Transcript Chapter 2
Data Centers and IP PBXs LAN Structures Private Clouds IP PBX Architecture IP PBX Hosting Local Area Networks(LANs) at Enterprises • Characteristics – – – – Ownership Limited geography High speeds Shared devices • Ethernet & TCP/IP Facts about LANs • Local in nature • LAN mostly covers a small area • Router ensures you reach outside network • LAN interconnects computers • LANs can be 100 MB or higher • Economical way to share printers • LANs can be wireless • LAN uses file server for network operating system • LANs have switches to connect devices together • LANs segments can be connected by fiber optic cabling • Can access LANs with a password • Wi-Fi routers support multiple protocols • LAN switches reduce cost of cabling devices together • If main file server gets corrupted all LAN devices can be infected • LANs enable students to share applications • LANs can connect to alarm systems • LANs use Ethernet protocols • Wi-Fi eliminates cost of wiring to devices LAN architecture Architecture: how devices fit together in a network. Data Centers Purpose of a data center Environmental considerations Cooling Heating Flooding Secure access Space issues Not too large – space costs $ Not too Small– need to grow Private Clouds • Created within organizations • Emulate cloud providers’ data center structures – Centralized applications – Standardized applications – Self service • Take steps to achieve greater efficiencies • If at provider; dedicate server to single customer; costly Automatic Failover (backup) to a Remote Site Using Replication Software in Virtualized servers Headquarters site Ethernet LAN Remote, backup site WAN** Ethernet LAN Physical host server with virtual machines Servers at headquarters with replication software and virtual machines Physical host servers Switch SAN* Redundant Switches SAN* *Storage area network **Wide Area Network Virtual LANs • virtual local area networks (VLANs) – “Tagged” as a separate LAN in software – Packets in VLANs prioritized for better voice quality and multi-media services – Only certain packets reach them – Shielded from some viruses VoIP Architecture A VoIP Telephone System Remote office Internet Headquarters PSTN Voice over IP system in box Router Wide area network Router Layer 2 switch Gateway Communications Centralized voice mail/unified server communications server PSTN: Public switched Telephone network What do you know about IP PBXs • Changes can be made in software much easier than traditional TDM systems • Phone calls transmitted over the internal IP network • Media gateway has digital signal processor to compress voice • Can connect to PSTN (traditional networks) and Internet (IP) networks • Have built in applications like voice mail • Can transfer voice/video over network • Can contain unified communications email box w/voice mail messages; one software application also video • Can integrate w/some mobile phones • Can easily add more phones/auto attendants/applications • Because it’s digital/ can store more data/ recorded calls • Easier to manage Steps in VoIP PBX Selection • • • How do you determine the organizations’ needs? – Size of org. in number of people – Number of sites; – Requirements for conference calls – may need more phone lines – Employee functions – does each staff need a phone? – Look at employee usage – phone bill $s; # of calls – Call center needs? – customer support – Budget; security needs – infrastructure – Growth? Financial officer, CEO What are the 5 most important criteria for system selection? – Cost, User friendliness; reliability, security; size & energy needs What questions will you ask vendors in order to evaluate them? – What is the difference with competitors; references; service; do they offer more equipment; maintenance? Specifications of what’s included in contract & maintenance contract; what’s included; # of phones, capacity without a processor; cost?; redundancy? Global reach? The Rationale for IP PBXs • VoIP advantages – Open standards • Applications for call centers, voice mail etc. • Telephone compatibilities – Voice and data on interoffice trunks – Centralized Administration – Centralized Unified Communications Hosted IP Telephone Systems - Rationale • Rationale – Lack of in-house expertise – Uncertain growth – Dispersed sites • Media server, gateway and software at provider • Web interface for customer programming Provider with VoIP hardware & software Private or Public Internet VoIP Links Should our Organization Use a Hosted IP PBX? • • • • • • • • • • • Absolutely We don’t want to do maintenance Just one Ethernet network We have a positive vision of technology Easier for vendor not us to update Save $ on staff Upgrades by host More skills at host For small companies, hosted IP has more services Save on energy Not stuck with capital for expensive equipment – more flexible • • • • • • • • • • • Never! Like current system, More $ monthly Others will look down on company image poor Security worries Want to control system Tech. too new If telephone line is cut no service Not supported in enough countries Our intellectual property not secure over Internet What happens if host goes out of business? Summary • LAN architecture – Backbone • • • • Private clouds Structure of VoIP telephone systems Hosted IP telephone systems VLANs (virtual local area networks) & Storage Area Networks