May, 2006
802.x
Written by The Geekette on May 29, 2006 – 6:56 pmPosted in Networking | No Comments »
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Loading ...| 802 | Overview | Basics of physical and logical networking concepts. |
| 802.1 | Bridging | LAN/MAN bridging and management. Covers management and the lower sub-layers of OSI Layer 2, including MAC-based bridging (Media Access Control), virtual LANs and port-based access control. |
| 802.2 | Logical Link | Commonly referred to as the LLC or Logical Link Control specification. The LLC is the top sub-layer in the data-link layer, OSI Layer 2. Interfaces with the network Layer 3. |
| 802.3 | Ethernet | "Grandaddy" of the 802 specifications. Provides asynchronous networking using "carrier sense, multiple access with collision detect" (CSMA/CD) over coax, twisted-pair copper, and fiber media. Current speeds range from 10 Mbps to 10 Gbps. |
| 802.4 | Token Bus | Disbanded |
| 802.5 | Token Ring | The original token-passing standard for twisted-pair, shielded copper cables. Supports copper and fiber cabling from 4 Mbps to 100 Mbps. Often called "IBM Token-Ring." |
RAID
Written by The Geekette on May 22, 2006 – 2:28 amPosted in Hardware | No Comments »
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| Level | Characteristics |
| 0 | Stripe Sets w/o parity - can use diff types of drives - 2 or more drives - best performance but no fault-tolerance |
| *1 | Mirroring & Duplexing - 2 sep drives - Best performance and the best fault-tolerance in a multi-user system. |
| 2 | This type uses striping across disks with some disks storing error checking and correcting (ECC) information. It has no advantage over RAID-3. |
| 3 | Parity written to one disk. best for single-user systems with long record applications. |
| *4 | Independent disks with shared parity - high transaction rate and low ratio of ECC (parity) disks to data disks - writes parity across one disk - high efficiency - bad write transaction rate - 3 drive min - one disk parity disk |
| *5 | Striping with parity - 3 drives needed - Read Only efficient - writes parity across multiple disks - greater speed and redundancy |
SCSI
Written by The Geekette on May 22, 2006 – 2:15 amPosted in Hardware, Networking | No Comments »
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Type |
Bus Size Bits |
# Devices | Cable Length m/ft |
Bus Speed MHZ |
Max Transfer Speeds MBs/sec |
Pins |
| SCSI (SCSI 1) | 8 | 8 | 6m / 20ft | 5 | 5 | 50 |
| Wide SCSI (SCSI 2) | 16 | 16 | 6m / 20ft | 5 | 10 | 50 |
| Fast SCSI (SCSI 1) | 8 | 8 | 3m / 10ft | 10 | 10 | 50 |
| Wide Fast SCSI (SCSI 2) | 16 | 16 | 3m / 10ft | 10 | 20 | 50 |
| Ultra SCSI | 8 | 8 | 1.5m / 5ft | 20 | 20 | 50 |
| Ultra Wide SCSI (SCSI 3) | 16 | 8 | 1.5m / 5ft | 20 | 40 | 68 |
| Ultra Fast | 16 | 16 | 1.5m / 5ft | 40 | ||
| Ultra 2 SCSI | 8 | 8 | 12m / 40ft | 40 | 40 | 68 |
| Wide Ultra 2 SCSI | 16 | 16 | 12m / 40ft | 40 | 80 | 68 |
| Ultra160 SCSI | 16 | 16 | 12m / 40ft | 40 | 160 | 68 |
DSL Wired Up
Written by The Geekette on May 4, 2006 – 3:18 pmPosted in Technology | No Comments »
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DSL is a service that connects us to the internet with a high-speed connection over your phone line. When you order it, in a way it can be thought of as adding a feature to your phone line - like call waiting or caller ID. But a lot more goes into adding DSL to a phone line than just "turning on" the service.
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