Unit11
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VLANs can be created in three ways: port-based using switch port assignments, layer 2 grouping based on MAC addresses, and layer 3 grouping based on IP addresses. Network Attached Storage uses common protocols like NFS, CIFS, FTP and HTTP to provide file services over a network. Storage Area Networks place storage devices on a separate fibre channel network connected to servers to allow centralized data management and separation of data transfers from the local area network. Fault tolerance uses techniques like redundant components, RAID, clusters and UPS systems to prevent disasters from downtime if failures occur. Small office/home office networks aim to share internet access, files, printers and back up data between a few users. DSL and cable internet can be
Unit11
- 2. Overview • Using Switches to Create VLANs • Network Attached Storage • Storage Area Networks • Disaster Recovery • Fault Tolerance • Working with a Small Network—The SOHO • Security Impact on the Network
- 3. Using Switches to Create VLANs • A local area network (LAN) is often considered a broadcast domain • Broadcast domains are bounded by any device that translates above the physical layer • VLANs are created using switches
- 4. VLANs
- 5. VLANs • You can create a VLAN in three ways – Port-based. • Early on, VLANs were constructed through the simple assignment of ports on a switch to a VLAN identified by a number.. – Layer 2 grouping. • The layer 2 grouping method is also called the MAC Membership VLAN. As you might guess, it’s based on the MAC address of the computer – Layer 3 grouping. • This method uses the network layer address to identify the computers that should participate in a particular VLAN. If TCP/IP is in use, this would be the IP address; if IPX/SPX is in use, it would be the IPX address..
- 6. Network Attached Storage • A NAS device is dedicated to nothing more than serving the network with storage • A NAS device is a server of sorts because it provides file services • A workstation in a network using NAS does not authenticate to the NAS device
- 8. NAS • NAS communicates using common protocols, including : – Network File System (NFS) typically found in UNIX environments – Common Internet File System (CIFS) in Windows networks – File Transfer Protocol (FTP) and Hypertext Transfer Protocol (HTTP) in IP networks
- 9. Storage Area Networks • A SAN is a network of one or more storage devices that communicate outside the regular network with one or more servers • In the SAN, storage devices are placed on a separate network using fibre channel technology to connect to a hub • Servers are also equipped with special adapters to connect to the hub and access the stored data on any of the connected storage devices • SANs make it possible to separate large transfers of data from the LAN • Central management of data is possible via a SAN, yet the data is still available to many different systems and applications
- 10. SAN
- 11. Disaster Recovery • Types of disasters you might encounter : – Mission-critical server failures. • Any component within a server can cause it to fail to provide services, including hard disk, power supply, processor, memory, and even the network interface. – Network component failures. • When network components such as hubs, switches, and routers fail, entire sections of the network become unusable. – Building problems. • If the building power goes out, the wiring is damaged, or the wide area network (WAN) link is cut, the network fails. – Mother Nature. • Floods, tornadoes, fires, and the occasional monsoon are the types of disasters that can completely devastate the entire network and all the data stored within it.
- 12. Disaster Recovery • In the event of a total disaster, these are your options : – Wait to resume operations after a new site can be constructed. – Temporarily move operations to another site in a different location. – Use a “cold” site, which is another location with equipment available to begin operations as soon as you can move personnel to that location and restore data to that equipment. – Use a “hot” site, which is another location that mirrors your location’s data operations, usually is directly connected to your network, and is able to begin operations the moment your location is affected by the disaster.
- 13. Fault Tolerance • Fault tolerance is another term for redundancy • less expensive to prevent a disaster than to restore one • Fault tolerance can work for the following : – Memory. • Some servers support error-correcting memory with a spare memory module to use in case of memory failure. – Network interface cards (NICs). • NICs can be redundant in two ways. They can share the network traffic, or one of the NICs can wait until the first fails before it kicks in.
- 14. Fault Tolerance – Redundant Array of Inexpensive Disks (RAID). • Data is mirrored, shared, or striped across multiple disks. Pay attention to these versions of RAID: • RAID 1: Mirroring disks connected to a single hard disk controller, or duplexing disks connected to two different hard disk controllers. • RAID 5: A group of three or more disks is combined into a volume with the disk striped across the disks, and parity is used to ensure that if any one of the disks fails, the remaining disks will still have all data available. – Power supplies. • One power supply takes over if the original fails. – Clusters. • Two or more servers are grouped to provide services as if the group were a single server. A cluster is transparent to end users. Usually, a server member of a cluster can take over for a failed partner with no impact on the network.
- 15. Working with a Small Network The SOHO • The goals of a SOHO network are different from those of an enterprise network. Most, listed below, are fairly basic: – Share an Internet connection. – Share printers and scanners. – Share files, access e-mail messages, and back up the data. – Access a corporate network via virtual private network (VPN). – Send or receive faxes without a fax machine.
- 16. Using DSL to Access the Internet • DSL uses standard telephone wires to carry high-speed data • doesn’t interrupt standard telephone calls • ADSL is ideal for SOHO networks
- 17. A DSL connection can be shared.
- 18. Using Cable Modems for Internet Sharing • The Data Over Cable Service Interface Specification (DOCSIS) is the cable TV industry’s response to the telephone companies’ domination over Internet connectivity • Cable TV companies have since upgraded their backend networks with hybrid fiber coax (HFC) to bring fiber optics into the cable TV network, which does the trick • In DOCSIS 1, a download bandwidth of 40 Mbps is available, with a 10-Mbps upload speed • The media is shared by all the cable subscribers within a local area • A cable modem is shared in the same way that a DSL connection can be shared
- 19. Home Satellite • Direct broadcast satellite TV is another medium under exploration for delivering high-speed Internet services • The other type of home satellite is a point-to-point wireless service using line of sight connections between the Internet Service Provider (ISP) and the subscriber
- 20. Using Dialup • Dialup connections are the mainstay for many a SOHO • SOHO will access the Internet only through individual dialup connections on each of the network’s PCs • However, it is possible to share a dialup connection