer 3 switch does fast frame forwarding at the hardware level. Layer 3 switches operate in the Networking layer of the OSI model alongside routers. A layer 3 switch can also perform layer 2 switch functionality, but it is not a requirement for the layer 3 switch. Like layer 2 switches a layer 3 switch still requires a router to establish proper routing tables and to connect to a WAN. The layer 3 switch typically uses SNMP for management and routes packets similarly to a router. “IP forwarding typically involves a route lookup, decrementing the Time To Live (TTL) count and recalculating the checksum, and forwarding the frame with the appropriate MAC header to the correct output port” ("Layer 2 Switch And Layer 3 Switch Evolution", 2015).
A router operates solely in the L3 or network...