a administrative overhead of IP allocations - because of flat subnet 2 Virtualization and Cloud Computing Table 2.3 Layer 3 VPNs: advantages and disadvantages. Advantages Extremely scalable for fast deployment Readiness for voice and data convergence "Any to any" connectivity - a shorter hop count between two local sites Enterprises leverage the service provider's technical expertise for routing Disadvantages Increased costs - due to requiring customer router hardware Class of service and quality of service usually incur additional fees IP addressing modifications would have to be submitted to the service provider Table 2.4 Router versus switch. Router Switch Definition Connects two or more Connects many devices networks together and together on a network; forwards packets between more advanced than a hub OSI layer Network layer (L3) devices Data link or network layer (L2 or L3) Data form Packet Frame and packet Address used for IP address MAC address data transmission Table Stores IP addresses in A network switch stores routing table MAC addresses in a lookup table Transmission type At initial level broadcast; First broadcast; then then unicast and multicast unicast and multicast Function Directs data in a network. Allow to connect multiple Passes data between home device and port can be computers, and between managed; VLAN can computers and the modem create security also can apply Speed 1-10 Mbps (wireless) 10/100 Mbps, 1 Gbps 100 Mbps (wired) 2.3 Network Virtualization examples of these networks. While properly segmenting multiple network instances, such technologies commonly support sharing of physical resources among them. The term virtual sharing networks (VSNs) has recently been suggested for these types of networks [23]. Originally defined as a network of computers located within the same area, today LANs are identified by a single broadcast domain in which the information broadcasted by a user is received by every other user on that LAN while it is prevented from leaving the LAN using a router. The forma